Earthquake load and effects (4.1.8)

(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 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. (See Note A-4.1.8.3.(4))

(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 precast 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. (See Note A-4.1.8.3.(6))

(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 (See Note A-4.1.8.3.(7)(b) and

(c)

(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. (See Note A-4.1.8.3.(7)(b) and (c))

(8)Structural modeling 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.

(See Note A-4.1.8.3.(8))

(1)Except as provided in Articles 4.1.8.20. and 4.1.8.22., 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 value 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 rooftop structures not exceeding two storeys in height whose weight is less than the greater of 10% of W and 30% of W_i 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.(6) must be satisfied. (See Note A-4.1.8.9.(4))

(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 defined 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. (See Note A-4.1.8.9.(5))

(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., are not permitted unless the Seismic Category is SC1 and the forces used for design of the SFRS are multiplied by R_dR_o .

(2)Post-disaster buildings shall

(a)not have Type 1, 3, 4, 5, 7, 9 or 10 irregularities as described in Table 4.1.8.6., where the Seismic Category is SC3 or SC4.

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

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

(d)where they are constructed with concrete or masonry shear walls, have no storey with a lateral stiffness that is less than that of the storey above it, and

(e)where they are constructed with other types of SFRS, have no storey for which the interstorey deflection under lateral earthquake forces divided by the interstorey height, h_s, is greater than that of the storey above it.

(3)High Importance Category buildings shall

(a)not have Type 1, 3, 4, 5, 7, 9 or 10 irregularities as described in Table 4.1.8.6., where the Seismic Category is SC4,

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

(c)have an SFRS with an R_d of at least

(i)2.0 where the Seismic Category is SC4, and

(ii)1.5 otherwise,

(d)where they are constructed with concrete or masonry shear walls, have no storey with a lateral stiffness that is less than that of the storey above it, and

(e)where they are constructed with other types of SFRS, have no storey for which the interstorey deflection under lateral earthquake forces divided by the interstorey height, h_s, is greater than that of the storey above it.

(4)Where the fundamental lateral period, T_a , is greater than or equal to 1.0 s and I_ES(1.0) is greater than 0.25, shear walls that are other than wood-based and form part of the SFRS shall be continuous from their top to the foundation and shall not have Type 4 or 5 irregularities as described in Table 4.1.8.6.

(5)For buildings in Seismic Category SC3 or SC4 that are constructed with more than 4 storeys of continuous wood construction, timber SFRSs consisting of shear walls with wood-based panels or of braced or moment-resisting frames as defined in Table 4.1.8.9. within the continuous wood construction shall not have Type 4 or 5 irregularities as described in Table 4.1.8.6. (See Note A-4.1.8.10.(5) and (6))

(6)For buildings in Seismic Category SC3 or SC4 that are constructed with more than 4 storeys of continuous wood construction, timber SFRSs consisting of moderately ductile or limited ductility cross-laminated timber shear walls, platform-type construction, as defined in Table 4.1.8.9. within the continuous wood construction shall not have Type 4, 5, 6, 8, 9 or 10 irregularities as described in Table 4.1.8.6. (See Note A-4.1.8.10.(5) and (6))

(7)The ratio α for a Type 9 irregularity as described in Table 4.1.8.6. shall be determined independently for each orthogonal direction using the following equation:

α = Q_G/Q_y

where

Q_G = gravity-induced lateral demand on the SFRS at the critical level of the yielding system, and

Q_y = the resistance of the yielding mechanism required to resist the earthquake loads, which need not be taken as less than R_o multiplied by the specified lateral earthquake force as determined in Article 4.1.8.11. or 4.1.8.12., as appropriate.

(See Note A-4.1.8.10.(7))

(8)For buildings with a Type 9 irregularity as described in Table 4.1.8.6. and where I_ES(0.2) is equal to or greater than 0.5, deflections determined in accordance with Article 4.1.8.13. shall be multiplied by 1.2.

(9)For buildings where the value of α , as determined in accordance with Sentence (7), exceeds twice the appropriate limit specified in Table 4.1.8.6. for a Type 9 irregularity and where I_ES(0.2) is equal to or greater than 0.5, a Non-linear Dynamic Analysis of the structure shall be carried out in accordance with Article 4.1.8.12. and the following criteria:

(a)the analysis shall account for the effects of the vertical response of the building mass,

(b)the analysis shall account for the effects of the vertical response of building components that undergo a vertical displacement when displaced laterally,

(c)the analysis shall use vertical ground motion time histories that are compatible with horizontal ground motion time histories scaled to the target response spectrum and that are applied concurrently with the horizontal ground motion time histories.

