Research On Seismic Behavior And Strengthening Method Of Wood Frame With Masonry Infill Wall

Wooden structure is the main system in the traditional ancient architecture in China for thousnds of years, but there is so little perfectly preserved. Besides, the houses with load-bearing wood frame and masonry infill wall are yet widely used in rural places of Guangxi, Yunnan. At present, the number of the researches on the wood frame structure is growing, and those researches have got some achievements, but there is still very little research on wood frame with masonry infill wall.In view of this, based on the classical architectural book of Qing Dynasty, Engineering practice case, three specimens of wood frame with masonry infill walls were produced and tested under low cyclic loading to study seismic performance and strengthing methods. The first specimen was directly loaded, while the other two (one of them was pre-cracking) were tested after being strengthened, by the means of embedding steel bars into the horizontal masonry joints and bonding steel plates onto the masonry wall close to the wood columns. Based on the experimental investigation and theoretical analysis, some seismic performance indexes, such as failure characteristics, hysteresis curves, skeleton curves, load-carrying capacity, ductility and energy dissipation capacity, were obtained. Finally, experimental results showed that whether or not reinforced, the hysteresis curve presented like Z, and damage of the wood frame was mainly characterized by shear failure with significant shear slip, less energy dissipation capacity. But because of the envelope action by the wood frame, when the frame reached the ultimate load, the intensity did not decrease severely and the late ductility was large. The yield load of the second and third specimen increased 32.1% and 30.2%, while the peak load increased 27.8% and 20.6% relative to the first specimen. Although the second frame was pre-cracking with a horizontal crack whose width did not exceed 15mm, but after reinforced, it could be restored to its original strength.On the basis of the experiment, the author used finite element software of ABAQUS to build models of wood frame with masonry infill walls, and then discussed about the plane stress state under the horizontal force and the development trend of cracks in the wall. After analyzing factors, including aspect ratio, the average compressive strength of masonry, and the thickness of fill wall, it is not difficult to know the influence on load-displacement curve of wood frame of different factors. What’s more, based on the existing theories and experimental results, hysteretic model wood frame with masonry infill walls was established, and tri-stiffness formula was proposed comparing with the test results to provide the basis for future research on the seismic elastoplastic analysis.