Part 4

(1) The scope of this Part shall be as described in Subsection 1.1.2. of Division A.

(1) Buildings and their structural members and connections including formwork and falsework shall be designed to have sufficient structural capacity and structural integrity to safely and effectively all loads, effects of loads and influences that may reasonably be expected, having regard to the expected service life of buildings, and shall in any case satisfy the requirements of this Section.

(2) Buildings and their structural members shall be designed for serviceability, in accordance with Articles 4.1.3.4. to 4.1.3.6.

(3) All permanent and temporary structural members, including formwork and falsework of a building, shall be protected against loads exceeding the specified loads during the construction period except when, as verified by analysis or test, temporary overloading of a structural member would result in no impairment of that member or any other member.

(4) Precautions shall be taken during all stages of construction to ensure that the building is not damaged or distorted due to loads applied during construction.

(1) Except as provided in Sentence (2) and (3), buildings and their structural members shall be designed in conformance with the procedures and practices provided in this Part.

(2) Provided the design is carried out by a person especially qualified in the specific methods applied and provided the design demonstrates a level of safety and performance in accordance with the requirements of this Part, buildings and their structural components falling within the scope of this Part that are not amenable to analysis using a generally established theory may be designed by,

(a) evaluation of a full-scale structure or a prototype by a loading test, or

(b) studies of model analogues.

(3) Communications towers, dish antennas and their supporting structures shall conform to CSA S37, “Antennas, Towers, and Antenna Supporting Structures”.

(1) Except as provided in Article 4.1.2.2., the categories of loads, specified loads and effects set out in Table 4.1.2.1.A. shall be taken into consideration in the design of a building and its structural members and connections.

(2) Minimum specified values of the loads described in Sentence (1), as set forth in Subsections 4.1.4. to 4.1.8., shall be increased to account for dynamic effects where applicable.

(3) For the purpose of determining specified loads S, W or E in Subsections 4.1.6. to 4.1.8., buildings shall be assigned an Importance Category based on intended use and occupancy, in accordance with Table 4.1.2.1.B.

(1) Where a building or structural member can be expected to be subjected to loads, forces or other effects not listed in Article 4.1.2.1., such effects shall be taken into account in the design based on the most appropriate information available.

(1) In this Part, the term,

(a) “limit states” means those conditions of a building structure that result in the building ceasing to fulfill the function for which it was designed (Those limit states concerning safety are called ultimate limit states and include exceeding the load-carrying capacity, overturning, sliding and fracture; those limit states that restrict the intended use and occupancy of the building are called serviceability limit states and include deflection, vibration, permanent deformation and local structural damage such as cracking; and those limit states that represent failure under repeated loading are called fatigue limit states),

(b) “specified loads (D, E, H, L, P, S, T and W)” mean those loads set out in Table 4.1.2.1.A.,

(c) “principal load” means the specified variable load or rare load that dominates in a given load combination,

(d) “companion load” means a specified variable load that accompanies the principal load in a given load combination,

(e) “service load” means a specified load used for the evaluation of a serviceability limit state,

(f) “principal-load factor” means a factor applied to the principal load in a load combination to account for the variability of the load and load pattern and the analysis of its effects,

(g) “companion-load factor” means a factor that, when applied to a companion load in the load combination, gives the probable magnitude of a companion load acting simultaneously with the factored principal load,

(h) “importance factor, I,” means a factor applied in Subsections 4.1.6. to 4.1.8. to obtain the specified load and take into account the consequences of failure as related to the limit state and the use and occupancy of the building,

(i) “factored load” means the product of a specified load and its principal-load factor or companion-load factor,

(j) “effects” refers to forces, moments, deformations or vibrations that occur in the structure,

(k) “nominal resistance, R,” of a member, connection or structure, is based on the geometry and on the specified properties of the structural materials,

(l) “resistance factor, Φ,” means a factor applied to a specified material property or to the resistance of a member, connection or structure, and that, for the limit state under consideration, takes into account the variability of dimensions and material properties, workmanship, type of failure and uncertainty in the prediction of resistance, and

(m) “factored resistance, ΦR,” means the product of nominal resistance and the applicable resistance factor.

(1) A building and its structural components shall be designed to have sufficient strength and stability so that the factored resistance, ΦR, is greater than or equal to the effect of factored loads, which shall be determined in accordance with Sentence (2).

(2) The effect of factored loads for a building or structural component shall be determined in accordance with the load combination cases listed in Table 4.1.3.2. and the requirements of this Article, the applicable combination being that which results in the most critical effect.

(3) Where the effects due to lateral earth pressure, H, restraint effects from pre-stress, P, and imposed deformation, T, affect the structural safety, they shall be taken into account in the calculations, with load factors of 1.5, 1.0 and 1.25 assigned to H, P and T respectively.

(4) Except as provided in Sentence 4.1.8.16.(1), the counteracting factored dead load, 0.9D in load combination cases 2, 3 and 4 and 1.0D in load combination case 5, shall be used when the dead load acts to resist overturning, uplift, sliding, failure due to stress reversal, and to determine anchorage requirements and the factored resistance of members.

(5) The principal-load factor 1.5 for live load, L, in Table 4.1.3.2. may be reduced to 1.25 for liquids in tanks.

(6) The companion-load factor 0.5 for live load, L, in Table 4.1.3.2. shall be increased to 1.0 for storage areas and for equipment areas and service rooms referred to in Table 4.1.5.3.v1

(7) The load factor 1.25 for dead load, D, in Table 4.1.3.2. for soil, superimposed earth, plants and trees shall be increased to 1.5, except that when the soil depth exceeds 1.2 m, the factor may be reduced to 1 + 0.6/h_s but not less than 1.25, where h_s is the depth of soil in metres supported by the structure.

(8) Earthquake load, E, in load combination case 5 of Table 4.1.3.2. includes horizontal earth pressure due to earthquake determined in accordance with Sentence 4.1.8.16.(4).

(9) Provision shall be made to ensure adequate stability of the structure as a whole and adequate lateral, torsional and local stability of all structural parts.

(10) Sway effects produced by vertical loads acting on the structure in its displaced configuration shall be taken into account in the design of buildings and their structural members.

(1) A building and its structural components, including connections, shall be checked for fatigue failure under the effect of the cyclical loads, as required in the standards listed in Section 4.3.

(2) Where vibration effects, such as resonance and fatigue resulting from machinery and equipment, are likely to be significant, a dynamic analysis shall be carried out.

(1) A building and its structural components shall be checked for serviceability limit states as defined in Clause 4.1.3.1.(1)(a)v1 under the effect of service loads for serviceability criteria specified or recommended in Articles 4.1.3.5. and 4.1.3.6. and in the standards listed in Section 4.3.

(1) In proportioning structural members to limit serviceability problems resulting from deflections, consideration shall be given to,

(a) the intended use of the building or member,

(b) limiting damage to non-structural members made of materials whose physical properties are known at the time of design,

(c) limiting damage to the structure itself, and

(d) creep, shrinkage, temperature changes and prestress.

(2) The lateral deflection of buildings due to service wind and gravity loads shall be checked to ensure that structural elements and non-structural elements, whose nature is known at the time the structural design is carried out, will not be damaged.

(3) Except as provided in Sentence (4), the total drift per storey under service wind and gravity loads shall not exceed 1/500 of the storey height unless other drift limits are specified in the design standards referenced in Section 4.3.

(4) The deflection limits required in Sentence (3) do not apply to industrial buildings or sheds if experience has proven that greater movement will have no significant adverse effects on the strength and function of the building.

(5) The building structure shall be designed for lateral deflection due to E, in accordance with Article 4.1.8.13.

(1) Floor systems susceptible to vibration shall be designed so that vibrations will have no significant adverse effects on the intended occupancy of the building.

(2) Where the fundamental vibration frequency of a structural system supporting an assembly occupancy used for rhythmic activities, such as dancing, concerts, jumping exercises or gymnastics, is less than 6 Hz, the effects of resonance shall be investigated by means of a dynamic analysis.

(3) A building susceptible to lateral vibration under wind load shall be designed in accordance with Article 4.1.7.2. so that the vibrations will have no significant adverse effects on the intended use and occupancy of the building.

(1) The specified dead load for a structural member consists of,

(a) the weight of the member itself,

(b) the weight of all materials of construction incorporated into the building to be supported permanently by the member,

(c) the weight of partitions,

(d) the weight of permanent equipment, and

(e) the vertical load due to earth, plants and trees

(2) Except as provided in Sentence (5), in areas of a building where partitions other than permanent partitions are shown on the drawings, or where partitions might be added in the future, allowance shall be made for the weight of such partitions.

(3) The partition weight allowance in Sentence (2) shall be determined from the actual or anticipated weight of the partitions placed in any probable position, but shall be not less than 1 kPa over the area of floor being considered.

(4) Partition loads used in design shall be shown on the drawings.