(d)the largest interstorey deflection at any level of the building as determined from the analysis shall not be greater than 60% of the appropriate limit stated in Sentence 4.1.8.13.(3), and

(e)the results of an analysis using the ground motion time histories in Clause (c) multiplied by 1.5 shall satisfy the non-linear acceptance criteria. (See Note A-4.1.8.10.(9))

(10)The design of buildings in Seismic Category SC3 or SC4 with a Type 10 irregularity as described in Table 4.1.8.6. shall satisfy the following requirements:

(a)the structure shall be designed to resist the additional earthquake forces due to the vertical accelerations of the mass supported by inclined vertical members, and (See Note A-4.1.8.10.(10)(a))

(b)the effects of the horizontal and vertical movements of inclined vertical members, while undergoing earthquakeinduced deformations, on the floor systems they support shall be considered in the design of the building and accounted for in the application of Sentence 4.1.8.3.(5).

(1)Analysis for earthquake actions shall be carried out in accordance with the Dynamic Analysis Procedure described in Article 4.1.8.12. (See Note A-4.1.8.7.(1)), except that the Equivalent Static Force Procedure described in Article 4.1.8.11. may be used for structures that meet any of the following criteria:

(a)where the Seismic Category is SC1 or SC2,

(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 a structural irregularity of Type 2, 3, 4, 5, 6 or 8 as defined in Table 4.1.8.6. 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)The static loading due to earthquake motion shall be determined according to the procedures given in this Article.

(2)Except as provided in Sentence (12), the specified lateral earthquake force, V, shall be calculated using the following formula:

V = S(T_a)M_vI_EW/(R_dR_o)

except,

(a)for walls, coupled walls and wall-frame systems, V shall not be less than,

S(4.0)M_vI_EW/(R_dR_o)

(b)for moment-resisting frames, braced frames and other systems, V shall not be less than,

S(2.0)M_vI_EW/(R_dR_o)

, and

(c)for buildings located on a site designated as other than X_F and having an SFRS with an R_d equal to or greater than 1.5, V need not be greater than the larger of

(2/3)S(0.2)I_EW/(R_dR_o)

, and

S(0.5)I_EW/(R_dR_o)

(3)Except as provided in Sentence (4), 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 lateral earthquake 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)0.1N for other moment frames,

(b)0.025 h_n for braced frames,

(c)0.05(h_n)^(3/4) for shear wall and other structures, 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 as greater than 1.5 times that determined in Clause (a),

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

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

(iv)for other structures, Ta shall not be taken as greater than that determined in Clause (c), and

(v)for the purpose of calculating the deflections, the period without the upper limit specified in Subclauses (d)(i) to (d)(iv) may be used, except that, for walls, coupled walls and wall-frame systems, T_a shall not exceed 4.0 s, and for moment-resisting frames, braced frames, and other systems, T_a shall not exceed 2.0 s. (See Note A-4.1.8.11.(3))

(4)For single-storey buildings with steel deck or wood roof diaphragms, the fundamental lateral period, T_a , in the direction under consideration is permitted to be taken as,

(a)0.05(h_n)^(3/4) + 0.004L for shear walls,

(b)0.035h_n + 0.004L for steel moment frames and steel braced frames, or

(c)the value obtained from methods of mechanics using a structural model that complies with the requirements of Sentence 4.1.8.3.(8), except that Ta shall not be greater than 1.5 times the value determined in Clause (a) or (b), as applicable,

where L is the shortest length of the diaphragm, in m, between adjacent vertical elements of the SFRS in the direction perpendicular to the direction under consideration.

(5)The weight, W, of the building shall be calculated using the following formula:

W = ∑_(i = 1)^nW_i

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

(7)The specified lateral earthquake force, V, shall be distributed such that

(a)a portion, F_t, is concentrated at the top of the building, where F_t is equal to 0.07T_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, and

(b)the remainder, V - F_t , is distributed along the height of the building, including the top level, in accordance with the following formula:

F_x = (V - F_t)W_xh_x/(∑_(i = 1)^nW_ih_i)

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

M_x = J_x∑_(i = x)^nF_i (h_i - h_x)

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.

(9)Torsional effects that are concurrent with the effects of the forces determined in Sentence (7) and are caused by the simultaneous actions of the following torsional moments shall be considered in the design of the structure according to Sentence (11):

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

(b)torsional moments due to accidental eccentricities.

(10)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 forces determined in Sentence (7) 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 forces determined in Sentence (7).

