Behavior of traditional timber frame structures subjected to lateral load.

摘要

Timber framing is a method of construction where wood columns and beams are connected with wood pegs. Timber frames may be enclosed in a variety of manners, but the most common enclosure system is the structural insulated panel (SIP). Current building codes do not provide guidelines for wood structures with wood pegged connections, and the intent of this research project was to provide a basis for implementation of this type of structure into the building codes.; Specifically, this project investigated the effects of lateral load on the stiffness of full-scale timber frames. Lateral load was applied to one-story one-bay (1S1B) and two-story two-bay (2S2B) frames of various species. The frames were tested in both the unsheathed and sheathed condition and were modeled with a structural analysis program. Single-fastener SIP-to-timber connections were tested to quantify the load-slip characteristics of such joints.; Excessive displacements of the frames indicated unacceptable flexibility when subjected to reversible lateral loads. This lack of stiffness was due to the inefficiency of knee braces for resisting lateral load. However, as exhibited by a difficulty to catastrophically fail a frame, the knee brace system provided exceptional strength characteristics due to the substantial available compressive action of the joints. The addition of SIP sheathing significantly improved frame stiffness. Internal actions in the statically determinate 1S1B frame were demonstrated to be independent of connection properties, but in the indeterminate 2S2B frame, internal actions were a function of connection stiffness.; The stiffness of a wood-pegged timber frame is highly dependent on the stiffness of the individual pegged connections, and in order to accurately model the displacement characteristics of a frame, the characteristics of the connections must be included in the model. Implementation of nonlinear springs to model pegged joints subjected to tensile loads provided some improvement in overall model accuracy, but the use of nonlinear springs at compressive joints is not recommended. For sheathed frame models, the implementation of nonlinear SIP to timber connection elements produced accurate predictions of sheathed frame stiffness.