磚造建築拱開口部水平返覆加載行為及補強方法實驗研究

本研究以實驗來探討磚造歷史建築中，拱開口牆體在水平返覆加載下之完整結構行為以及不同補強工法之效益。執行之試體共五道，試體尺寸均為239cm×203cm（寬×高），兩道（WU1、WU2）無補強之試體中，WU2另外施加垂直加載71.2kN，其他三道分別在牆體施作不同的補強工法。實驗過程採位移控制。實驗結果顯示無補強試體約在2／1000層間位移角時拱肩產生起始裂縫。另加軸壓之試體WU2，其起始開裂強度較WU1提升26%以上，極限加載則提昇14%以上。三種補強工法中，拱下緣嵌扁型不銹鋼之試體WS1在水平耐力提昇以及延緩中度破壞之發生，均較其他兩種工法顯著。綜合實驗結果，本文建議歷史建築結構評估時，針對拱開口磚牆，可以層間位移角2／1000做為起始破壞點，4／1000為性能極限點。在試體實驗之外，本文並以簡化模式推導拱開口牆體之水平耐力估算，此估算與試體極限加載相較，差值在6%以內。

關鍵字

歷史建築；砌體；磚拱；補強；層間位移角

並列摘要

In this study, the structural behavior and the effect of different strengthening method for historic masonry walls with arch openings under horizontally cyclic loading are investigated by experiment. There are five wall specimens manufactured in the size of 239cmx203cm (W×H). Two of which (WU1 and WU2) are un-strengthened. Specimen WU2 takes an additional vertical load of 71.2kN compared to WU1. For the other three strengthened specimens, different wall strengthening methods are employed. The experimental system is controlled by displacement. Results obtained from the two un-strengthened specimens show the initial crack occurred at a drift angle of approximately 2/1000. However, in specimen WU2 there is a 26% increase in initial crack strength, and a 14% increase in ultimate load, compared to specimen WU1. A comparison of the three strengthened specimens reveals that the method (of imbedding steel straps into arch intrados) used to strengthen specimen WS1 is the most effective in increasing the ultimate load as well as delaying the occurrence of medium damage. Based on the test results, we suggest that drift angle 2/1000 could be assigned as the initial damage point, and drift angle 4/1000 to be the ultimate performance point for historic building assessment. In this study, in addition to the specimen test, a method for evaluating the ultimate load of a brick wall with arch opening has been developed from a simplified model. Comparing the ultimate load evaluated and that obtained from test specimens, the difference is less than 6%.