提高多层砖混结构教学楼抗震能力的设计构思

Design Concept of Enhancing Aseismic Capacity of Multi-Storey Brick-Concrete Structure Teaching Building

从汶川大地震中,大量的中小学、幼儿园多层砖混结构教学楼普遍垮塌情况,分析单面带走廊(或外廊式)、单排教室的多层砖混结构教学楼在地震作用下整体坍塌的一个重要因素:是教学楼底层的抗震能力偏小,底层先于上层结构坍塌而引起的。其主要原因是底层墙体的计算高厚比偏大、出墙平面的刚度偏小和稳定性差。解决的途径是减小底层墙体的计算高度,采用地圈梁与配筋刚性地坪整体浇筑的方案,对底层墙起到侧向嵌固或约束作用,并以此作为底层墙的下端支点,限制各道墙体之间的相对水平位移。从而有效地减小底层墙体的计算高度、降低底层墙体的高厚比、增大出墙平面的刚度和稳定性,达到提高教学楼底层抗震能力的目的,实现"大震不倒"的抗震设防目标。

In the Wenchuan Earthquake , large numbers of multilayer brick--concrete structure teaching buildings fell down generally, including primary schools, secondary schools, and kindergartens. When we analysed the major factor of its whole collapse, which were single-sided corridors and single-row classrooms, we concluded that the anti-seismic capacity of those bottom layer was comparatively less, which caused the bottom layer collapsed before superstructure. The main reason was that its height and thickness ratio of the bottom layer wall in calculation was a bit less, but the stiffness of it which was perpendicular to horizontal direction was slightly less , and its stability was comparatively inferior . The way to solution is to decrease the height of the bottom layer in calculation, to take a measure that is the ground perimeter beam could entirely cast-in-place with rigid appurtenances of reinforcement assembly, so it could restrain or sidely mount for the bottom layer wall, and restrict the relatively horizontal displacement among all the walls, as its fulcrum of lower extremity. It can effectively diminish the height of the bottom layer wall, debate the proportion between its height and thickness ratio, and strengthen the stiffness and stability of it which is perpendicular to horizontal direction. Therefore, it can meet the demands of improving the anti-seismic capacity of the bottom layer for teaching buildings, and achieve the anti-seismic fortification goal of “earthquake will not be brought down ”.