(5) In cases where the dead load of the partition is counteractive, the load allowances referred to in Sentences (2) and (3) shall not be included in the design calculations.

(6) Except for structures where the dead load of soil is part of the load-resisting system, where the dead load due to soil, superimposed earth, plants and trees is counteractive, it shall not be included in the design calculations.

(1) Except as provided in Sentence (2), the specified live load on an area of floor or roof depends on the intended use and occupancy, and shall not be less than the uniformly distributed load patterns in Article 4.1.5.3.v1, the loads resulting from the intended use or the concentrated loads in Article 4.1.5.10., whichever produces the most critical effect.

(2) For buildings in the Low Importance Category as described in Table 4.1.2.1.B., a factor of 0.8 may be applied to the live load.

(1) Except as provided in Sentence (2), where the use of an area of floor or roof is not provided for in Article 4.1.5.3.v1, the specified live loads due to the use and occupancy of the area shall be determined from an analysis of the loads resulting from the weight of,

(a) the probable assembly of persons,

(b) the probable accumulation of equipment and furnishings, and

(c) the probable storage of materials.

(2) For buildings in the Low Importance Category as described in Table 4.1.2.1.B., a factor of 0.8 may be applied to the live load.

(1) The uniformly distributed live load shall be not less than the value listed in Table 4.1.5.3., which may be reduced as provided in Article 4.1.5.9., applied uniformly over the entire area, or on any portions of the area, whichever produces the most critical effects in the members concerned.

(1) The following shall be designed to carry not less than the specified load required for the occupancy they serve, provided they cannot be used by an assembly of people as a viewing area:

(a) corridors, lobbies and aisles not more than 1 200 mm wide,

(b) all corridors above the first storey of residential areas of apartments, hotels and motels, and

(c) interior balconies and mezzanines.

(1) Exterior areas accessible to vehicular traffic shall be designed for their intended use, including the weight of fire fighting equipment, but not for less than the snow and rain loads prescribed in Subsection 4.1.6.

(2) Except as provided in Sentences (3) and (4), roofs shall be designed for the uniform live loads specified in Table 4.1.5.3.v1, the concentrated live loads listed in Table 4.1.5.10., or the snow and rain loads prescribed in Subsection 4.1.6., whichever produces the most critical effects in the members concerned.

(3) Exterior areas accessible to pedestrian traffic, but not vehicular traffic, shall be designed for their intended use, but not less than the greater of,

(a) the live load prescribed for assembly areas in Table 4.1.5.3.v1, or

(b) the snow, and rain prescribed in Subsection 4.1.6.

(4) Roof parking decks shall be designed for the uniformly distributed live loads specified in Table 4.1.5.3.v1, the concentrated live loads listed in Table 4.1.5.10., or the roof snow load, whichever produces the most critical effect in the members concerned.

(1) The minimum specified live load listed in Table 4.1.5.3.v1 for dining areas may be reduced to 2.4 kPa for areas in buildings that are being converted to dining areas, provided that the floor area does not exceed 100 m² and the dining area will not be used for other assembly purposes, including dancing.

(1) Equipment areas and service rooms, factories, storage areas and warehouses shall be designed for the live loads due to their intended use but not less than the specified loads listed in Table 4.1.5.3.v1

(1) Where an area of floor or roof is intended for 2 or more occupancies at different times, the value to be used from Table 4.1.5.3.v1 shall be the greatest value for any of the occupancies concerned.

(1) An area used for assembly occupancies designed for a live load of less than 4.8 kPa and roofs designed for the minimum loading specified in Table 4.1.5.3.v1 shall have no reduction for tributary area.

(2) Where a structural member supports a tributary area of a floor or a roof, or a combination of them, that is greater than 80 m² and either used for assembly occupancies designed for a live load of 4.8 kPa or more, or used for storage, manufacturing, retail stores, garages or as a footbridge, the specified live load due to use and occupancy is the load specified in Article 4.1.5.3.v1 multiplied by,

0.5 +

where A is the tributary area in square metres for this type of use and occupancy.

(3) Where a structural member supports a tributary area of a floor or a roof or a combination of them, that is greater than 20 m² and used for any use or occupancy other than assembly occupancies and those indicated in Sentences (1) and (2), the specified live load due to use and occupancy, is the load specified in Article 4.1.5.3.v1 multiplied by,

0.3 +

where B is the tributary area in square metres for this type of use and occupancy.

(4) Where the specified live load for a floor is reduced in accordance with Sentences (2) or (3), the structural drawings shall indicate that a live load reduction factor for tributary area has been applied.

(1) The specified live load due to possible concentrations of load resulting from the use of an area of floor or roof shall not be less than that listed in Table 4.1.5.10. applied over an area of 750 mm by 750 mm located so as to cause maximum effects, except that for occupancies not listed in Table 4.1.5.10., the concentrations of load shall be determined in accordance with Article 4.1.5.2.

(1) The floor assembly and other structural elements that support fixed seats in any building used for assembly occupancies accommodating large numbers of people at one time, such as grandstands, stadia and theatre balconies, shall be designed to resist a horizontal force equal to not less than 0.3 kN for each metre length of seats acting parallel to each row of seats, and not less then 0.15 kN for each metre length of seats acting at right angles to each row of seats, based on the assumption that these forces are acting independently of each other.

(1) The minimum specified load due to equipment, machinery or other objects that may produce impact shall be the sum of the weight of the equipment or machinery and its maximum lifting capacity, multiplied by an appropriate factor listed in Table 4.1.5.12.

(2) Crane runway structures shall be designed to resist a horizontal force applied normal to the top of the rails equal to not less than 20% of the sum of the weights of the lifted load and the crane trolley, excluding other parts of the crane.

(3) The force described in Sentence (2) shall be equally distributed on each side of the runway and shall be assumed to act in either direction.

(4) Crane runway structures shall be designed to resist a horizontal force applied parallel to the top of the rails equal to not less than 10% of the maximum wheel loads of the crane.

(1) Bleacher seats shall be designed for a uniformly distributed live load of 1.75 kN for each linear metre or for a concentrated load of 2.2 kN distributed over a length of 750 mm, whichever produces the most critical effect on the supporting members.

(2) Bleachers shall be checked by the erector after erection to ensure that all structural members, including bracing specified in the design, have been installed.

(3) Telescopic bleachers shall be provided with locking devices to ensure stability while in use.

(1) Helicopter landing areas on roofs shall be constructed in conformance with the requirements contained in “Canadian Aviation Regulations – Part III”, published by Transport Canada.

(1) The minimum specified horizontal load applied inward or outward at the top of every required guard shall be,

(a) 3.0 kN/m for means of egress in grandstands, stadia, bleachers and arenas,

(b) a concentrated load of 1.0 kN applied at any point for access ways to equipment platforms, contiguous stairs and similar areas where the gathering of many people is improbable, and

(c) 0.75 kN/m or a concentrated load of 1.0 kN applied at any point, whichever governs for locations other than those described in Clauses (a) and (b).

(2) Individual elements within the guard, including solid panels and pickets, shall be designed for a load of 0.5 kN applied over an area of 100 mm by 100 mm located at any point in the element or elements so as to produce the most critical effect.

(3) The loads required in Sentence (2) need not be considered to act simultaneously with the loads provided for in Sentences (1) and (4).

(4) The minimum specified load applied vertically at the top of every required guard shall be 15 kN/m and need not be considered to act simultaneously with the horizontal load provided for in Sentence (1).

(5) For loads on handrails, refer to Sentence 3.4.6.4.(9).

(1) Vehicle guardrails for storage garages shall be designed for a concentrated load of 22 kN applied horizontally outward at any point 500 mm above the floor surface.

(1) Where the floor elevation on one side of a wall, including a wall around a shaft, is more than 600 mm higher than the elevation of the floor or ground on the other side, the wall shall be designed to resist the appropriate lateral design loads prescribed elsewhere in this Section or 0.5 kPa, whichever produces the more critical effect.

(1) Firewalls shall be designed to resist the maximum effect due to,

(a) the appropriate lateral design loads prescribed elsewhere in this Section, or

(b) a factored lateral load of 0.5 kPa under fire conditions, as described in Sentence (2).

(2) Under fire conditions, where the fire-resistance rating of the structure is less than that of the firewall,

(a) lateral support shall be assumed to be provided by the structure on one side only, or

(b) another structural support system capable of resisting the loads imposed by a fire on either side of the firewall shall be provided.

(1) The specified load on a roof or any other building surface subject to snow and associated rain shall be the snow load specified in Article 4.1.6.2., or the rain load specified in Article 4.1.6.4., whichever produces the more critical effect.

