圈梁-构造柱约束砖砌体房屋的抗地震倒塌性能分析

2008年5.12汶川大地震的经验显示,在遭受远超过抗震设防烈度的强烈地震下,砖砌体房屋结构既要具备一定的抗地震倒塌能力,又应在最后倒塌无法避免时能够在倒塌的时间顺序和空间上体现出合理性,即实现所谓的合理倒塌模式,才能最大限度地保障人民生命财产安全。通过引入等效受压斜撑宏观模型,分析并建立了圈梁-构造柱与砖墙体之间的传力路径以及相互作用,探讨约束砖墙体在平面内地震作用下的两种倒塌机制及其计算方法,提出反映圈梁-构造柱对砖墙约束能力的约束因子和反映砖墙抗地震倒塌能力的抗倒塌指标概念,最后建议了提高圈梁-构造柱约束砖砌体房屋抗地震倒塌能力和实现合理倒塌模式的若干基本措施。

EARTHQUAKE-INDUCED COLLAPSE PREVENTION CAPACITY OF BRICK MASONRY STRUCTURES CONFINED WITH TIE COLUMNS AND TIE BEAMS

Lessons learned from the Wenchuan Earthquake on May 12,2008 indicate that in addition to possessing sufficient collapse prevention capacity,the brick masonry structures should be able to collapse in such a reasonable pattern that the collapses of different structural components can follow expected sequence and the structural components enclosing particular spaces of the structure can be restrained from collapse for the maximum protection of human lives and properties when the collapse is unavoidable under the attack of a mega earthquake that largely exceeds the local seismic fortification intensity specified the code.The equivalent diagonal strut model is introduced to establish the load transfer path and the interaction between tie columns and brick walls.There seismic collapse patterns as well as the corresponding calculation methods are discussed.A confinement coefficient and a collapse prevention index are defined to reflect the confining capacity of the tie columns and tie beams and the collapse prevention capacity of brick walls.Finally,several fundamental measures for the improvement of seismic collapse prevention capacity of the brick masonry buildings confined by tie columns and tie beams are suggested.