Load Distribution in Timber Structures Consisting of Multiple Lateral Load Resisting Elements with Different Stiffnesses

Abstract

It is well known that the stiffness properties of diaphragms and lateral load resisting elements (LLREs) influence the load distribution between LLREs under lateral load induced by earthquake or wind. Where a more sophisticated method of calculating the load distribution in a lateral load resisting system is used, often it is based on the concept of a beam on an elastic foundation. This approach could be tedious to apply in design when there are more than a few LLREs. A multiple-spring model (MSM), whereby the translational springs are used to model the diaphragm stiffnesses and the stiffnesses of the LLREs, is proposed. The model was validated with test and finite-element results of a particular benchmark building. The lateral load distribution between LLREs with various stiffness ratios of diaphragm to LLRE was also investigated. The results show that, contrary to common belief, the forces transferred by a semirigid diaphragm to supporting LLREs may be higher than those predicted by flexible and rigid-diaphragm assumptions. Therefore, using the envelope force approach may lead to underestimation of the design forces in the shear walls.