(1) The specified load, S, due to snow and associated rain accumulation on a roof or any other building surface subject to snow accumulation shall be calculated from the formula,

S = I_s [S_s (C_bC_wC_sC_a) + S_r]

where,

I_s = importance factor for snow load as provided in Table 4.1.6.2.,

S_s = 1-in-50-year ground snow load, in kPa, determined in accordance with Subsection 1.1.2.,

C_b = basic roof snow load factor in Sentence (2),

C_w = wind exposure factor in Sentences (3) and (4),

C_s = slope factor in Sentences (5), (6) and (7),

C_a = shape factor in Sentence (8), and

S_r = 1-in-50-year associated rain load, in kPa, determined in accordance with Subsection 1.1.2., but not greater than S_s(C_bC_wC_sC_a).

(2) The basic roof snow load factor, C_b, shall be 0.8, except that for large roofs it shall be,

(a) 1.0 – (30/l_c)², for roofs with C_w = 1.0 and l_c greater than or equal to 70 m, or

(b) 1.3 – (140/l_c)², for roofs with C_w = 0.75 or 0.5 and l_c greater than or equal to 200 m,

where,

l_c = characteristic length of the upper or lower roof, defined as 2w-w²/l, in metres,

w = smaller plan dimension of the roof, in metres,

l = larger plan dimension of the roof, in metres.

(3) Except as provided for in Sentence (4), the wind exposure factor, C_w, shall be 1.0.

(4) For buildings in the Low and Normal Importance Categories as set out in Table 4.1.2.1.B., the wind exposure factor given in Sentence (3) may be reduced to 0.75, or to 0.5 in exposed areas north of the treeline, where,

(a) the building is exposed on all sides to wind over open terrain as defined in Clause 4.1.7.1.(5)(a) , and is expected to remain so during its life,

(b) the area of roof under consideration is exposed to the wind on all sides with no significant obstructions on the roof, such as parapet walls, within a distance of at least 10 times the difference between the height of the obstruction and C_bC_wS_s/γ metres, where γ is the unit weight of snow on roofs, and

(c) the loading does not involve the accumulation of snow due to drifting from adjacent surfaces.

(5) Except as provided for in Sentences (6) and (7), the slope factor, C_s, shall be,

(a) 1.0 where the roof slope, α, is equal to or less than 30°,

(b) (70° - α)/40° where α is greater than 30° but not greater than 70°, and

(c) 0 where α exceeds 70°.

(6) The slope factor, C_s, for unobstructed slippery roofs where snow and ice can slide completely off the roof shall be,

(a) 1.0 when the roof slope, α, is equal to or less than 15°,

(b) (60° - α)/45° when α is greater than 15°, but not greater than 60°, and

(c) 0 when α exceeds 60°.

(7) The slope factor, C_s, shall be 1.0 when used in conjunction with shape factors for increased snow loads as given in Clauses (8)(b) and (e).

(8) The shape factor, C_a, shall be 1.0, except that where appropriate for the shape of the roof, it shall be assigned other values that account for,

(a) non-uniform snow loads on gable, arched or curved roofs and domes,

(b) increased snow loads in valleys,

(c) increased non-uniform snow loads due to snow drifting onto a roof that is at a level lower than other parts of the same building or at a level lower than another building within 5 m of it,

(d) increased non-uniform snow loads on areas adjacent to roof projections, such as penthouses, large chimneys and equipment, and

(e) increased snow or ice loads due to snow sliding or meltwater draining from adjacent roofs.

(1) A roof or other building surface and its structural members subject to loads due to snow accumulation shall be designed for the specified load in Sentence 4.1.6.2.(1), distributed over the entire loaded area.

(2) In addition to the distribution in Sentence (1), flat roofs and shed roofs, gable roofs of 15° slope or less, and arched or curved roofs shall be designed for the specified uniform snow load indicated in Sentence 4.1.6.2.(1), which shall be calculated using C_a = 1.0, distributed on any one portion of the loaded area, and half of this load on the remainder of the loaded area, in such a way as to produce the most critical effects on the member concerned.

(1) Except as provided in Sentence (4), the specified load, S, due to the accumulation of rainwater on a surface whose position, shape and deflection under load make such an accumulation possible, is that resulting from the one-day rainfall determined in conformance with Subsection 1.1.2. and applied over the horizontal projection of the surface and all tributary surfaces.

(2) The provisions of Sentence (1) apply whether or not the surface is provided with a means of drainage, such as rain water leaders.

(3) Except as provided for in Sentence 4.1.6.2.(1), loads due to rain need not be considered to act simultaneously with loads due to snow.

(4) Where scuppers are provided and where the position, shape and deflection of the loaded surface make an accumulation of rainwater possible, the loads due to rain shall be the lesser of either the one-day rainfall determined in conformance with Subsection 1.1.2. or a depth of rainwater equal to 30 mm above the level of the scuppers, applied over the horizontal projection of the surface and tributary areas.

(1) The specified external pressure or suction due to wind on part or all of a surface of a building shall be calculated using the following formula:

p = I_wqC_eC_gC_p

where,

p = the specified external pressure acting statically and in a direction normal to the surface, either as a pressure directed towards the surface or as a suction directed away from the surface,

I_w = importance factor for wind load, as provided in Table 4.1.7.1.

q = the reference velocity pressure as provided for in Sentence (4),

C_e = the exposure factor as provided for in Sentence (5),

C_g = the gust effect factor, as provided for in Sentence (6), and

C_p = the external pressure coefficient averaged over the area of the surface considered.

(2) The net wind load for the building as a whole shall be the algebraic difference of the loads on the windward and the leeward surfaces, and in some cases may be calculated as the sum of the products of the external pressures or suctions and the areas of the surfaces over which they are averaged as provided in Sentence (1).

(3) The net specified pressure due to wind on part or all of a surface of a building shall be the algebraic difference of the external pressure or suction as provided for in Sentence (1) and the specified internal pressure or suction due to wind calculated from,

p_i = I_wqC_eC_giC_pi

where,

p_i = specified internal pressure acting statically and in a direction normal to the surface, either as a pressure directed toward the surface or as a suction directed away from the surface,

I_w = importance factor for wind load, as provided in Table 4.1.7.1.

q = the reference velocity pressure, as provided for in Sentence (4),

C_e = the exposure factor, as provided for in Sentence (5),

C_gi = internal gust effect factor, as provided for in Sentence (6), and

C_pi = the internal pressure coefficient.

(4) The reference velocity pressure, q, shall be the appropriate value determined in conformance with Subsection 1.1.2. based on a probability of being exceeded in any one year of 1-in-50.

(5) The exposure factor C_e, shall be,

(a) (h/10)^0.2 but not less than 0.9 for open terrain, where open terrain is level terrain with only scattered buildings, trees or other obstructions, open water or shorelines, h being the reference height above grade in metres for the surface or part of the surface,

(b) 0.7(h/12)^0.3 but not less than 0.7 for rough terrain, where rough terrain is suburban, urban or wooded terrain extending upwind from the building uninterrupted for at least 1 km or 10 times the building height, whichever is greater, h being the reference height above grade in metres for the surface or part of the surface,

(c) an intermediate value between the two exposures defined in Clauses (a) and (b) in cases where the site is less than 1 km or 10 times the building height from a change in terrain conditions, whichever is greater, provided an appropriate interpolation method is used, or

(d) if a dynamic approach to the action of wind gusts is used, an appropriate value depending on both height and shielding.

(6) The gust effect factor, C_g, shall be one of the following values:

(a) for the building as a whole and main structural members, C_g = 2.0,

(b) for external pressures and suctions on small elements including cladding, C_g = 2.5,

(c) for internal pressures, C_gi = 2.0 or a value determined by detailed calculation that takes into account the sizes of the openings in the building envelope, the internal volume and the flexibility of the building envelope, or

(d) if a dynamic approach to wind action is used, C_g is a value that is appropriate for the turbulence of the wind and the size and natural frequency of the structure.

(1) Buildings whose height is greater than 4 times their minimum effective width, which is defined in Sentence (2), or greater than 120 m and other buildings whose light weight, low frequency and low damping properties make them susceptible to vibration shall be designed by,

(a) experimental methods for the danger of dynamic overloading, vibration and the effects of fatigue, or

(b) using a dynamic approach to the action of wind gusts.

(2) The effective width, w, of a building shall be calculated using the formula,

where,

the summations are over the height of the building for a given wind direction,

h_i is the height above grade to level i, as defined in Sentence 4.1.7.1.(5), and

w_i is the width normal to the wind direction at height h_i,

the minimum effective width is the lowest value of the effective width considering all possible wind directions.

(1) Buildings and structural members shall be capable of withstanding the effects of,

(a) the full wind loads acting along each of the two principal horizontal axes considered separately,

(b) the wind loads as described in Clause (a) but with 100% of the load removed from any portion of the area,

(c) the wind loads as in Clause (a) but considered simultaneously at 75% of their full value, and

(d) the wind loads as described in Clause (c) but with 50% of these loads removed from any portion of the area.

