带构造柱组合砖墙出平面偏心受压性能及设计方法

Behavior and design of brick wall with structural columns under out-of-plane eccentric compression

为研究带构造柱组合砖墙出平面偏心受压性能,设计7个空间模型并对其进行静力加载试验。模型均由2片带构造柱组合砖墙及连接两片墙中部构造柱的加载梁和连接两端部构造柱的横向圈梁组成,在一定程度反映实际工程的空间作用。模型试验过程显示,随荷载增大逐步使梁跨中截面开裂、塑性铰出现、挠度剧增,迫使梁柱节点转动,以致构造柱连同墙体因偏心受压而开裂、屈服并出现塑性铰,圈梁扭矩裂缝与墙体斜裂缝贯通,组合墙显著外突而破坏。研究结果表明:上部结构的约束、轴压比的增大及偏心距的减小有利于柱、圈梁和砌体墙共同工作性能的发挥;沿墙长方向截面应力的传递和重分布十分明显,表现出构造柱与砖墙的较强协同工作能力;在梁、柱、墙和圈梁截面刚度、构造柱间距和材料强度等诸多因素中,梁刚度是控制模型极限承载力的主要因素。最后提出了关于带构造柱组合砖墙出平面偏心受压时的设计方法,即将组合墙简化为柱、将楼(屋)盖梁简化为横梁的组合框架模型进行内力分析和正截面承载力计算。该设计方法采用与现行砌体规范关于钢筋混凝土(或砂浆)面层的组合墙承载力计算公式相同的模式,但对计算单元与组合框架柱截面宽度、压区钢筋与砌体强度的取值方法等做了新的界定。本研究可为砌体结构设计规范的补充完善提供试验和理论依据。

Seven spatial models were designed and static load testing was carried out to study the eccentric compression performance of combinations of brick wall with structural columns.Each model was made up of two combined brick walls with structural columns.To reflect the actual loading condition,the loading beams were used to connect the central structural columns between two walls and the vertical ring beams were connected the structural columns at the two ends.The paper reports the testing observations in details.The research results indicate that the constraints of superstructure,the increase of axial-compressive ratio and the decrease of eccentric distance contribute the combined working performance of column,ring beam and brick masonry wall.The obvious delivery and re-distribution of the cross-section stress along the wall exhibit the strong interaction of the brick wall and structural columns.Among the stiffness of beams,columns,the wall and ring beam cross-section,structural columns spacing and material property,the beam stiffness is the principal factor to control the ultimate loading capacity of the testing model.Finally,the paper proposed a design method for the combined brick wall with structural columns.The method adopted the inner force analysis and the cross-section bearing capacity calculation on the combined frame model which simplified the combined wall to the column and simplified the floor（roof） to the lateral beam.This design method used the same calculation mode of the reinforced concrete（or mortar） layer of the combination of wall bearing capacity in the existing Code for Design of Masonry Structures,but made a new definition for the analytical element together with combination of framework of a section width,compressive region reinforcement and the value of the masonry strength.This research result is useful for the further improvement of the design specifications.