§ 27-639 Design.
AC § 27-639
The following design requirements shall supplement the applicable provisions of this subchapter.
(a)Flexibility. Suspenders, unless encased, may be considered as perfectly flexible.
(b)Elastic stretch. The elastic stretch of the suspenders shall be considered.
(c)Displacement. Displacement resulting from changes in magnitude and position of load and its affects on stress shall be considered.
(d)Other considerations. Consideration shall be given to the effects of temperature variations, partial and reversible wind loadings, and vibration.
(e)Allowable working load. The allowable working load in suspenders formed from bridge wire cable shall be computed on the basis of factors equal to one and one-half times dead load plus two and one-half times live load or one and two-tenths times dead load plus two times live load plus two times wind load, applied to the specified, minimum, ultimate strength of the suspender. The allowable working load in suspenders conforming to the materials specifications or several reference standards of this code shall be the allowable working stresses for tension members as prescribed in the applicable reference standard or, for those materials where allowable stresses for tension members are not prescribed, on factors of one and one-half times dead load plus two times live load or one and two-tenths times dead load plus one and one-half times live load, plus one and one-half times wind load, also applied to the specified minimum, ultimate strength of the suspender. In no case, however, shall the factor, applied to the yield strength of the material or to the prestretching or prestressing force, exceed one and one-tenth times dead load plus one and one-quarter times live load.
