全跨与半跨荷载组合下两铰圆弧钢拱承载力计算与可靠度分析

发布时间：2019-05-28 06:08

【摘要】：钢拱结构是建筑结构中常见结构形式之一,由于大跨度钢结构自重小、跨度大、空间利用率高,近年来在所有在建项目中占比越来越大。可一旦设计不当使钢拱结构发生破坏将会给国民经济带来重大损失,因此对钢拱结构进行研究具有非常重要的现实意义。本文主要针对两铰圆弧钢拱结构承受全跨与半跨荷载组合下的极限承载力进行研究。为研究不同因素对圆弧钢拱结构承载力的影响,文章使用日本学者Kuranishi和Yabuki所提出的方法、基于一致缺陷有限元方法、完善结构有限元方法、考虑二阶效应强度设计方法与我国《拱形钢结构技术规程》所建议的方法进行对比。结果分析表明,采用上述不同方法所计算的结构极限承载力存在较大差异,且当半跨荷载占较高比重时,《拱形钢结构技术规程》与其他方法相比,其计算结果偏于不安全。可靠度是衡量结构是否安全的重要指标。积分方法是求解结构可靠度的常用方法之一,对于失效模式由串联模式与并联模式混合而成的混联结构体系可靠度求解方法的探讨,相关学者研究尚不充分。文章提出了一种快速确定混联体系失效区域的实用方法,应用该方法,对比分析了不同积分方法求解复杂混联体系结构可靠度的精度和效率。算例分析表明Gauss型求积公式(Gauss-Legendre积分、Gauss-Hermite积分)的计算效率要优于Newton-Cotes型求积公式(梯形公式、辛普森公式)与蒙特卡罗积分方法;验算点的位置和坐标系的选择对Gauss-Hermite积分的计算精度影响较大;Gauss-Legendre积分的计算精度与积分区间有较大关联,若积分区间选择不合理计算结果误差较大。梯形公式由于计算较为简便、计算结果较为稳定,因而在求解复杂结构的可靠度时较有优势,在能容许较大的计算量时文章建议采用梯形积分方法求解复杂结构可靠度。目前钢拱结构荷载效应系数取值比较单一,而在半跨荷载占较高比重时结构的可靠性会偏低,另外钢拱结构失效方程的不确定性特性也会给结构的可靠度水平产生影响。文章通过计算钢拱结构可靠指标,进一步确定结构的安全系数可为设计提供参考依据。
[Abstract]:Steel arch structure is one of the common structural forms in building structures. because of its small weight, long span and high space utilization ratio, steel arch structure accounts for more and more of all the projects under construction in recent years. However, once the steel arch structure is destroyed by improper design, it will bring great losses to the national economy, so it is of great practical significance to study the steel arch structure. In this paper, the ultimate bearing capacity of two-hinged circular arc steel arch structure subjected to full-span and half-span loads is studied. In order to study the influence of different factors on the bearing capacity of circular arc steel arch structure, this paper uses the method proposed by Japanese scholars Kuranishi and Yabuki to perfect the structural finite element method based on the uniform defect finite element method. The second-order effect strength design method is compared with the method proposed in the Technical Specification for Arch Steel structures in China. The results show that the ultimate bearing capacity of the structure calculated by the above different methods is quite different, and when the half-span load accounts for a high proportion, the calculation results of the Technical Specification for Arch Steel structures are unsafe compared with other methods. Reliability is an important index to measure the safety of structures. Integral method is one of the common methods to solve structural reliability. The discussion on the reliability solution method of hybrid structure system, which is composed of series mode and parallel mode, is not fully studied by relevant scholars. In this paper, a practical method for quickly determining the failure zone of hybrid systems is presented. By using this method, the accuracy and efficiency of different integral methods for solving the reliability of complex hybrid systems are compared and analyzed. The analysis of numerical examples shows that the computational efficiency of Gauss type Quadrature formula (Gauss-Legendre integral, Gauss-Hermite integral) is better than that of Newton- Cotes type Quadrature formula (ladder formula, Thompson formula) and Monte Carlo integral method. The position of checking point and the selection of coordinate system have great influence on the calculation accuracy of Gauss-Hermite integral, and the calculation accuracy of Gauss-Legendre integral is closely related to the integral interval, and if the integral interval selection is unreasonable, the error of calculation result is large. Because the calculation of ladder formula is simple and the calculation result is stable, it has more advantages in solving the reliability of complex structure. In this paper, it is suggested that the ladder integral method should be used to solve the reliability of complex structure when a large amount of computation can be allowed. At present, the load effect coefficient of steel arch structure is relatively single, but the reliability of the structure will be lower when the half-span load accounts for a high specific gravity. In addition, the uncertain characteristics of failure equation of steel arch structure will also have an impact on the reliability level of the structure. In this paper, by calculating the reliability index of steel arch structure, the safety factor of the structure can be further determined, which can provide a reference for the design.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU391

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