近海大气环境下钢框架自振频率评估研究

Assessment of Natural Frequency of Steel Frames in Offshore Atmospheric Environment

摘要:

由于沿海地区的钢结构建筑常暴露在露天，不可避免地受到大气环境的腐蚀。本文在材料力学和结构分析的基础上，研究沿海地区钢框架结构自振频率的变化，进而对结构在近海大气环境下存在的潜在损伤进行评估。基于工字形与箱形截面，提出结构自振频率与结构构件厚度变化的关系式，并分别考虑构件内外表面腐蚀的影响。以一榀钢框架结构为例，分析其在腐蚀5、10、20年后结构前10阶自振频率的变化。分析结果表明，随着腐蚀程度的增加，结构自振频率降低的越大。研究成果可为锈蚀钢框架损伤评估提供一定的参考依据。

Abstract:

Steel space structures in coastal areas are often exposed to the open air so are inevitably subjected to atmospheric corrosion. In this paper, we draw from the fields of material science and structural analysis to present a framework for evaluating potential damage from atmospheric corrosion to steel space structures in coastal areas. We derive equations that relate structural natural frequency sensitivity to structural member thickness and consider both the inner and outer surface corrosion of the structural member. Using an actual large steel space structure as an example, we examine the feasibility of our proposed approach and assess the potential structural damage caused by atmospheric corrosion. The results demonstrate that atmospheric corrosion does not obviously affect the natural frequencies of the structure but does redistribute the stress and some of the structural members may undergo large stress changes.