分段连续研究非光滑自复位系统的随机地震响应

STOCHASTIC SEISMIC RESPONSE ANALYSIS OF NONSMOOTHED SELF-CENTERING SYSTEMS BASED ON A PIECEWISE-CONTINUOUS FRAMEWORK

  • 摘要: 为实现抗震韧性城市目标,具有可恢复能力的结构体系受到广泛关注,自复位结构体系已成为工程抗震领域的重要研究方向。现有研究通常采用旗帜模型描述自复位结构的非线性滞回行为,但该模型具有显著的非光滑性,传统分析方法往往需引入光滑等效近似,这在强非线性条件下易引起累积误差。该文提出一种针对非光滑系统的随机响应分段连续分析方法。该方法不引入任何光滑等效近似,通过改进传统指数多项式闭合法(Exponential Polynomial Closure, EPC),建立了分段高斯矩求解策略,实现了对非光滑系统高阶统计矩的精确计算,进而系统完成了对Fokker-Planck-Kolmogorov(FPK)方程演化模型的闭合求解。与传统等效近似方法相比,该研究提出的计算框架核心在于对非光滑恢复力进行分段描述,并在此基础上实现了高阶统计量的高效精确计算,未引入额外近似误差,显著提升了计算精度。通过一系列数值算例验证,即使在地震强度增大、系统非线性增强、能量耗散机制更复杂的情况下,该方法仍能保持较高的计算稳定性与精度。该分段高斯矩计算框架具有良好的通用性与可推广性,适用于任意可分段描述的非连续恢复力系统,为此类复杂非线性系统的随机响应分析提供了统一且可靠的理论工具。

     

    Abstract: To achieve the goal of seismic‐resilient cities, structural systems with post-earthquake functional recoverability have attracted an increasing attention, and self-centering structural systems have become an important research focus in earthquake engineering. Existing studies commonly employ flag-shaped hysteretic models to describe the nonlinear restoring behavior of self-centering structures. However, such models exhibit pronounced nonsmoothed characteristics, and conventional analytical approaches usually rely on smooth equivalent approximations, which may introduce cumulative errors under strong nonlinear conditions. This paper proposes a segmented continuous stochastic response analysis method for nonsmoothed systems. Without introducing any smooth equivalent approximations, the approach proposed improves the traditional exponential polynomial closure method by developing a segmented Gaussian-moment evaluation strategy, which enables the accurate computation of high-order statistical moments for nonsmoothed systems. On this basis, a closed-form solution framework for the evolution of the Fokker–Planck–Kolmogorov equation is systematically established. Compared with conventional equivalent approximation methods, the core advantage of the framework proposed lies in the segmented representation of nonsmoothed restoring forces and of the corresponding efficient and of the accurate evaluation of high-order statistical quantities, without introducing additional approximation errors, thereby significantly enhancing the computational accuracy. Numerical examples demonstrate that the method proposed maintains its high stability and accuracy even under increased seismic intensity, enhanced the system nonlinearity, and more complex energy dissipation mechanisms. The segmented Gaussian-moment framework exhibits a good generality and extensibility, and can be applied to arbitrary nonsmoothed restoring force systems that can be described in a piecewise manner, providing a unified and reliable theoretical tool for the stochastic response analysis of complex nonlinear systems.

     

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