不同支撑形式高强钢组合偏心支撑抗震性能研究

Seismic performance of high strength steel frames with different eccentric braces based on PBSD method

耗能梁段作为偏心支撑结构的耗能元件,在大震作用下通过弹塑性变形吸收地震能量,保护主体结构处于弹性受力状态。现行规范基于强度的设计理论,为了保证耗能梁段进入塑性或破坏,梁柱构件需要进行放大内力设计,导致截面过大,而且基于强度的设计方法很难保证结构的整体破坏状态。目前,抗震设计越来越重视基于性能的设计思想,该方法能够评估结构的弹塑性反应。对于高强钢组合偏心支撑,其中耗能梁段和支撑采用Q345钢,框架梁柱采用Q460或者Q690高强度钢材,高强钢不仅带来良好的经济效益,而且能够推广高强钢在抗震设防区的应用。利用基于性能设计方法设计了4种不同形式的高强钢组合偏心支撑钢框架,包括K形、Y形、V形和D形,考虑4层、8层、12层和16层的影响。通过Pushover分析和非线性时程分析评估该结构的抗震性能,研究结果表明:4种形式的高强钢组合偏心支撑钢框架具有类似的抗震性能,在罕遇地震作用下,几乎所有耗能梁段均参与耗能,而且层间侧移与耗能梁段转角沿高度分布较为均匀。其中:D形偏心支撑具有最大的抗侧刚度,但延性较差,而Y形偏心支撑的抗侧刚度最弱,但延性最佳。

The links are fuse members in eccentrically braced steel frames(EBFs),which enter inelastic phase before other structural members and dissipate the seismic energy.Based on the force-based seismic design method,damages and plastic deformations are limited to the links,and the main structural members are required tremendous sizes to ensure elastic with limited or no damage.Force-based seismic design method is very commonly used and is found in most design codes,but it is not easy to control the structural damage patterns.Nowadays,the performance-based seismic design concept is paid more attention because it can assess the inelastic response of the structure.Q345 steel is used for links and braces and Q460 steel or Q690 steel is used for columns and beams in the eccentrically braced steel frames,the applications of high strength steels not bring out better economy and higher strength,but also widen application prospects in seismic fortification zones.The structures with four types of eccentric braces are chosen in this study,including K-type,Y-type,D-type and V-type.Four types eccentrically braced frames with 4-storey,8-storey,12-storey and 16-storey,are designed by performance-based seismic design(PBSD)method.To evaluate the seismic performance of the structures,nonlinear static and dynamic analyses are performed.Analyses results indicated that all models have similar performance;all models designed by PBSD method have the same failure mode and story drift distribution under rare earthquake.The lateral stiffness of EBF with D-type eccentric brace is highest.The ductility of EBF with Y-type eccentric brace is best but with the lowest lateral stiffness.