基于实际震害和数值分析的加固建筑结构抗震性能研究

在地震多发国家和地区,很多老建筑或抗震能力达不到现行规范要求的建筑均面临抗震性能评估和加固问题.加固方法种类繁多,各种加固方案的结构抗震性能具有较大的不确定性.介绍了汶川地震中汉旺镇一栋仅遭受轻微结构损伤的老式无筋砌体结构的加固方法,分析了其表现良好的原因;并就1985年墨西哥城大地震中一栋加固建筑表现出的良好抗震性能进行了分析.以都江堰某需抗震加固的实际工程为例,用ANSYS分别对加固前原结构、加大截面法实施加固后的结构以及增设钢支撑加固后的结构进行了3维非线性动力时程分析.综合分析数值计算结果和经受地震考验的成功加固案例后认为,对原结构深入的抗震性能评估是选择加固方案的前提;结构抗震加固应强调对结构整体抗震性能的优化,而不是结构构件简单的修复;加固方案应尽量避免增加结构的自重,优先选择相对轻质高强材料;侧向刚度的增大可能导致地震反应显著增加,故增大侧向刚度并不一定能有效降低结构的水平侧移,建议加固后结构强度提高的程度应高于刚度增加的程度;应允分认识到加固可能带来新的薄弱环节和新的不利受力状态.

Seismic performance of strengthened buildings tested by earthquake and analyzed by numerical simulation

Seismic assessment and strengthening of existing old, under-designed buildings for seismic forces is a subject that has received a lot of attention from civil engineers and researchers in many areas of high seismicity around the world. Existing buildings with various strengthening systems have quite different seismic performances from one to another. A summary of the damage and retrofitting of an unreinforced masonry structure in Hanwang town which suffered slight damage during Wenchuan Earthquake was presented, and the role of the strengthening system was evaluated. A seismic retrofitting building which had excellent performance during 1985 Mexico Earthquake was also assessed. Numerical simulation on seismic retrofitting performance of one building located in Dujiangyan was conducted based on ANSYS. Comparison of analysis results and the two case buildings shows that: seismic assessment of existing building is crucial to choose the retrofitting system; global seismic performance of one building should be optimized after being retrofitted and not but simple repair; less increase of the weight of one retrofitted building is an important factor in success of retrofit solution; some retrofitting solutions may lead to higher increase in weight which would lead to reduce the efficiency of the stiffening, and lead to higher seismic roads; and large earthquake force may be developed due to retrofitting systems.