钢桥自适应有限元分析

钢桥自适应分析是钢桥塑性分析理论的一个新探讨,它研究在超出弹性极限的重复荷载作用下结构的弹塑性行为,由于其荷载方式接近桥梁结构的实际承载方式,自适应分析更为真实地反映结构的塑性抗弯承载能力。为推广自适应理论在钢桥结构中的应用,以连续实腹钢梁桥为对象,基于Timoshenko梁弹塑性理论,采用分层梁单元,编制有限元程序模拟结构自适应全过程,以求解结构自适应极限承载力,并与相关文献进行算例对比。分析结果表明：对连续钢梁自适应极限荷载的求解问题,非线性有限元程序运用方便,且精度较高;分层梁单元能够很好地表现塑性区的扩展情况;同时也证明自适应极限状态是一种临界状态。

Shakedown Finite Element Analysis of Steel Girder Bridges

The shakedown analysis of steel girder bridges is a new research direction of the plastic theory for steel girder bridges.Shakedown theory studies a structure's elasto-plastic behavior under repeated loads which exceed the elastic limit loads but are less than the collapse loads.Because this loading mode is very close to the actual loading mode that a bridge is subjected to,the shakedown analysis can reflect a structure's bearing capacity more factually.In order to extend the application of shakedown theory in steel girder bridge structure,a finite element program is constructed.The program bases on elastic-plastic theory of the Timoshenko beam,and uses divided-layer-beam element.It can model the whole shakedown process of a structure and get the shakedown limit load.Some proving examples then were analyzed.Compared with corresponding references,the analytical results indicate that the program can simplify the calculation of the shakedown limit load with a high precision;the dividedlayer-beam element can simulate the extension of plastic zero very well.The results also prove the shakedown limit state is a critical state.