既有钢筋混凝土框架抗剪能力分析

Shear resistance of an existing reinforced concrete frame

为研究既有结构地震损伤直至破坏的特点,选取1栋20世纪80年代初建造的钢筋混凝土框架结构的一榀单跨平面框架进行Pushover分析。基于OpenSees分析平台,得出结构破坏过程中塑性铰截面处的剪力需求,并与现行规范中的截面抗剪能力进行比较。研究结果表明:结构在出现塑性铰的过程中,将出现脆性剪切破坏;结构的破坏机理是底层柱发生弯曲-剪切破坏。建议对既有建筑结构进行抗震评估时,必须考虑梁、柱剪切破坏模式。该方法可用于结构抗剪能力及延性的初步评估。

Pushover analysis was performed to study the seismic damage and failure pattern of aged existing building structures during earthquake. The target structure was a single-span,single-bay reinforced concrete frame built in early 80＇s of the 20th centenary. By using OpenSees software,the shear demand at plastic hinges of the damaged structure was obtained and compared with the shear capacity in the current design code. The results show that the brittle shear failure may occur at some plastic hinges,and that final breakdown of the structure is caused by the shear-bending failure occurring at the first story columns. The structural displacement limit for shear resistance is also proposed. The shear failure model of beam and column should be taken into account for seismic assessment of existing aged building structures. The proposed method is applicable to preliminary evaluation of structural shear capacity and ductility.