智慧梁场模块化预制简支T梁可靠度分析

Reliability Analysis of Modular Prefabricated Simply-supported T-beams in Smart Beam Plant

我国预制简支T梁设计规范采用基于概率的极限状态设计方法,在设计方程中采用分项系数,但在设计与施工制造过程中存在许多不确定性。智慧梁场采用新型计算机信息控制技术,实时监控梁体的施工过程,实现梁体的自动化控制,以确保梁体施工质量。根据预定的桥梁安全和经济效益要求,基于智慧梁场模块化预制简支T梁信息数据,对大规模数量的简支T梁的可靠性进行校准,在有效提高施工质量和安全性的前提下,还可以根据施工现场的实际情况自动调整施工工艺,以提高施工效率与节约工程造价。通过建立考虑到多个参数(活载与恒载比、梁跨径、梁间距、混凝土等级、钢筋等级、设计车道数、配筋率、桥梁荷载等级、设计使用年限)的可靠度计算框架,从材料和结构尺寸的统计以及恒载与活载等方面出发,结合蒙特卡罗法与一次二阶矩方法,基于极限状态方程计算出预应力T梁的可靠度,分析了各种设计参数对T梁可靠度指标的影响。同时,分析了可靠度指标对建设造价和总成本的影响,并将重要性指标引入失效成本计算,得到了同时满足安全与经济效益的预应力T梁的最优可靠度,对多目标下桥梁目标可靠度的确定提出了建议。

The prefabricated simply-supported T-beam design specification adopts the limit state design method based on probability theory in China.The itemized coefficients is applied in the design equations.There are many uncertainties during the process of design and construction and manufacturing.As a new type of computer information control technology,the smart beam plant can monitor the construction process of the girder in real time and the automatic control of the girder are realized to ensure the quality of the girder construction.According to the requirements of bridge safety and economic benefits,the construction technology is automatically adjusted by the actual conditions to improve the construction efficiency and save the project cost.A reliability calculation framework that takes into account several parameters(live load to constant load ratio,girder span diameter,girder spacing,concrete grade,reinforcement grade,number of design lanes,reinforcement ratio,bridge loading class,and design service life)is established.From the aspects of material statistics,structural dimension statistics,and constant and live loads,the reliability of prestressed T-beam is calculated by the combination of the Monte Carlo method with the firstorder second-moment method,the influence of various design parameters on the reliability indexes of the bridge are analyzed based on the reliability of prestressed T-beam.At the same time,the influence of the reliability indexes on the construction cost and total cost are analyzed.The importance index is introduced into the calculation of the fail ure cost to obtain the optimal reliability of the prestressed T-beam bridge that satisfies the safety and economic benefitsat the same time. A suggestion is proposed for the determination of the target reliability of the bridge under themultiple objectives.