(1) In the design of interior walls and partitions, due consideration shall be given to differences in air pressure on opposite sides of the wall or partition that may result from,

(a) pressure differences between the windward and leeward sides of a building,

(b) stack effects due to a difference in air temperature between the exterior and interior of the building, and

(c) air pressurization by the mechanical services of the building.

(1) The deflections and specified loading due to earthquake motions shall be determined according to the requirements in this Subsection, except that the requirements in this Subsection need not be considered in design if S(0.2), as defined in Sentence 4.1.8.4.(6), is less than or equal to 0.12.

(1) In this Subsection,

A_r = response amplification factor to account for type of attachment of mechanical/electrical equipment, as defined in Sentence 4.1.8.17.(1)v1,

A_x = amplification factor at level x to account for variation of response of mechanical/electrical equipment with elevation within the building, as defined in Sentence 4.1.8.17.(1)v1,

B_x = ratio at level x used to determine torsional sensitivity, as defined in Sentence 4.1.8.11.(9)v1,

B = maximum value of B_x, as defined in Sentence 4.1.8.11.(9)v1,

C_p = seismic coefficient for mechanical/electrical equipment, as defined in Sentence 4.1.8.17.(1)v1,

D_nx = plan dimension of the building at level x perpendicular to the direction of seismic loading being considered,

e_x = distance measured perpendicular to the direction of earthquake loading between centre of mass and centre of rigidity at the level being considered,

F_a = acceleration-based site coefficient, as defined in Sentence 4.1.8.4.(4),

F_t = portion of V to be concentrated at the top of the structure, as defined in Sentence 4.1.8.11.(6)v1,

F_v = velocity-based site coefficient, as defined in Sentence 4.1.8.4.(4),

F_x = lateral force applied to level x, as defined in Sentence 4.1.8.11.(6)v1,

h_i, h_n, h_x = the height above the base (i = 0) to level i, n, or x respectively, where the base of the structure is the level at which horizontal earthquake motions are considered to be imparted to the structure,

h_s = interstorey height (h_i - h_i-1),

I_E = earthquake importance factor of the structure, as described in Sentence 4.1.8.5.(1),

J = numerical reduction coefficient for base overturning moment, as defined in Sentence 4.1.8.11.(5)v1

J_X = numerical reduction coefficient for overturning moment at level x, as defined in Sentence 4.1.8.11.(7)v1,

Level i = any level in the building, i =1 for first level above the base,

Level n = level that is uppermost in the main portion of the structure,

Level x = level that is under design consideration,

M_v = factor to account for higher mode effect on base shear, as defined in Sentence 4.1.8.11.(5)v1,

M_x = overturning moment at level x, as defined in Sentence 4.1.8.11.(7)v1,

N = total number of storeys above exterior grade to level n,

₆₀ = Average Standard Penetration Resistance for the top 30 m, corrected to a rod energy efficiency of 60% of the theoretical maximum,

PGA = Peak Ground Acceleration expressed as a ratio to gravitational acceleration, as defined in Sentence 4.1.8.4.(1),

PI = plasticity index for clays,

R_d = ductility-related force modification factor reflecting the capability of a structure to dissipate energy through inelastic behaviour, as given in Article 4.1.8.9.,

R_o = overstrength-related force modification factor accounting for the dependable portion of reserve strength in a structure designed according to these provisions, as defined in Article 4.1.8.9.,

S_P = horizontal force factor for part or portion of a building and its anchorage, as given in Sentence 4.1.8.17.(1)v1,

S(T) = design spectral response acceleration, expressed as a ratio to gravitational acceleration, for a period of T, as defined in Sentence 4.1.8.4.(6),

S_a(T) = 5% damped spectral response acceleration, expressed as a ratio to gravitational acceleration, for a period of T, as defined in Sentence 4.1.8.4.(1),

SFRS = Seismic Force Resisting System(s) is that part of the structural system that has been considered in the design to provide the required resistance to the earthquake forces and effects defined in Subsection 4.1.8.,

s_u = average undrained shear strength in the top 30 m of soil,

T = period in seconds,

T_a = fundamental lateral period of vibration of the building or structure in seconds in the direction under consideration, as defined in Sentence 4.1.8.11.(3)v1,

T_x = floor torque at level x, as defined in Sentence 4.1.8.11.(10)v1,

V = lateral earthquake design force at the base of the structure, as determined by Article 4.1.8.11.v1,

V_d = lateral earthquake design force at the base of the structure, as determined by Article 4.1.8.12.,

V_e = lateral earthquake elastic force at the base of the structure, as determined by Article 4.1.8.12.,

V_P = lateral force on a part of the structure, as determined by Article 4.1.8.17.v1,

_S = average shear wave velocity in the top 30 m of soil or rock,

W = dead load, as defined in Article 4.1.4.1., except that the minimum partition load as defined in Sentence 4.1.4.1.(3) need not exceed 0.5 kPa, plus 25% of the design snow load specified in Subsection 4.1.6., plus 60% of the storage load for areas used for storage, except that storage garages need not be considered storage areas, and the full contents of any tanks,

W_i, W_x = portion of W that is located at or is assigned to level i or x respectively,

W_P = weight of a part or portion of a structure, e.g., cladding, partitions and appendages,

δ_ave = average displacement of the structure at level x, as defined in Sentence 4.1.8.11.(9)v1, and

δ_max = maximum displacement of the structure at level x, as defined in Sentence 4.1.8.11.(9)v1.

(1) The building shall be designed to meet the requirements of this Subsection and of the design standards referenced in Section 4.3.

(2) Structures shall be designed with a clearly defined load path, or paths, that will transfer the inertial forces generated in an earthquake to the supporting ground.

(3) The structure shall have a clearly defined Seismic Force Resisting System(s) (SFRS), as defined in Article 4.1.8.2.

(4) The SFRS shall be designed to resist 100% of the earthquake loads and their effects.

(5) All structural framing elements not considered to be part of the SFRS must be investigated and shown to behave elastically or to have sufficient non-linear capacity to support their gravity loads while undergoing earthquake-induced deformations calculated from the deflections determined in Article 4.1.8.13.

(6) Stiff elements that are not considered part of the SFRS, such as concrete, masonry, brick or pre-cast walls or panels, shall be,

(a) separated from all structural elements of the building such that no interaction takes place as the building undergoes deflections due to earthquake effects as calculated in this Subsection, or

(b) made part of the SFRS and satisfy the requirements of this Subsection.

(7) Stiffness imparted to the structure from elements not part of the SFRS, other than those described in Sentence (6), shall not be used to resist earthquake deflections but shall be accounted for,

(a) in calculating the period of the structure for determining forces if the added stiffness decreases the fundamental lateral period by more than 15%,

(b) in determining the irregularity of the structure, except the additional stiffness shall not be used to make an irregular SFRS regular or to reduce the effects of torsion, and

(c) in designing the SFRS if inclusion of the elements not part of the SFRS in the analysis has an adverse effect on the SFRS.

(8) Structural modelling shall be representative of the magnitude and spatial distribution of the mass of the building and of the stiffness of all elements of the SFRS, including stiff elements that are not separated in accordance with Sentence 4.1.8.3.(6), and shall account for,

(a) the effect of cracked sections in reinforced concrete and reinforced masonry elements,

(b) the effect of the finite size of members and joints,

(c) sway effects arising from the interaction of gravity loads with the displaced configuration of the structure, and

(d) other effects that influence the lateral stiffness of the building.

(1) The peak ground acceleration (PGA) and the 5% damped spectral response acceleration values, S_a(T), for the reference ground conditions (Site Class C in Table 4.1.8.4.A.) for periods T of 0.2 s, 0.5 s, 1.0 s, and 2.0 s, shall be determined in accordance with Subsection 1.1.2. and are based on a 2% probability of exceedance in 50 years.

(2) Site classifications for ground shall conform to Table 4.1.8.4.A. and shall be determined using _S except as provided in Sentence (3).

(3) If average shear wave velocity, _S, is not known, Site Class shall be determined from energy-corrected Average Standard Penetration Resistance, ₆₀, or from soil average undrained shear strength, s_u, as noted in Table 4.1.8.4.A.,₆₀ and s_u being calculated based on rational analysis.

(4) Acceleration- and velocity-based site coefficients, F_a and F_v, shall conform to Tables 4.1.8.4.B. and 4.1.8.4.C. using linear interpolation for intermediate values of S_a(0.2) and S_a(1.0).

(5) To determine F_a and F_v for Site Class F, site-specific geotechnical investigations and dynamic site response analysis shall be performed.

(6) The design spectral acceleration values of S(T) shall be determined as follows, using linear interpolation for intermediate values of T:

S(T) = F_aS_a(0.2) for T≤0.2 s

= F_vS_a(0.5) or F_aS_a(0.2), whichever is smaller for T = 0.5 s

= F_vS_a(1.0) for T = 1.0 s

= F_vS_a(2.0) for T = 2.0 s

= F_vS_a(2.0)/2 for T ≥4.0 s

(1) The earthquake importance factor, I_E, shall be determined according to Table 4.1.8.5.

