某既有薄弱钢结构BRB减震加固对比研究

Comparative study on seismic strengthening of certain existing weak steel structure with BRB

某既有钢结构商场多次增层改造,因施工水平较差和外部环境腐蚀,其薄弱节点众多,安全隐患极大。采用BRB减震加固前,须考虑薄弱节点对减震效果的影响。为减少薄弱节点加固量,借鉴美国钢结构设计方法,采用3种节点处理方案。运用SAP2000进行时程分析,对比梁柱薄弱节点全刚接、半刚接、全铰接对BRB减震效果的影响。结果表明:梁柱节点全刚接时BRB减震加固效果优异,但造价和施工量较大;仅外部节点刚接可大幅减少节点加固量,且BRB减震效果良好;全部节点铰接不利于BRB消能减震,大量节点在BRB屈服耗能前失效,结构安全性较差。研究发现:沿弱轴单向布置BRB可平衡结构X和Y向的侧向刚度,减少BRB用量;少量BRB减震时加固效果较差,大量梁柱节点失效破坏。

An existing steel structure shopping mall has been reconstructed for many times.The poor construction level and external environment corrosion lead to many weak nodes,causing great potential safety hazard.Before using BRB for seismic reduction and reinforcement,the influence of weak nodes on seismic reduction effect must be considered.In order to reduce the reinforcement amount of weak joints,three schemes of joint treatment are adopted based on American steel structure design method.SAP2000 was used for time-history analysis to compare the effects of all-rigid connection,half-rigid connection and all-hinge connection of weak beam-column joints on BRB damping effect.Studies have shown that BRB has excellent seismic reduction and reinforcement effect when the beam-column joints are fully rigid,but the cost and construction amount are large.Only external connections can greatly reduce the amount of reinforcement,and BRB damping effect is good.The hinged joints of all nodes are not conducive to BRB energy dissipation,and a large number of nodes fail before BRB yield energy dissipation,resulting in poor structural safety.It is found that BRB can be arranged in one direction along the weak axis to balance the lateral stiffness of the structure in X and Y directions and reduce the amount of BRB.A small amount of BRB damping reinforcement effect is poor,and a large number of beam-column joints fail.