Wind Load Sharing and Influence Coefficients for House Roof Structures

Residential house structures in Australia are timber-framed construction and their roof connections are the most vulnerable components to windstorms. The failure or partial failure of inter-component connections within the roofing system, creates a change in the load path and load transfer from roof to wall. A series of finite element models were developed to derive the vertical reaction influence coefficients of roof to wall connection (RWC) and load sharing of roof structural system. Hold-down forces of RWCs were derived by using vertical reaction influence coefficient and wind tunnel model test data. The results show when the single rafter RWCs failed in the roof, the hold-down forces of adjacent rater’ RWCs will increased by about 55%. Overall outcomes of this research are being used as part of the BNHZ-CRC projects for retrofitting the roof structure and to develop vulnerability models for the houses.