(1) Structures having any of the features listed in Table 4.1.8.6. shall be designated irregular.

(2) Structures not classified as irregular according to Sentence 4.1.8.6.(1) may be considered regular.

(3) Except as required by Article 4.1.8.10., in cases where I_EF_aS_a(0.2) is equal to or greater than 0.35, structures designated as irregular must satisfy the provisions referenced in Table 4.1.8.6.

(1) Analysis for design earthquake actions shall be carried out in accordance with the Dynamic Analysis Procedure described in Article 4.1.8.12., except that the Equivalent Static Force Procedure described in Article 4.1.8.11.v1 may be used for structures that meet any of the following criteria:

(a) in cases where I_EF_aS_a(0.2) is less than 0.35,

(b) regular structures that are less than 60 m in height and have a fundamental lateral period, T_a, less than 2 s in each of two orthogonal directions as defined in Article 4.1.8.8., or

(c) structures with structural irregularity, of Type 1, 2, 3, 4, 5, 6 or 8 as defined in Table 4.1.8.6.v1, that are less than 20 m in height and have a fundamental lateral period, T_a, less than 0.5 s in each of two orthogonal directions as defined in Article 4.1.8.8.

(1) Earthquake forces shall be assumed to act in any horizontal direction, except that the following shall be considered to provide adequate design force levels in the structure:

(a) where components of the SFRS are oriented along a set of orthogonal axes, independent analyses about each of the principal axes of the structure shall be performed,

(b) where the components of the SFRS are not oriented along a set of orthogonal axes and I_EF_aS_a(0.2) is less than 0.35, independent analyses about any two orthogonal axes is permitted, or

(c) where the components of the SFRS are not oriented along a set of orthogonal axes and I_EF_aS_a(0.2) is equal to or greater than 0.35, analysis of the structure independently in any two orthogonal directions for 100% of the prescribed earthquake loads applied in one direction plus 30% of the prescribed earthquake loads in the perpendicular direction, with the combination requiring the greater element strength being used in the design.

(1) The values of R_d and R_o and the corresponding system restrictions shall conform to Table 4.1.8.9. and the requirements of this Subsection.

(2) When a particular va1ue of R_d is required by this Article, the corresponding R_o shall be used.

(3) For combinations of different types of SFRS acting in the same direction in the same storey, R_dR_o shall be taken as the lowest value of R_dR_o corresponding to these systems.

(4) For vertical variations of R_dR_o, excluding penthouses whose weight is less than 10% of the level below, the value of R_dR_o used in the design of any storey shall be less than or equal to the lowest value of R_dR_o used in the given direction for the storeys above, and the requirements of Sentence 4.1.8.15.(3) must be satisfied.

(5) If it can be demonstrated through testing, research and analysis that the seismic performance of a structural system is at least equivalent to one of the types of SFRS mentioned in Table 4.1.8.9., then such a structural system will qualify for values of R_d and R_o corresponding to the equivalent type in that Table.

(1) Except as required by Clause (2)(b), structures with a Type 6 irregularity, Discontinuity in Capacity – Weak Storey, as described in Table 4.1.8.6.v1, are not permitted unless I_EF_aS_a(0.2) is less than 0.2 and the forces used for design of the SFRS are multiplied by R_dR_o.

(2) Post disaster buildings shall,

(a) not have any irregularities conforming to Types 1, 3, 4, 5 and 7 as described in Table 4.1.8.6.v1, in cases where I_EF_aS_a(0.2) is equal to or greater than 0.35,

(b) not have a Type 6 irregularity as described in Table 4.1.8.6.v1, and

(c) have an SFRS with an R_d of 2.0 or greater.

(3) For buildings having fundamental lateral periods, T_a, of 1.0 s or greater, and where I_EF_vS_a(1.0) is greater than 0.25, walls forming part of the SFRS shall be continuous from their top to the foundation and shall not have irregularities of Type 4 or 5 as described in Table 4.1.8.6.v1

(1) The static loading due to earthquake motion shall be determined according to the procedures given in this Article.

(2) The minimum lateral earthquake force, V, shall be calculated using the formula,

V = S (T_a) M_vI_EW/ (R_dR_o)

except that V shall not be less than,

S (2.0) M_v I_EW/ (R_dR_o)

and for an SFRS with an R_d equal to or greater than 1.5, V need not be greater than,

(3) The fundamental lateral period, T_a, in the direction under consideration in Sentence (2) shall be determined as,

(a) for moment resisting frames that resist 100% of the required lateral forces and where the frame is not enclosed by or adjoined by more rigid elements that would tend to prevent the frame from resisting lateral forces, and where h_n is in metres,

(i) 0.085 (h_n)^3/4 for steel moment frames,

(ii) 0.075 (h_n)^3/4 for concrete moment frames, or

(iii) 0.1 N for other moment frames,

(b) 0.025h_n for braced frames where h_n is in metres,

(c) 0.05 (h_n)^3/4 for shear wall and other structures where h_n is in metres, or

(d) other established methods of mechanics using a structural model that complies with the requirements of Sentence 4.1.8.3.(8), except that,

(i) for moment resisting frames, T_a shall not be taken greater than 1.5 times that determined in Clause (a),

(ii) for braced frames, T_a shall not be taken greater than 2.0 times that determined in Clause (b),

(iii) for shear wall structures, T_a shall not be greater than 2.0 times that determined in Clause (c), and

(iv) for the purpose of calculating the deflections, the period without the upper limit specified herein may be used.

(4) The weight, W, of the building shall be calculated using the formula,

(5) The higher mode factor, M_v, and its associated base overturning moment reduction factor, J, shall conform to Table 4.1.8.11.

(6) The total lateral seismic force, V, shall be distributed such that a portion, F_t, shall be assumed to be concentrated at the top of the building, where F_t, is equal to 0.07 T_aV but need not exceed 0.25 V and may be considered as zero, where the fundamental lateral period, T_a, does not exceed 0.7 s; the remainder, V - F_t, shall be distributed along the height of the building, including the top level, in accordance with the formula,

(7) The structure shall be designed to resist overturning effects caused by the earthquake forces determined in Sentence (6) and the overturning moment at level x, M_x, shall be determined using the formula,

where,

J_x = 1.0 for h_x ≥ 0.6h_n, and

J_x = J + (1- J)(h_x / 0.6h_n) for h_x,< 0.6h_n

where,

J = base overturning moment reduction factor conforming to Table 4.1.8.11.

(8) Torsional effects that are concurrent with the effects of the forces mentioned in Sentence (6) and are caused by the following torsional moments shall be considered in the design of the structure according to Sentence (10):

(a) torsional moments introduced by eccentricity between the centres of mass and resistance and their dynamic amplification, or

(b) torsional moments due to accidental eccentricities.

(9) Torsional sensitivity shall be determined by calculating the ratio B_x for each level x according to the following equation for each orthogonal direction determined independently:

B_x = δ_max / δ_ave

where,

B = maximum of all values of B_x in both orthogonal directions, except that the B_x for one-storey penthouses with a weight less than 10% of the level below need not be considered,

δ_max = maximum storey displacement at the extreme points of the structure, at level x in the direction of the earthquake induced by the equivalent static forces acting at distances ± 0.10 D_nx from the centres of mass at each floor, and

δ_ave = average of the displacements at the extreme points of the structure at level x produced by the above mentioned forces.

(10) Torsional effects shall be accounted for as follows:

(a) for a building with B ≤1.7, by applying torsional moments about a vertical axis at each level throughout the building derived for each of the following load cases considered separately,

(i) T_x = F_x(e_x + 0.10 D_nx), and

(ii) T_x = F_x(e_x – 0.10 D_nx)

where F_x is the lateral force at each level determined according to Sentence (6) and where each element of the building is designed for the most severe effect of the above load cases, or

(b) for a building with B ≥1.7, in cases where I_EF_aS_a(0.2) is equal to or greater than 0.35, by a Dynamic Analysis Procedure as specified in Article 4.1.8.12.

(1) The Dynamic Analysis Procedure shall be in accordance with one of the following methods:

(a) Linear Dynamic Analysis by either the Modal Response Spectrum Method or the Numerical Integration Linear Time History Method using a structural model that complies with the requirements of Sentence 4.1.8.3.(8), or

(b) Nonlinear Dynamic Analysis, in which case a special study shall be performed.

(2) The spectral acceleration values used in the Modal Response Spectrum Method shall be the design spectral acceleration values, S(T), defined in Sentence 4.1.8.4.(6).

(3) The ground motion histories used in the Numerical Integration Linear Time History Method shall be compatible with a response spectrum constructed from the design spectral acceleration values, S(T), defined in Sentence 4.1.8.4.(6).

