鋼筋混凝土構架內含填充磚牆之耐震補強研究

Abstract

由歷年勘災經驗顯示，有不少的鋼筋混凝土建築物嚴重受損、倒塌，並造成重大之損失。倒塌之建築物大多都因為柱之垂直承載力喪失所致，並從中發現大多為非韌性配筋，即其箍筋間距過大或不具備135度耐震彎鉤而是90度彎鉤，而使得這些柱可能無法具備良好的消能與變形能力。 本研究進行了五座鋼筋混凝土構架內含填充磚牆試體，一共設計了兩種補強方式，以碳纖維貼片、預力鋼棒提供拉桿力來模擬中間柱之束制。除了預力鋼棒補強試體外，其於皆分別以先砌式及後砌式構法製作。並觀察試體之面內側向強度與破壞路徑之相關性，以及分析模型之評估。 實驗結果顯示，填充磚牆的面內側向強度的確與磚牆的破壞路徑有關，亦即與磚牆的高長比有關。而無論哪種補強方式，皆能有效改變其破壞路徑及提升側向強度。若補強在相同拉桿力之條件下，施加預拉力的半主動控制補強會比貼覆CFRP的被動控制補強的效益佳，因為CFRP一旦與牆體脫開，則不再具有補強效果，而預力鋼棒之效益卻可直至試驗結束。。 在分析方面，本研究係將目前TEASPA既有之側力位移曲線預測方法與試驗結果進行比對，以確認各方法在本研究試體之適用性。結果顯示分析曲線，已能接近試驗結果。 藉由本研究之試驗結果，以供工程師於未來設計鋼筋混凝土構架內含填充磚牆時，能將高長比納為主要設計參數。

The observation of seismic reconnaissance showed that the old reinforced concrete buildings in Taiwan were severely damaged, and there were thousands of casualties and a great loss of property. Majority of building collapse resulted from the loss of vertical-load carrying capacities of columns. Most of the damaged columns were found with non-ductile detailing, such as widely spaced hoops with 90 degree hooks. Such columns are known to have poor seismic performance in terms of ductility and energy dissipation capacity. Five reinforced concrete frames with brick infills were tested to investigate the influence of the lateral strength of brick infill related to the major fracture path and the height-to-length ratio. Therefore, two seismic retrofitting methods including the carbon fiber reinforced plastic sheets and the pre-tensioned rods were designed to simulate the effects of intermediate columns. Except for the specimen of the pre-tensioned rods, the other parameter was the types of construction pre-lay masonry and post-lay masonry. The test results indicated that the lateral strength of brick infills strongly related to the major fracture path and the height-to-length ratio. Both retrofitting measures can effectively transform the fracture path and raise the lateral strength of brick infills. Under the same conditions, the semi-active control retrofitting of the pre-tensioned rods is better than the passive control of the carbon fiber reinforced plastic sheets. If the carbon fiber reinforced plastic delamination occurs, it no longer has the retrofitting effect of the brick wall. However, the effectiveness of the retrofitting of the pre-tensioned rods can be sustained longer. The experimentally observed strength was compared with the predicted values based on the TEASPA analytical models to confirm the applicability of the each method in this study. Based on the results of this study, it is recommended that height-to-length ratio should be adopted as a design parameter in seismic design of reinforced concrete frames with brick infills.