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

(a)for a building with B ≤ 1.7 or in Seismic Category SC1 or SC2, 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 + 0.10D_nx) , and

(ii)T_x = F_x(e_x − 0.10D_nx)

(b)for a building with B > 1.7 in Seismic Category SC3 or SC4, by a Dynamic Analysis Procedure as specified in Article 4.1.8.12.

where F_x is determined in accordance with Sentence (7) and where each element of the building is designed for the most severe effect of the above load cases.

(12)Where the fundamental lateral period, T_a, is determined in accordance with Clause (3)(d) and the building is constructed with more than 4 storeys of continuous wood construction and has a timber SFRS consisting of shear walls with wood-based panels or of braced or moment-resisting frames as defined in Table 4.1.8.9., the specified lateral earthquake force, V, as determined in Sentence (2) shall be multiplied by 1.2 but need not exceed the value determined by using Clause (2)(c). (See Note A-4.1.8.10.(5) and (6))

(1)Except as provided in Sentences (5) and (6), 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. and 4.1.8.12. and incorporating the effects of torsion, including accidental torsional moments, shall be multiplied by R_dR_o/I_E and increased as required in Sentences 4.1.8.10.(8) and 4.1.8.16.(1) to give realistic values of anticipated deflections.

(3)Based on the lateral deflections calculated in Sentences (2), (5) and (6), the largest interstorey deflection at any level shall be limited to 0.01 h_s for post-disaster buildings, 0.02 h_s for High Importance Category buildings, 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.(12). (See Note A-4.1.8.13.(4))

(5)The lateral deflections of a seismically isolated structure shall be calculated in accordance with Article 4.1.8.20.

(6)The lateral deflections of a structure with supplemental energy dissipation shall be calculated in accordance with Article 4.1.8.22.

(1)Except as provided in Sentences (2), (7) and (16), elements and components of buildings described in Table 4.1.8.18. 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 (9), and shall be designed for a specified lateral earthquake force, V_p , distributed according to the distribution of mass:

V_rmp = 0.3S(0.2)I_rmES_rmpW_rmp

where

S(0.2) = design spectral acceleration value at a period of 0.2 s, as defined in Sentence 4.1.8.4.(6),

I_E = earthquake 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 as 0.7), where

C_p = element or component factor from Table 4.1.8.18.,

A_r = element or component force amplification factor from Table 4.1.8.18.,

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

R_p = element or component response modification factor from Table 4.1.8.18., and

W_p = weight of the component or element.

(2)For buildings in Seismic Category SC1 or SC2, other than post-disaster buildings, seismically isolated buildings, and buildings with supplemental energy dissipation systems, the requirements of Sentence (1) need not apply to Categories 6 through 22 of Table 4.1.8.18.

(3)For the purpose of applying Sentence (1) for Categories 11 and 12 of Table 4.1.8.18., 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 and rigidly connected.

(4)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.

(5)When the mass of a tank plus its contents or the mass of a flexible or flexibly connected piece of machinery, fixture or equipment is greater than 10% of the mass of the supporting floor, the lateral forces shall be determined by rational analysis.

(6)Forces shall be applied in the horizontal direction that results in the most critical loading for design, except for Category 6 of Table 4.1.8.18., where the forces shall be applied up and down vertically.

(7)Connections to the structure of elements and components listed in Table 4.1.8.18. 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)except as provided in Sentence (17), friction due to gravity loads shall not be considered to provide resistance to earthquake 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 shallow post-installed mechanical, post-installed adhesive, and cast-in-place anchors in concrete shall be 1.5, where shallow anchors are those with a ratio of embedment length to diameter of less than 8,

(d)post-installed mechanical, drop-in and adhesive anchors in concrete shall be pre-qualified for seismic applications by cyclic load testing in accordance with

(i)CSA A23.3, "Design of concrete structures," and

(ii)ACI 355.2, "Qualification of Post-Installed Mechanical Anchors in Concrete (ACI 355.2-19) and Commentary," or ACI 355.4, "Qualification of Post-Installed Adhesive Anchors in Concrete (ACI 355.4-19) and Commentary," as applicable,

(e)post-installed mechanical and adhesive anchors in masonry and post-installed mechanical anchors in structural steel shall be pre-qualified for seismic applications by cyclic tension load testing, (See Note A-4.1.8.18.(7)(e))

(f)power-actuated fasteners shall not be used for cyclic tension loads,

(g)connections for non-structural elements or components of Category 1, 2 or 3 of Table 4.1.8.18. attached to the side of a building and above the first level above grade shall satisfy the following requirements:

(h)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 4.1.8.18., and all of the other parts of the connection, such as anchors, welds, bolts and inserts, shall be capable of developing 2.0 times the nominal yield resistance of the body of the connection, and

(i)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 4.1.8.18., and

(j)a ductile connection is one where the body of the connection is capable of dissipating energy through cyclic inelastic behaviour.