(4) The effects of accidental torsional moments acting concurrently with the lateral earthquake forces that cause them shall be accounted for by the following methods:

(a) the static effects of torsional moments due to (± 0.10 D_nx)F_x at each level x, where F_x is determined from Sentence 4.1.8.11.(6)v1 or from the dynamic analysis, shall be combined with the effects determined by dynamic analysis, or

(b) if B, as defined in Sentence 4.1.8.11.(9)v1, is less than 1.7, it is permitted to use a three-dimensional dynamic analysis with the centres of mass shifted by a distance of – 0.05 D_nx and + 0.05 D_nx,

(5) The elastic base shear, V_e, obtained from a Linear Dynamic Analysis shall be multiplied by the importance factor, I_E, as determined in Article 4.1.8.5., and shall be divided by R_dR_o, as determined in Article 4.1.8.9., to obtain the base shear, V_d.

(6) Except as required by Sentence (7), if the base shear, V_d, obtained in Sentence (5) is less than 80% of the lateral earthquake design force, V, of Article 4.1.8.11.v1, V_d shall be taken as 0.8 V.

(7) For irregular structures requiring dynamic analysis in accordance with Article 4.1.8.7., V_d shall be taken as the larger of the V_d determined in Sentence (5) and 100% of V.

(8) Except as required by Sentence (9), the values of elastic storey shears, storey forces, member forces, and deflections obtained from the Linear Dynamic Analysis shall be multiplied by V_d/V_e to determine their design values, where V_d is the base shear.

(9) For the purpose of calculating deflections, it is permitted to use a value for V based on the value for T_a determined in Clause 4.1.8.11.(3)(d)v1 to obtain V_d in Sentences (6) and (7).

(1) Lateral deflections of a structure shall be calculated in accordance with the loads and requirements defined in this Subsection.

(2) Lateral deflections obtained from a linear elastic analysis using the methods given in Articles 4.1.8.11.v1 and 4.1.8.12. and incorporating the effects of torsion, including accidental torsional moments, shall be multiplied by R_dR_o/I_E to give realistic values of anticipated deflections.

(3) Based on the lateral deflections calculated in Sentence (2), the largest interstorey deflection at any level shall be limited to 0.01 h_s for post-disaster buildings, 0.02 h_s for schools, and 0.025 h_s for all other buildings.

(4) The deflections calculated in Sentence (2) shall be used to account for sway effects as required by Sentence 4.1.3.2.(10)v1.

(1) Adjacent structures shall either be separated by the square root of the sum of the squares of their individual deflections calculated in Sentence 4.1.8.13.(2), or shall be connected to each other.

(2) The method of connection required in Sentence (1) shall take into account the mass, stiffness, strength, ductility and anticipated motion of the connected buildings and the character of the connection.

(3) Rigidly connected buildings shall be assumed to have the lowest R_dR_o value of the buildings connected.

(4) Buildings with non-rigid or energy-dissipating connections require special studies.

(1) Diaphragms and their connections shall be designed so as not to yield, and the design shall account for the shape of the diaphragm, including openings, and for the forces generated in the diaphragm due to the following cases, whichever one governs:

(a) forces due to loads determined in Articles 4.1.8.11.v1 or 4.1.8.12. applied to the diaphragm are increased to reflect the lateral load capacity of the SFRS, plus forces in the diaphragm due to the transfer of forces between elements of the SFRS associated with the lateral load capacity of such elements and accounting for discontinuities and changes in stiffness in these elements, or

(b) a minimum force corresponding to the design-based shear divided by N for the diaphragm at level x.

(2) In cases where I_EF_aS_a(0.2) is equal to or greater than 0.35, the elements supporting any discontinuous wall, column or braced frame shall be designed for the lateral load capacity of the components of the SFRS they support.

(3) Where structures have vertical variations of R_dR_o satisfying Sentence 4.1.8.9.(4), the elements of the SFRS below the level where the change in R_dR_o occurs shall be designed for the forces associated with the lateral load capacity of the SFRS above that level.

(4) Where earthquake effects can produce forces in a column or wall due to lateral loading along both orthogonal axes, account shall be taken of the effects of potential concurrent yielding of other elements framing into the column or wall from all directions at the level under consideration and as appropriate at other levels.

(5) Except as provided in Sentence (6), the design forces need not exceed the forces determined in accordance with Sentence 4.1.8.7.(1), multiplied by R_dR_o.

(6) If foundation rocking is accounted for, the design forces for the SFRS need not exceed the maximum values associated with foundation rocking, provided that R_d and R_o for the type of SFRS used conform to Table 4.1.8.9. and that the foundation is designed in accordance with Sentence 4.1.8.16.(1).

(1) Foundations shall be designed to resist the lateral load capacity of the SFRS, except that when the foundations are allowed to rock, the design forces for the foundation need not exceed those determined in Sentence 4.1.8.7.(1) using an R_dR_o equal to 2.0.

(2) The design of foundations shall be such that they are capable of transferring earthquake loads and effects between the building and the ground without exceeding the capacities of the soil and rock.

(3) In cases where I_EF_aS_a(0.2) is equal to or greater than 0.35, the following requirements shall be satisfied:

(a) piles or pile caps, drilled piers, and caissons shall be interconnected by continuous ties in no fewer than two directions,

(b) piles, drilled piers, and caissons shall be embedded a minimum of 100 mm into the pile cap or structure, and

(c) piles, drilled piers, and caissons, other than wood piles, shall be connected to the pile cap or structure for a minimum tension force equal to 0.15 times the factored compression load on the pile.

(4) At sites where I_EF_aS_a(0.2) is equal to or greater than 0.35, basement walls shall be designed to resist earthquake lateral pressures from backfill or natural ground.

(5) At sites where I_EF_aS_a(0.2) is greater than 0.75, the following requirements shall be satisfied:

(a) piles, drilled piers, or caissons shall be designed and detailed to accommodate cyclic inelastic behaviour when the design moment in the element due to earthquake effects is greater than 75% of its moment capacity, and

(b) spread footings founded on soil defined as Site Class E or F shall be interconnected by continuous ties in no fewer than two directions.

(6) Each segment of a tie between elements that is required by Clauses (3)(a) or (5)(b) shall be designed to carry by tension or compression a horizontal force at least equal to the greatest factored pile cap or column vertical load in the elements it connects, multiplied by a factor of 0.10 I_EF_aS_a(0.2), unless it can be demonstrated that equivalent restraints can be provided by other means.

(7) The potential for liquefaction of the soil and its consequences, such as significant ground displacement and loss of soil strength and stiffness, shall be evaluated based on the ground motion parameters referenced in Subsection 1.1.2. and shall be taken into account in the design of the structure and its foundations.

(1) Except as provided in Sentences (2) and (8), elements and components of buildings described in Table 4.1.8.17. and their connections to the structure shall be designed to accommodate the building deflections calculated in accordance with Article 4.1.8.13. and the element or component deflections calculated in accordance with Sentence (10), and shall be designed for a lateral force, V_P, applied through the centre of mass of the element or component that is equal to:

V_p= 0.3F_aS_a(0.2) I_ES_pW_p

where,

F_a = as defined in Table 4.1.8.4.B.,

S_a(0.2) = spectral response acceleration value at 0.2 s, as defined in Sentence 4.1.8.4.(1),

I_E = importance factor for the building, as defined in Article 4.1.8.5.,

S_p = C_pA_rA_x/R_p (the maximum value of S_p shall be taken as 4.0 and the minimum value of S_p shall be taken as 0.7), where

C_p = element or component factor from Table 4.1.8.17.,

A_r = element or component force amplification factor from Table 4.1.8.17.,

A_x = height factor (1 + 2 h_x / h_n),

R_p = element or component response modification factor from Table 4.1.8.17., and

W_p = weight of the component or element.

(2) For buildings other than post-disaster buildings, where I_EF_aS_a(0.2) is less than 0.35, the requirements of Sentence (1) need not apply to Categories 6 through 21 of Table 4.1.8.17.

(3) The values of C_p in Sentence (1) shall conform to Table 4.1.8.17.

(4) For the purpose of applying Sentence (1) and Categories 11 and 12 of Table 4.1.8.17., elements or components shall be assumed to be flexible or flexibly connected unless it can be shown that the fundamental period of the element or component and its connection is less than or equal to 0.06 s, in which case the element or component is classified as being rigid or rigidly connected.

(5) The weight of access floors shall include the dead load of the access floor and the weight of permanent equipment, which shall not be taken as less than 25% of the floor live load.

(6) When the mass of a tank plus its contents is greater than 10% of the mass of the supporting floor, the lateral forces shall be determined by rational analysis.

(7) Forces shall be applied in the horizontal direction that results in the most critical loading for design, except for Category 6 of Table 4.1.8.17., where the forces shall be applied up and down vertically.

