| Each year, wind disasters in the United States cause billions of dollars of damage to buildings, most of which is to non-engineered buildings--especially homes. Winds appear to be one of the worst types of natural disasters in the nation, if not the worst.; It is often said that non-engineered buildings such as homes are more difficult to analyze than engineered buildings. This is due to the lack of information about the complex behavior of the connections used in non-engineered buildings and the lack of a methodology to analyze light-frame timber buildings which possess flexible joints.; This study was initiated to develop an analytical method to tackle the problem. A method is developed herein to analyze houses with non-rigid connections. The method used takes into account the diaphragm action of walls, floor, ceiling and roofs, and the flexibility of joints. The research also includes laboratory tests of flexible joints of typical wood-frame houses so that the joint characteristics can be understood and used for predicting the response of such houses. Different connectors were tested so that comparisons could be made of their behaviors. During testing, it was discovered that rotational stiffness of wood joints is a function of the axial load as well as the shear load. Axial tension reduced joint stiffness. It was also observed that for nail joints the critical load was usually reached at slip of less than 0.015". Comparison of nail joints to joints made of special connectors such as hurricane clips indicated that in general, connector joints out-performed nailed joints. It was also discovered that hole patterns on connectors played an important role on the strength of joints.; Numerical studies of a typical house using test data revealed that the flexible behavior of wood joints influences the final resultant forces by less than 2% while producing low moments approaching that of pinned joints. Numerical studies also revealed that although axial load can cause significant change in the values of joint stiffness, the final joint forces are changed by less than 1%.; A computer program was developed for the analysis of the forces and deflections of wood-frame houses, and a method was introduced for the identification of the weak-joints of the houses analyzed. |
