A Study of Load-Displacement Relationship For Masonry Wall and Seismic Assessment Application

• Main Authors: To-NanChen, 陳拓男
• Other Authors: Ja-shian Chang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/11180172402157964573

博士 === 國立成功大學 === 建築學系碩博士班 === 98 === In Taiwan, the wall element is the most important part that provides the earthquake resistance for the historic building. Thus during conservation design, the completed behavior of the wall element under earthquake need to be available and uses it to assess the resistant capacity of the structure and retrofit the weak wall. In this paper , the compressive truss model theory has be adopted to calculate the P-△ curve of URM wall , and the softening of principal compressive stress was counted in the calculation. Considering the wall that need to be retrofitted , the strengthen method that retrofitting with wire mesh in the inside surface of the wall has been adopted , due to its advantages of economic and not changing the architectural scenery. For establishing the calculation process of the P-△ curve , it assumed that the strengthening effect is contributed by wire mesh and the mortar that enclose wire mesh. The contribution of wire mesh is based on the concept of shear friction. The additional compressive stress of the brick wall due to the wire yield stress was also counted in the calculation of wall displacement. For explaining the seismic assessment application of the P-△ curve , three historic buildings are chosen to run the seismic assessment. The main results obtained in this study are as following: (1) For URM wall , the calculated curves considering the softened effect obtain good agreement with the test results. This result shows the softening of principal compressive stress due to the principal tensile strain should not be ignored when using the compressive truss model to analyze the masonry shear wall. (2) The calculated curves used for the URM walls with lower vertical dead load show good agreement with the test results. Due to the historical masonry buildings in Taiwan mostly have one or two floors , and the vertical dead load acting on the wall is belong to lower vertical loading , it can adopt the assessing method established in this study to calculate the P-△ curves of the wall. (3) For strengthening method that retrofitting URM wall with wire mesh，the strengthening effect is mainly contributed by the wire mesh, and increasing the cross-section of the wire in unit width of the wall will more effectively improve the performance of the wall than increasing the strength of the plastered mortar. (4) For the brick wall strengthened with wire mesh , according to the comparison of calculation and five brick specimens , the calculated P-△ curves obtain a good agreement with the test results and the ultimate loading and displacement of the brick wall under in-plane loading can be obtained reasonably. (5) In practical usage , the P-△ curve calculated by using the formula established in this study can effectively assess the in-plane safe index of the wall and whether the seismic performance reach the legal standard. Besides , it also can use to assess the out-of-plane safe of the wall which is perpendicular to the assess in-plane wall.