(8) Connections to the structure of elements and components listed in Table 4.1.8.17. shall be designed to support the component or element for gravity loads, shall conform to the requirements of Sentence (1), and shall also satisfy these additional requirements:

(a) friction due to gravity loads shall not be considered to provide resistance to seismic forces,

(b) R_p for non-ductile connections, such as adhesives or power actuated fasteners, shall be taken as 1.0,

(c) R_p for anchorage using shallow expansion, chemical, epoxy or cast-in place anchors shall be 1.5, where shallow anchors are those with a ratio of embedment length to diameter of less than 8,

(d) power-actuated fasteners and drop-in anchors shall not be used for tension loads,

(e) connections for non-structural elements or components of Categories 1, 2 or 3 of Table 4.1.8.17. attached to the side of a building and above the first level above grade shall satisfy the following requirements:

(i) for connections where the body of the connection is ductile, the body shall be designed for values of C_P, A_r and R_p given in Table 4.1.8.17., and the fasteners, such as anchors, welds, bolts and inserts, shall also be designed for values of C_p and A_r given in this Table, and R_p = 1.0, and

(ii) connections where the body of the connection is not ductile shall be designed for values of C_p=2.0, R_p =1.0 and A_r given in Table 4.1.8.17., and

(f) for the purpose of applying Clause (e), a ductile connection is one where the body of the connection yields at its design load.

(9) Floors and roofs acting as diaphragms shall satisfy the requirements for diaphragms stated in Article 4.1.8.15.

(10) Lateral deflections of elements or components shall be based on the loads defined in Sentence (1) and lateral deflections obtained from an elastic analysis shall be multiplied by R_p/I_E to give realistic values of the anticipated deflections.

(11) The elements or components shall be designed so as not to transfer to the structure any forces unaccounted for in the design, and rigid elements such as walls or panels shall satisfy the requirements of Sentence 4.1.8.3.(6).

(12) Seismic restraint for suspended equipment, pipes, ducts, electrical cable trays, etc. shall be designed to meet the force and displacement requirements of this Article and be constructed in a manner that will not subject hanger rods to bending.

(13) Isolated suspended equipment and components, such as pendant lights, maybe designed as a pendulum system provided that adequate chains or cables capable of supporting 2.0 times the weight of the suspended component are provided and the deflection requirements of Sentence (11) are satisfied.

(1) This Section applies to excavations and foundation systems for buildings.

(1) A subsurface investigation, including groundwater conditions, shall be carried out, by or under the direction of a person having knowledge and experience in planning and executing such investigations to a degree appropriate for the building and its use, the ground and the surrounding site conditions.

(1) A field review shall be carried out by the designer or by another suitably qualified person to ascertain that the subsurface conditions are consistent with the design and that construction is carried out in accordance with the design and good engineering practice.

(2) The review required in Sentence (1) shall be carried out,

(a) on a continuous basis,

(i) during the construction of all deep foundation units with all pertinent information recorded for each foundation unit,

(ii) during the installation and removal of retaining structures and related backfilling operations, and

(iii) during the placement of engineered fills that are to be used to support the foundation units, and

(b) as required, unless otherwise directed by the chief building official,

(i) in the construction of all shallow foundation units, and

(ii) in excavating, dewatering and other related works.

(1) If during construction, the soil, rock or groundwater is found not to be of the type or in the condition used in design, and as indicated on the drawings, the design shall be reassessed by the designer.

(2) If during construction, climatic or any other conditions have changed the properties of the soil, rock or groundwater, the design shall be reassessed by the designer.

(1) Wood used in foundations or in support of soil or rock shall conform to the appropriate requirements of Subsection 4.3.1.

(1) Wood exposed to soil or air above the lowest anticipated groundwater table shall be treated with preservative in conformance with CSA O80 Series, “Wood Preservation”, and the requirements of the appropriate commodity standard as follows:

(a) CSA-O80.2, “Preservative Treatment of Lumber, Timber, Bridge Ties and Mine Ties by Pressure Processes”,

(b) CSA-O80.3, “Preservative Treatment of Piles by Pressure Processes”, or

(c) CSA-O80.15, “Preservative Treatment of Wood for Building Foundation Systems, Basements and Crawl Spaces by Pressure Processes”.

(2) Where timber has been treated as required in Sentence (1), it shall be cared for as provided in AWPA-M4, “Care of Preservative-Treated Wood Products”, as revised by Clause 6 of CSA O80 Series, “Wood Preservation”.

(1) Plain or reinforced masonry used in foundations or in support of soil or rock shall conform to the requirements of Subsection 4.3.2.

(1) Where plain or reinforced masonry in foundations or in structures supporting soil or rock may be subject to conditions conducive to deterioration, protection shall be provided to prevent such deterioration.

(1) Plain, reinforced or prestressed concrete used in foundations or in support of soil or rock shall conform to the requirements of Subsection 4.3.3.

(1) Where concrete in foundations may be subject to chemical attack, it shall be treated in conformance with the requirements in CAN/CSA-A23.1, “Concrete Materials and Methods of Concrete Construction”.

(1) Steel used in foundations or in support of soil or rock shall conform with the appropriate requirements of Subsections 4.3.3. or 4.3.4., unless otherwise specified in this Section.

(1) Where steel piles are used in deep foundations and act as permanent load-carrying members, the steel shall conform with one of the following standards:

(a) ASTM A252, “Welded and Seamless Steel Pipe Piles”,

(b) ASTM A283 / A283M, “Low and Intermediate Tensile Strength Carbon Steel Plates”,

(c) ASTM A1008 / A1008M , “Steel, Sheet, Cold Rolled, Carbon, Structural,High-Strength Low-Alloy and High-Strength Low-Alloy with Improved Formability”,

(d) ASTM A1011 / A1011M, “Steel, Sheet and Strip, Hot Rolled, Carbon, Structural, High Strength Low Alloy and High Strength Low Alloy with Improved Formability”, or

(e) CAN/CSA-G40.21, “Structural Quality Steel”.

(1) Where high strength steel is used for tendons in anchor systems used for the permanent support of a foundation or in the erection of temporary support of soil or rock adjacent to an excavation, it shall conform with the requirements of CAN/CSA-A23.1, “Concrete Materials and Methods of Concrete Construction”.

(1) Where conditions are corrosive to steel, adequate protection of exposed steel shall be provided.

(1) The design of foundations, excavations and soil – and rock-retaining structures shall be based on a subsurface investigation carried out by a person competent in this field of work, and on any of the following:

(a) application of generally accepted geotechnical and civil engineering principles by a person especially qualified in this field of work as provided in this Section and other Sections of this Part,

(b) established local practice where such practice includes successful experience both with soils and rocks of similar type and condition and with a foundation or excavation of similar type, construction method, size and depth, or

(c) in situ testing of foundation units such as the load testing of piles, anchors or footings carried out by a person competent in this field of work.

(2) The foundations of a building shall be capable of resisting all the loads stipulated in Section 4.1., in accordance with limit states design in Subsection 4.1.3.

(3) For the purpose of the application of the load combinations given in Table 4.1.3.2.v1, the geotechnical components of loads and the factored geotechnical resistances at ULS shall be determined by a suitably qualified and experienced person.

(4) Geotechnical components of service loads and geotechnical reactions for SLS shall be determined by a suitably qualified and person.

(5) The foundation of a building shall be designed to satisfy SLS requirements within the limits that the building is designed to accommodate, including total settlement and differential settlement, heave, lateral movement, tilt or rotation.

(6) Communication, interaction and coordination between the designer and the person responsible for the geotechnical aspects of the project shall take place to a degree commensurate with the complexity and requirements of the project.

(1) A subsurface investigation shall be carried out to the depth and extent to which the building or excavation will significantly change the stress in the soil or rock, or to such a depth and extent as to provide all the necessary information for the design and construction of the excavation or the foundations.

(1) The identification and classification of soil, rock and groundwater and descriptions of their engineering and physical properties shall be in accordance with a widely accepted system.

(1) Except as permitted in Sentence (2), the bearing surface of a foundation shall be below the level of potential damage, including damage resulting from frost action, and the foundation shall be designed to prevent damage resulting from adfreezing and frost jacking.

(2) The bearing surface of a foundation need not be below the level of potential damage from frost where the foundation,

(a) is designed against frost action, or

(b) overlies material not susceptible to frost action.

(1) Where a foundation is to rest on, in or near sloping ground, this particular condition shall be provided for in the design.

(1) Where there is eccentricity or inclination of loading in foundation units, this effect shall be fully investigated and provided for in the design.

(1) Where dynamic loading conditions apply, the effects shall be assessed by a special investigation of these conditions and provided for in the design.

(1) Where a foundation or any part of a building is subject to hydrostatic uplift the effects shall be provided for in the design.

(1) Where proposed construction will result in a temporary or permanent change in the groundwater level, the effects of this change on adjacent buildings shall be fully investigated and provided for in the design.

