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: Vp = Ssed IE (Cp Ar ⁄R p )Wp where Ssed = peak spectral acceleration, Sa(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 IE, Cp, Ar, Rp, Wp = 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 IES(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 Ar = 1.0, Ax = 3.0, Cp = 1.0, and Rp = 1.25, (f) the minimum clearance between the array and other arrays or fixed objects is the greater of (i) 225 mm, and (ii) 1 500(IES(0.2) − 0.4) , 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(IES(0.2) − 0.4) , 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))