一级抗震预应力型钢混凝土空腹桁架转换层框架结构三道防线抗震设防设计方法

基于"强化转换层及其下部、相对弱化转换层上部"的抗震设计理念,提出了一级抗震大跨度预应力型钢混凝土(PSRC)空腹桁架转换层框架结构"三道防线抗震设防"的设计目标,明确了三道防线的具体划分方法、各防线内力调整措施初步方案以及主要抗震性能的量化控制指标.然后,以两榀不同上抬层数的8度(0.2g)一级抗震的两跨PSRC空腹...

Three-line defense seismic fortification design method for first seismic grade frame with prestressed steel reinforced concrete vierendeel truss transfer storey

Based on the seismic design idea of ‘strengthening transfer storey and its lower part,weakening its upper part relatively’,a design objective of ‘three-line defense seismic fortification’was proposed for first seismic grade frame with prestressed steel reinforced concrete( PSRC) vierendeel truss transfer storey. At the same time,a division method of the three-line defense was proposed,and a preliminary scheme of internal force adjustment measures and main quantitative controlling performance parameters for each line were given. After that,two first grade earthquakeresistant two-span PSRC vierendeel truss transfer storey frames with different numbers of upper storeys were studied under an eight degree( 0. 2 g) seismic fortification level. Then,based on the results from the elasto-plastic timehistory analysis of the structures designed with the preliminary scheme under rare earthquakes,new design schemes,i. e.,increasing the moment amplification factor and increasing the minimum reinforcement ratio for the steel reinforced concrete transfer column were proposed to avoid significant plastic hinges and rotation in the transfer column under rare earthquakes. The results show that the new scheme can avoid overall and local failure,and a ‘beam-column mixed hinge mechanism’can be formed to dissipate energy mainly with the beam hinges in first line defense under rare earthquakes. The quantitative controlling requirements are satisfied for each defense line,and the target of‘three-line defense seismic fortification’is realized. Finally,the seismic performance of the structures employing the new design scheme is studied under extreme-rarely earthquakes to further verify the effectiveness of ‘three-line defense seismic fortification’design method.