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

(9)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.

(10)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).

(11)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.

(12)Isolated suspended equipment and components, such as pendent lights, may be 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 (10) are satisfied.

(13)Free-standing steel pallet storage racks are permitted to be designed to resist earthquake effects using rational analysis, provided the design achieves the minimum performance level required by Subsection 4.1.8. (See Note A-4.1.8.18.(13) and 4.4.3.1.(1).)

(14)Except as provided in Sentence (15), the relative displacement of glass in glazing systems, D_fallout , shall be equal to the greater of

(a)D_fallout ≥ 1.25I_ED_p , where

D_fallout = relative displacement at which glass fallout occurs, and

D_p = relative earthquake displacement that the component must be designed to accommodate, calculated in accordance with Article 4.1.8.13. and applied over the height of the glass component, or

(b)13 mm.

(See Note A-4.1.8.18.(14) and (15))

(15)Glass need not comply with Sentence (14), provided at least one of the following conditions is met:

(a)the Seismic Category is SC1 or SC2,

(b)the glass has sufficient clearance from its frame such that D_clear ≥ 1.25D_p calculated as follows:

D_clear = 2C_1(1 + h_pC_2/(b_pC_1))

where

D_clear = relative horizontal displacement measured over the height of the glass panel, which causes initial glass-to-frame contact,

C₁ = average of the clearances on both sides between the vertical glass edges and the frame,

h_p = height of the rectangular glass panel,

C_2 = averages of the top and bottom clearances between the horizontal glass edges and the frame, and

b_p = width of the rectangular glass panel,

(c)the glass is fully tempered, monolithic, installed in a non-post-disaster building, and no part of the glass is located more than 3 m above a walking surface, or

(d)the glass is annealed or heat-strengthened laminated glass in a single thickness with an interlayer no less than 0.76 mm and captured mechanically in a wall system glazing pocket with the perimeter secured to the frame by a wet, glazed, gunable, curing, elastomeric sealant perimeter bead of 13 mm minimum glass contact width.

(See Note A-4.1.8.18.(14) and (15))

(16)For structures with supplemental energy dissipation, elements and components of buildings described in Table 4.1.8.18. and their connections to the structure shall be designed for a specified lateral earthquake force, V_p , determined at each floor level as follows:

V_p = S_sedI_E(C_pA_r/R_p)W_p

where

S_sed = peak spectral acceleration, S_a(T,X) , in the period range of T=0 s to T=0.5 s determined from the mean 5%-damped floor spectral acceleration values by averaging the individual 5%-damped floor response spectra at the centroid of the floor area at that floor level determined using Non-linear Dynamic Analysis, and

I_E,C_p,A_r,R_p,W_p = as defined in Sentence (1).

(See Note A-4.1.8.18.(16))

(17)For a ballasted array of interconnected solar panels mounted on a roof, where I_ES(0.2) is less than or equal to 1.0, friction due to gravity loads is permitted to be considered to provide resistance to seismic forces, provided

(a)the roof is not normally occupied,

(b)the roof is surrounded by a parapet extending from the roof surface to not less than the greater of

(i)150 mm above the centre of mass of the array, and

(ii)400 mm above the roof surface,

(c)the height of the centre of mass of the array above the roof surface is less than the lesser of

(i)900 mm, and

(ii)one half of the smallest plan dimension of the supporting base of the array,

(d)the roof slope at the location of the array is less than or equal to 3°,

(e)the factored friction resistance calculated using the kinetic friction coefficient determined in accordance with Sentence (18) and a resistance factor of 0.7 is greater than or equal to the specified lateral earthquake force, V_p , on the array determined in accordance with Sentence (1) using values of A_r = 1.0 , A_x = 3.0 , C_p = 1.0 , and R_p = 1.25 ,

(f)the minimum clearance between the array and other arrays or fixed objects is the greater of

(i)225 mm, and

(ii)1500(I_ES(0.2) - 0.4)2 , in mm, and

(g)the minimum clearance between the array and the roof parapet is the greater of

(i)450 mm, and

(ii)3 000(I_ES(0.2) - 0.4)^2 , in mm.

(18)For the purpose of Clause (17)(e), the kinetic friction coefficient shall be determined in accordance with ASTM G115, "Standard Guide for Measuring and Reporting Friction Coefficients," through experimental testing that

(a)is carried out by an accredited laboratory on a full-scale array or a prototype of the array,

(b)models the interface between the supporting base of the array and the roof surface, and

(c)accounts for the adverse effects of anticipated climatic conditions on the friction resistance.

(See Note A-4.1.8.18.(18))