Experimental structural behavior of wall-diaphragm connections for older masonry buildings

Wall-diaphragm connections can affect overall seismic performance of older unreinforced masonry buildings, but there is little test data available about the structural behavior of such connections. Results are presented of an experimental study designed to evaluate the behavior of typical brick wall to wood joist/diaphragm connections. Tests were conducted on two different types of component specimens (with and without nailed strap anchors), using three different loading methods (static monotonic, as well as static and dynamic cyclic). Contributions of friction (activated at brick joist supports to represent gravity load normal force effects) and of strap anchor nails loaded in shear have been considered separately and together in the testing matrix. Force vs. displacement envelope and hysteresis curves have been developed from the experimental data. Also from these data, simplified average multi-linear plots derived from all the experiments can be compared based on different test specimen and loading types, leading to aggregate findings about various distinctive structural behaviors exhibited. These findings include typical strengths and failure modes, as well as stiffness and/or friction coefficient values as a function of displacement, for all the test specimens. Results obtained from these masonry connection tests can be used in numerical analyses of whole building systems.