钢—混凝土组合梁桥时变可靠度分析-桥梁与隧道工程专业论文.docxVIP

I I PAGE PAGE IV 摘 要 由于材料老化及超载等因素，使得既有钢—混凝土组合梁桥在服役过程中结构性能 不断退化，可靠性降低。既有钢—混凝土组合梁桥服役期的可靠性属于时变可靠性范畴， 研究钢—混凝土组合梁的时变可靠度具有重要的理论意义和工程应用价值。 本文在已有的结构抗力统计分析方法基础上，建立了钢—混凝土组合桥梁的时变抗 力模型，利用 MATLAB 平台分别编写了基于蒙特卡罗法的计算剪力键可靠度程序 MPFS 和基于 JC 法的计算剪力键可靠度程序 JCPFS，研究了不同直径和个数剪力键、不同混 凝土和栓钉强度等级在不同活恒载效应比下对剪力键可靠性的影响，并从可靠度方面来 比较不同剪力键承载力计算公式特点。 基于 AASHTO 疲劳设计规范法，通过引入疲劳抗力衰减函数，建立了钢—混凝土 组合梁桥栓钉剪力键的疲劳时变可靠度分析模型。 通过时变可靠度理论及本文建立的时变抗力模型，对一座钢—混凝土组合简支梁桥 进行了承载能力体系时变可靠度和疲劳时变可靠度分析。分析发现，钢梁强度衰减是影 响钢—混凝土组合结构时变可靠度的重要因素；混凝土时变强度的变异性对钢—混凝土 组合梁的承载能力可靠指标影响较大，可靠指标随变异系数的增大而减小；钢梁时变强 度的变异性对钢—混凝土组合梁的承载能力可靠指标基本无影响；恒载和活载变异系数 对组合梁承载能力时变可靠度的影响随着时间的推移越来越小；等效应力变异系数越 小，疲劳可靠指标衰减的越剧烈。 关键词：钢—混凝土组合梁桥、时变可靠度、体系可靠度、栓钉剪力键 Abstract The structural performance of existing steel-concrete composite beam bridges gradually deteriorates during active time due to material aging, overload or other factors, and structural reliability decreases. The reliability of existing steel-concrete composite bridge is time-variant. Time-variation reliability research of steel-concrete composite beam bridges has important theoretical significance and engineering application value. This paper referenced the statistical analysis method of existing structural resistance, built the time-variation resistance model of steel-concrete composite bridges. Using MATLAB to compile reliability calculation program MPFS based on Monte carlo method and JCPFS based on JC method. Researching the influence of shear connectors’ reliability of different diameter and number of shear connectors, concrete and shear connectors strength level under different ratio of live load and dead load. And compared characteristic of different shear connectors’ bearing capacity calculation formulas based on reliability. To consider time-variation fatigue strength of concrete, shear connectors and steel, building fatigue time-variation reliability analysis model of steel-concrete composite bridges based on AASHTO fatigue design standard method. For a steel-concrete composite beam bridge do capacity