(1) Where conditions of permafrost are encountered or proven to exist, the design of the foundation shall be based upon analysis of these conditions by a person especially qualified in that field of work.

(1) Where swelling or shrinking soils, in which movements resulting from moisture content changes may be sufficient to cause damage to a structure, are encountered or known to exist, such a condition shall be fully investigated and provided for in the design.

(1) Where rock that expands or deteriorates when subjected to unfavourable environmental conditions or to stress release is known to exist, this condition shall be fully investigated and provided for in the design.

(1) Buildings may be placed on fill if it can be shown by subsurface investigation that,

(a) the fill is or can be made capable of safely supporting the building,

(b) detrimental movement of the building or services leading to the building will not occur, and

(c) explosive gases can be controlled or do not exist.

(1) The structural design of the foundation of a building, the procedures and construction practices shall conform with the appropriate Sections of this Code unless otherwise specified in this Section.

(1) The design of excavations and of supports for the sides of excavations shall conform to the requirements of Subsection 4.2.4. and this Subsection.

(1) Every excavation shall be undertaken in such a manner as to prevent movement that would cause damage to adjacent buildings at all phases of construction.

(2) Material shall not be placed nor shall equipment be operated or placed in or adjacent to an excavation in a manner that may endanger the integrity of the excavation or its supports.

(1) The sides of an excavation in soil or rock shall be supported by a retaining structure conforming with the requirements of Articles 4.2.5.1. and 4.2.5.2., except as permitted in Article 4.2.5.4.

(1) The sides of an excavation in soil or rock may be unsupported where a design is prepared by a person especially qualified in this field of work in conformance with the requirements of Articles 4.2.5.1. and 4.2.5.2.

(1) Surface water, all groundwater, perched groundwater and in particular artesian groundwater shall be kept under control at all phases of excavation and construction.

(1) At all phases of excavation and construction, loss of ground due to water or any other cause shall be prevented.

(1) All sides of an excavation, supported and unsupported, shall be continuously maintained and protected from possible deterioration by construction activity or by the action of frost, rain and wind.

(1) Where an excavation is backfilled, the backfill shall be placed so as to,

(a) provide lateral support to the soil adjacent to the excavation, and

(b) prevent detrimental movements.

(2) The material used as backfill or fill supporting a footing, foundation or a floor on grade shall be of a type that is not subject to detrimental volume change with changes in moisture content and temperature.

(1) The design of shallow foundations shall be in conformance with the requirements of Subsection 4.2.4. and this Subsection.

(1) Where a shallow foundation is to be placed on soil or rock, the soil or rock shall be cleaned of loose and unsound material and shall be adequate to support the design load taking into account temperature, precipitation, construction activities and other factors that may lead to changes of the properties of soil or rock.

(1) Where a shallow foundation unit has not been placed or located as indicated on the drawings,

(a) the error shall be corrected, or

(b) the design of the foundation unit shall be recalculated for the altered conditions by the designer.

(1) Where a shallow foundation unit is damaged,

(a) it shall be repaired, or

(b) the design of the foundation unit shall be recalculated for the damaged condition by the designer.

(1) A deep foundation unit shall provide support for a building by transferring loads by end-bearing to a competent stratum at considerable depth below the structure, or by mobilizing resistance by adhesion or friction, or both, in the soil or rock in which it is placed.

(1) Deep foundation units shall be designed in conformance with Subsection 4.2.4. and this Subsection.

(2) Where deep foundation units are load tested, as required in Clause 4.2.4.1.(1)(c), the determination of the number and type of load test and the interpretation of the results shall be carried out by a person especially qualified in this field of work.

(3) The design of deep foundations shall be determined on the basis of geotechnical considerations taking into account,

(a) the method of installation,

(b) the degree of inspection,

(c) the spacing of foundation units and group effects,

(d) other requirements of this Subsection, and

(e) the appropriate structural requirements of Section 4.1. and Subsections 4.3.1., 4.3.3. and 4.3.4.

(4) The portion of a deep foundation unit permanently in contact with soil or rock shall be structurally designed as a laterally supported compression member.

(5) The portion of a deep foundation unit that is not permanently in contact with soil or rock shall be structurally designed as a laterally unsupported compression member.

(6) The structural design of prefabricated deep foundation units shall allow for all stresses resulting from driving, handling and testing.

(1) Permissible deviations from the design alignment and the location of the top of deep foundation units shall be determined by design analysis and shall be indicated on the drawings.

(1) Where a deep foundation unit has not been placed within the permissible deviations referred to in Article 4.2.7.3., the condition of the foundation shall be assessed by the designer.

(1) Deep foundation units shall be installed in such a manner as not to impair,

(a) the strength of the deep foundation units and the properties of the soil or rock on or in which they are placed beyond the calculated or anticipated limits,

(b) the integrity of previously installed deep foundation units, or

(c) the integrity of neighbouring buildings.

(1) Where inspection shows that a deep foundation unit is damaged or not consistent with design or good engineering practice,

(a) such a unit shall be reassessed by the designer, and

(b) any necessary changes shall be made and action taken as required.

(1) Where special foundation systems are used, such systems shall conform to Subsection 4.2.4. and Sentence 4.1.1.4.(2).

(1) Existing foundations may be used to support new or altered buildings provided they comply with all pertinent requirements of this Section.

(1) Buildings and their structural members made of wood shall conform to CAN/CSA-O86, “Engineering Design in Wood”.

(1) Glued-laminated members shall be fabricated in plants conforming to CAN/CSA-O177-M, “Qualification Code for Manufacturers of Structural Glued-Laminated Timber”.

(1) In areas known to be infested by termites, the requirements in Articles 9.3.2.9.v1v2, 9.12.1.1. and 9.15.5.1. shall apply.

(1) Buildings and their structural members made of plain and reinforced masonry shall conform to CSA S304.1, “Design of Masonry Structures”.

(1) Buildings and their structural members made of plain, reinforced or prestressed concrete shall conform to CSA A23.3, “Design of Concrete Structures”.

(1) Buildings and their structural members made of structural steel shall conform to CAN/CSA-S16, “Limit States Design of Steel Structures”.

(1) Buildings and their structural members made of cold formed steel shall conform to CAN/CSA-S136, “North American Specification for the Design of Cold-Formed Steel Structural Members”.

(1) Steel building systems shall be manufactured by companies certified in accordance with the requirements of CSA-A660, “Certification of Manufacturers of Steel Building Systems”.

(1) Buildings and their structural members made of aluminum shall conform to CAN3-S157, “Strength Design in Aluminum”, using the loads stipulated in Section 4.1., in accordance with limit states design in Subsection 4.1.3.

(1) Glass used in buildings shall be designed in conformance with CAN/CGSB-12.20-M, “Structural Design of Glass for Buildings”.

(1) The structural design of air-supported structures shall conform to CAN3-S367-M, “Air-Supported Structures” using the loads stipulated in Section 4.1., in accordance with limit states design in Subsection 4.1.3.

(1) Parking structures shall be designed in conformance with CAN/CSA-S413, “Parking Structures”.

(1) Every retaining wall that is designated in Sentence 1.1.1.1.(1) of Division A shall be protected by guards on all open sides where the public has access to open space at the top of the retaining wall.

(1) Where maintenance and window cleaning operations are intended to be carried out on the exterior of a building described in Article 1.3.2.2.v1 of Division A, anchor systems shall be provided where any portion of the roof is more than 8 m above adjacent ground level.

(2) Except as provided in Sentence (3), the anchor systems in Sentence (1) shall be designed, installed and tested in conformance with CSA Standard Z91, “ Safety Code for Window Cleaning Operations”.

(3) Other anchor systems may be used where such systems provide an equal level of safety.

(4) The anchor system material shall be made of stainless steel, or other corrosion resistant base material, or from steel that is hot dipped galvanised, in accordance with CAN/CSA-G164-M, “Hot Dip Galvanising of Irregularly Shaped Articles”.

(1) Except as provided in this Subsection, manure storage tanks shall comply with the requirements of the National Farm Building Code of Canada.

(2) Manure storage tanks shall be constructed of steel, reinforced concrete or prestressed concrete.

(3) Manure storage tank walls, bases and appurtenances, including piping for the conveyance of manure and associated connections and joints, shall be designed and constructed to prevent leakage of contents.

(4) Concrete for manure storage tanks shall,

(a) be manufactured from Type 50 cement,

(b) have a 28-day strength of at least 32 MPa, and

(c) have a water/cement materials ratio of not more than 0.45.

(5) Manure storage tanks shall be placed on undisturbed soil free of any organic, deleterious and extraneous materials and capable of supporting the superimposed design loads from the tanks.

(6) Where granular fills are used between the bases of manure storage tanks and the undisturbed soil, the granular fills shall be compacted to a Standard Proctor density of not less than 95 per cent.

O. Reg. 350/06, Division B, Part 4.