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索鞍无预偏施工钢混叠合梁悬索桥全过程时变效应分析
【作者】 刘来君；
【导师】 贺拴海；
【作者基本信息】 长安大学 ， 道路与铁道工程， 2005， 博士
【摘要】 悬索桥是一种高次超静定柔性结构,其施工方法独特,结构受力、变形表现为显著的几何非线性,对温度变化、混凝土收缩徐变非常敏感。为使施工过程中和成桥后的实际状态最大限度的接近设计理想状态,时变效应作为一个敏感性因素,必须加以认真研究,及时进行修正。 本文通过对索鞍无预偏施工悬索桥结构受力特点的分析,全面阐述了索鞍无预偏施工悬索桥的计算理论,确定了成桥线形和主缆无应力长度的计算方法,采用基于悬索力学的解析迭代法和基于有限位移理论的有限元方法,系统地论述了基于索鞍无预偏施工悬索桥的主索下料长度,空缆状态及空缆标高,加劲梁吊装阶段的主塔受力、变形及锚跨张拉时机与张拉量。 论文在建立徐变收缩数学模型的基础上,通过老化理论分析、有限元逐步分析,根据实测的应变,利用平面假定,扣除混凝土收缩、徐变的影响,进而得出混凝土实际的弹性应变;在分析温度荷载的基础上,通过热传导理论,借助傅立叶热传导方程,假定边界温度函数,求解出结构的瞬态温度场,得出温度应力的实用计算方法。 论文以云南省祥临公路澜沧江索鞍无预偏施工钢混叠合加劲梁悬索桥工程为依托,研究了从裸塔状态到猫道施工状态、挂缆状态、加劲梁吊装状态整个过程的索塔偏位的成因及计算方法,分析了时变效应的影响,得出了计算混凝土实际应力的方法;结合该依托工程的特点和地理环境,制定了索塔、猫道、主缆、加劲梁的测温方案,通过对悬索桥温控计算方法的分析,得出最不利温度梯度求解公式,根据无应力索长恒定不变的原理,求解出温度作用下的主缆中、边跨垂度,并给出主缆索股调整的具体方法。分析了温度和混凝土收缩、徐变对加劲梁及成桥状态的影响,通过对锚跨张力、吊索拉力及长度、叠合梁标高的实时控制与调整,保证了主塔受力、索股间不平衡力、索股最大允许应力在控制范围内,成桥线形达到设计要求。 通过依托工程的具体应用,证明了本文研究的理论计算方法和时变效应分析方法的可靠性和有效性,本文得出的结论对大跨径悬索桥的设计、施工及施工控制提供了理论参考。
【Abstract】 Suspension bridge, a multi-hyperstatic and flexible structure, whose construction method is special. Due to the geometrically nonlinear load-deflection relationship, it is very sensitive to the influence of temperature and creep and shrinkage of concrete. In order to make the actual condition in the state of construction and completion approximate the designed ideal state best, time-dependent affection, as a sensitive factor, must be taken into studying conscientiously and then modifying in time.The calculation theories is systematic explained, the method of the line-type of completion state, zero-stress length of suspender is put forward by analysing the stress of the suspension bridge built by non-pre-bias of cable-addle. The fabrication length of the main cable, initial cable construction state and initial cable height, the stress of main tower in the stage of erecting stiffening-girder and anchor span strand jack time and displacement is systematically discussed by analytical iterative method based on mechanics of suspension bridge and the FEM method based on finite displacement theory.The paper employs the mathematic model of creep and shrinkage of concrete. Basing assumption of plane cross section, applying the aging theory and the finite element method, subtracting the portion of creep and shrinkage of concrete from the measured strains, then the real elastic strains of concrete is obtained. Analysing temperature loads effect, applying the heat-conduction theory and Fourier equation of heat-conduction, assuming border temperature function, the transient temperature field of structure is solved and the practical calculation method of temperature stress is obtained.Based on the project of LanChanGiang steel-concrete overlapping stiffening girder suspension bridge built non-pre-bias of cable-addle in XiangYun-LinChang Highway in YunNan Province, the cause of the pylon tower deviation and calculation method is studied during the whole process-from nake tower to constructing the catwalk, to hanging the cable, to erecting the stiffening girder. It analyses the time-dependentaffection, and puts calculation method of the elastic stresses of concrete forward. Combining the characteristics of the project and the Geographical environments, the temperature measurement scheme of tower> catwalk and main cable is given. By studying on the calculation method for temperature control, the formula for the worst-case temperature gradient is put forward. On the basis of the principle of invariable of zero-stress length of suspender, it solves that the slack of suspender under temperature loads and provides the detailed method of the cable adjustment of the suspender. The influence of the temperature and creep and shrinkage of concrete on stiffening girder and the state under dead loads is analysed. It assures the stress of tower, the unbalanced force between the cables and the maximum stress is under control through the real-time control and adjustment of anchorage cable tension, the stress of suspension cable and the level of stiffening girder. And the line-type of the state under dead loads is accorded with the designed requirement.The application in this project proves that the theory, the calculation method and the analytical method of time-dependent in this paper is reliable and valuable The conclusion in this paper provides references to design, construction and construction control of long span-suspension bridge.