LRFD(Load and resistance factored design)荷载和阻力系数法是一种广泛应用于土木工程建设和其他领域的研究方法,它是建立在设计荷载和实际阻力之间相互关联特性的理论基础上的一种计算手段。在岩土工程勘察设计中,LRFD法也能够作为...LRFD(Load and resistance factored design)荷载和阻力系数法是一种广泛应用于土木工程建设和其他领域的研究方法,它是建立在设计荷载和实际阻力之间相互关联特性的理论基础上的一种计算手段。在岩土工程勘察设计中,LRFD法也能够作为一种有效的辅助方法解决很多实际问题,以计算桩壁侧阻力的为例,简单探究了LRFD法在实际工程建设中的应用,结合已有的钻探方法和结果,基于数值模拟方法 Matlab的命令,得到了很好的研究结果。展开更多
介绍载荷抗力系数设计(Load and Resistance Factor Design,LRFD)方法的背景和原理。在此基础上,以某深水半潜式钻井平台的舵机基座强度分析为例,基于挪威船级社海洋结构物设计规范和经典力学理论,展示LRFD方法在海洋结构物局部结构强...介绍载荷抗力系数设计(Load and Resistance Factor Design,LRFD)方法的背景和原理。在此基础上,以某深水半潜式钻井平台的舵机基座强度分析为例,基于挪威船级社海洋结构物设计规范和经典力学理论,展示LRFD方法在海洋结构物局部结构强度分析中的实际应用,表明该方法的特点。展开更多
This paper investigates the impact of differential foundation settlement on the reliability of bridge superstructure based on loads and resistances statistical properties in Missouri State.Maximum deterministic differ...This paper investigates the impact of differential foundation settlement on the reliability of bridge superstructure based on loads and resistances statistical properties in Missouri State.Maximum deterministic differential settlement is often used in current AASHTO LRFD(load and resistance factored design)specification.However,the expected foundation settlement is quite different from the actual settlement due to the soil’s large variability.Therefore,it makes sense to consider settlement as a random variable.In this paper,a lognormal distribution with coefficient of variation of 0.25 of random settlement is considered in reliability analysis based on limited previous studies.Dead and live loads are modeled as random variables with normal and Gumbel Type I distributions,respectively.Considering the regional traffic condition on Missouri roadways,the live load effect on existing bridges based on weight-in-motion data is also investigated.The calibrated resistance statistical properties such as bias and COV(coefficient of variance)are used for reliability analysis.Total 14 existing bridges based on Strength I Limit State are analyzed.Since no differential settlement is considered in the past designed bridges in Missouri,small differential settlement can significantly reduce the reliability indices of the superstructure,depending upon the span length and rigidity of the girder.The analysis results also show that the reliability of existing steel-girder bridges is consistently higher than prestressed concrete and solid slab bridges;the shorter and stiffer the spans,the more significant the settlement’s effect on the reliability of bridge superstructures;As the span length ratio becomes less than 0.75,the girder and solid slab bridges’reliability drops significantly at small settlements.展开更多
文摘介绍载荷抗力系数设计(Load and Resistance Factor Design,LRFD)方法的背景和原理。在此基础上,以某深水半潜式钻井平台的舵机基座强度分析为例,基于挪威船级社海洋结构物设计规范和经典力学理论,展示LRFD方法在海洋结构物局部结构强度分析中的实际应用,表明该方法的特点。
文摘This paper investigates the impact of differential foundation settlement on the reliability of bridge superstructure based on loads and resistances statistical properties in Missouri State.Maximum deterministic differential settlement is often used in current AASHTO LRFD(load and resistance factored design)specification.However,the expected foundation settlement is quite different from the actual settlement due to the soil’s large variability.Therefore,it makes sense to consider settlement as a random variable.In this paper,a lognormal distribution with coefficient of variation of 0.25 of random settlement is considered in reliability analysis based on limited previous studies.Dead and live loads are modeled as random variables with normal and Gumbel Type I distributions,respectively.Considering the regional traffic condition on Missouri roadways,the live load effect on existing bridges based on weight-in-motion data is also investigated.The calibrated resistance statistical properties such as bias and COV(coefficient of variance)are used for reliability analysis.Total 14 existing bridges based on Strength I Limit State are analyzed.Since no differential settlement is considered in the past designed bridges in Missouri,small differential settlement can significantly reduce the reliability indices of the superstructure,depending upon the span length and rigidity of the girder.The analysis results also show that the reliability of existing steel-girder bridges is consistently higher than prestressed concrete and solid slab bridges;the shorter and stiffer the spans,the more significant the settlement’s effect on the reliability of bridge superstructures;As the span length ratio becomes less than 0.75,the girder and solid slab bridges’reliability drops significantly at small settlements.
