摘要:
抗震性能化设计将传统经典规范设计法中宏观定性的设防目标转化为可量化分析的多层级性能目标,基于数值仿真类分析对结构性能表现准确评估,进而采取有针对性的措施以满足结构个性化抗震需求。其适用于各类超规超限结构,以及高性能等经典规范法难以充分发挥结构性能优势的抗震设计。首先介绍了笔者团队多年来在对抗震性能化设计、构件性能评价准则和工程应用研究的基础上提出的一种分层分级抗震性能化设计方法,详细说明了流程中涉及的设防目标确定、概念设计、性能目标设定、结构分析与性能评价等主要环节。该方法通过分层分级对结构和构件性能目标详细设定,明确地震作用分析中弹塑性分析的重要性,并以性能评估结果作为判断结构可行性的主要依据,以实现结构与构件的性能目标。随后,以一个已建成的高烈度区多层钢框架-中心支撑结构项目为例,探讨了分层分级抗震性能化设计方法的工程应用及其与传统规范设计法的区别。设计过程中基于"弱支撑"设计理念完成了概念设计、性能目标设定与初步设计,并结合计算机算法,以主要构件钢材用量最低为目标,以结构层间位移角、构件应力比与损坏等级等指标不超出预设性能目标的范围为约束条件,完成了结构分析、性能评价与设计调整的自动迭代优化。设计结果表明,采用分层分级抗震性能化方法设计的结构方案与基于传统规范法设计的原方案相比,支撑截面显著减小,支撑跨框架柱截面增加,主构件钢材用量减少约23%;罕遇地震作用下,结构整体最大层间位移角减小,最大地震总输入能量降低,塑性耗能提高;竖向构件损坏程度有效降低,而支撑损坏分布更为均匀,耗能体系更合理高效,在用钢量降低的同时,实现更好的抗震性能。
Abstract:
The performance-based seismic design (PBSD) method transforms the qualitative structural seismic precaution objectives of traditional code-based design methods into multi-level performance objectives which can be quantitatively comalyzed. Based on the numerical simulation analysis, the structural performance accuratery evaluated and targeted seismic measures are ernployed to meet specific structural demands. This method is particularly suitable for out-of-code structures and high-performance design where traditional methods are insufficient to optimize structural performance. The paper introduted a stratified and classified PBSD method, which was developed by the authors’ team through extensive research on performance-based seismic design, component performance evaluation criteria, and engineering applications. The method’s key procedures include defining seismic precaution objectives, conceptual design, performance objective setting, structural analysis, and performance evaluation. The approach emphasizes stratification and classification to refine structural and component performance objectives, integrates elasto-plastic analysis into seismic measures, and uses performance evaluation results as a foundation for design decisions, ensuring alignment with specified performance goals. A multi-storey steel concentrically braced frame located in a high seismic intensity zone was taken as a case study to illustrate the practical application of the proposed method, and the engineering applications of the stratified and classified performance-based seismic design method were discussed as well as its differences from the traditional design methods in codes. The design process began with conceptual design, performance objective setting, and preliminary design based on the "weak brace" concept. Structural analysis, performance evaluation, and design adjustments were iteratively optimized by using computational algorithms to minimize steel usage in primary components. The optimization ensured compliance with predefined performance criteria, including structural drifts, stress ratios of components, and damage grades. The results demonstrated that, compared to the original schemes based on the traditional seismic design methods in codes, in the scheme designed by the stratified and classified performance-based seismic design method, the cross sections of braces decreased significantly, while those of columns connected to braces increased. The steel usage in primary components was reduced by 23%. Furthermore, the scheme designed by the proposed method reduced structural drifts and the maximum total seismic input energy, increased plastic deformation energy dissipation, effectively minimized the damages of vertical components, and distributed the damage of braces more uniformly under rarely occurred earthquake, resulting in a more efficient and resilient energy dissipation system. In conclusion, the proposed stratified and classified PBSD method delivers superior seismic performance while optimizing material usage, demonstrating its potential for efficient and resilient structural design.