Study On The Seismic Performance Of Light Wood-framed House

Light wood-framed house is a new structural system in China, there are manyresearch works need to do in this field. This thesis focus on the first shake tabletests on light wood-framed house in China. The performances of nailed connection,shear walls and wood house were studied through numerical modeling andexperimental verification. The study emphases, method and conclusions of theinvestigation were listed as following.1. The load-slip curves of nail connection in monotonic and cyclic testsindicated the character of high nonlinear, pinched, strength degradation andstiffness degradation. Foschi exponential curve and Johnn Q-pinch hysteresismodel were used to model nail connections and showed enough precision.2. Six shear walls tests were respectively conducted under monotonic and cyclicloads and the effect of vertical loads, transverse walls, hold-downs and openings onthe performance of shear walls were studied. The results showed that the vertical loadcan dramatically improve the structural performances of shear walls, while thetransverse walls could improve the capacity of shear walls slightly. Different openingsizes have a direct impact on the ultimate displacement and energy dissipation ofthe shear walls.3. The oriented spring pair and several types of hysteresis rule were included inJohnn's user-defined element, which could model the many features of nailconnection. ABAQUS and the above user defined element were used to simulateshear walls, and the load-displacement curve resulting from modeling agreed wellwith the tests response. A new method to model frame nail connections was proposedin this thesis to analyze the shear walls with stud uplift under lateral loads.4. The specimen for shake table tests is a full size two-storey lightwood-framed house. Different opening size, earthquake input, shake direction andasymmetrical configurations were considered in the tests. The whole shake table testsincluded five phases, four model status and 67 single tests. The test results showedthat the specimen performed elastic and had no visual damage during 0.2g PGA tests. In the tests of 0.2g to 0.4g, the tested structures showed nonlinear and were damagedslightly. The tested symmetric building with progressively lager opening couldwithstand successive application of three different seismic ground motions in theorder of 0.55g PGA without collapse. Interstory drifts in the first story were generallybellow 1/500, 1/250 and 1/80 at nominal levels of 0.1g, 0.2g and 0.4g peak tableaccelerations. For the asymmetrical building, the responses of acceleration anddisplacement of specimen were generally larger than that of symmetrical building.The light wood-framed house specimen can meet the requirement for seismicintensity 8 described in China Seismic Design Code (GB 50011-2001).5. A three dimension house model was established in Drain 3D with a userdefined nonlinear spring element. Nonlinear time-history analysis of shake table testsmodel was carried out in Drain 3D with this three dimension model. The result ofanalysis was in fair agreement with tests response and this model can be used toanalyze more sophisticated structure in the future. The selection of the parameter ofnonlinear spring in shear wall model is the first key step in this analysis and theirmethods were also described in this thesis. Parameter studies such as gypsum board,cumulate damage, damping ratio, and the stiffness of floor were also carried out usingthis three dimension model.