An improved Chinese load code method for the evaluation of wind‐induced base shear force on base‐isolated buildings

The Structural Design of Tall and Special Buildings Pub Date : 2024-09-13 DOI:10.1002/tal.2173

Hehong Zhou, Wenchen Lie

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Abstract

The isolator units in a seismically isolated structure shall have a surplus yield strength under wind loads. The isolation interface must have enough strength to state at an elastic stage under wind loads. This necessitates an accurate evaluation of wind‐induced base shear force. Initially, to calculate the equivalent static wind load (ESWL) and the base shear force of a base‐isolated building, the validity of the inertial wind load (IWL) method and Chinese load code (CLC) method, the simplification based on the IWL method, are examined via comparison with response‐history analysis results. Comparative analysis reveals that the IWL method was more accurate in evaluating the ESWL and the base shear force of base‐isolated building, while the CLC method underestimated them due to the following reasons: inaccurate fundamental modal shape, a reduced peak factor, the omission of the ESWL contribution from the isolation interface, and flawed assumptions of uniform mass distribution. Subsequently, an improved CLC method that combined the exponential modal shape and first modal generalized mass modification coefficient is proposed and verified by a case study. Compared with the CLC method, the fluctuating base shear force calculated by the improved CLC method increased by 10% in the case study. Finally, the effect of non‐uniformly distributed mass is further considered in the proposed method by devising a mass conversion coefficient, and the case study has also validated this method. Without considering the effect of the non‐uniform mass, the fluctuating base shear force will be underestimated by 7.8% in the case study.

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中国荷载规范的一种改进方法，用于评估基底隔震建筑物的风致基底剪力

隔震结构中的隔震单元在风荷载作用下应具有剩余屈服强度。隔震界面必须具有足够的强度，以便在风荷载作用下处于弹性状态。这就需要准确评估风引起的基底剪力。最初，为了计算基底隔离建筑的等效静风荷载（ESWL）和基底剪力，通过与响应历史分析结果的比较，研究了惯性风荷载（IWL）法和基于 IWL 法简化的中国荷载规范（CLC）法的有效性。对比分析表明，IWL 方法在评估基底隔震建筑的 ESWL 和基底剪力时更为准确，而 CLC 方法则由于以下原因而低估了 ESWL 和基底剪力：基本模态形状不准确、峰值系数降低、遗漏了隔震界面的 ESWL 贡献以及均匀质量分布假设存在缺陷。随后，提出了一种结合指数模态形状和第一模态广义质量修正系数的改进型 CLC 方法，并通过案例研究进行了验证。在案例研究中，与 CLC 方法相比，改进的 CLC 方法计算出的波动基底剪力增加了 10%。最后，通过设计质量换算系数，提出的方法进一步考虑了非均匀分布质量的影响，案例研究也验证了这一方法。如果不考虑非均匀质量的影响，案例研究中的波动基底剪力将被低估 7.8%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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The Structural Design of Tall and Special Buildings

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