协作体系混凝土斜拉桥主梁裂缝成因分析与加固方法研究

发布时间：2018-03-11 21:16

本文选题：协作体系混凝土斜拉桥　切入点：横向刚度　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：混凝土斜拉桥以其在稳定性和经济方面的优势成为近几十年来大跨度桥梁设计中的优选方案。然而,混凝土主梁的开裂问题也成为阻碍其发展的突出问题,成为学术界、工程界关注的焦点。为了分析斜拉桥混凝土主梁的开裂原因,本文以某协作体系独塔混凝土斜拉桥为例,主要完成如下工作:(1)分别阐述西侧74.5m协作跨、主跨无索区以及东侧49.5m协作跨的主梁裂缝分布情况,并对其裂缝形成原因进行初步分析。经分析可知:集卡车等重型车辆荷载、拉压支座的失效、49.5m跨箱梁本身横向刚度不足是造成箱梁开裂的可能原因。(2)采用有限元分析软件Midas/Civil建立全桥模型,按照设计荷载计算该桥在成桥阶段和运营阶段主梁腹板、顶板和底板的应力,以验证该桥在设计上是否满足要求。计算结果表明:主梁在成桥阶段和运营阶段受力虽然满足要求,但抗裂储备较小。(3)考虑到该桥自运营以来交通拥堵不断,且大部分为集卡车等重型车辆,因此采用有限元方法计算分析集卡车正常通行和单侧堵车两种状况下两侧协作跨主梁腹板的应力。结果表明,集卡车荷载作用下,主梁腹板应力超限的部位与开裂位置相吻合。(4)鉴于23号墩处的拉压支座在运营过程中被压碎而失效,主梁受力状态发生改变。因此本文以两侧协作跨主梁腹板、顶板和底板应力为研究对象,分析23号墩处拉压支座失效对主梁受力状态的影响。结果表明拉压支座失效会造成24号墩处顶板横向开裂。(5)鉴于单梁模型并不能反映箱梁的空间应力状态,尤其是横桥向受力状态,因此采用ANSYS建立49.5m跨实体有限元模型,对箱梁的横向受力进行计算分析。计算结果表明:顶板和底板在直腹板附近的主拉应力均远超过限值,与该跨顶板和底板的顺桥向裂缝分布位置完全一致。(6)提出拆除实体块、增设纵梁和横隔板以及张拉横向预应力钢束等四个加固措施,以改善49.5m跨横向刚度不足的状况,并采用ANSYS软件依次建立加固后的空间有限元模型,然后将加固前后的应力进行对比,从而验证此加固方案对控制该协作跨箱梁开裂的效果。计算结果表明:经加固后,箱梁横向刚度大大提高,受力满足要求。
[Abstract]:The concrete cable-stayed bridge has become an excellent selection scheme in the design of long-span bridges in recent decades because of its advantages in stability and economy. However, the cracking of concrete main beams has also become a prominent problem that hinders its development and has become a prominent problem in academic circles. In order to analyze the cracking reason of concrete main girder of cable-stayed bridge, this paper takes a single tower concrete cable-stayed bridge with a cooperative system as an example. The main work is as follows: 1) expound the 74.5 m cooperative span on the west side respectively. The distribution of cracks in the main girder in the no-cable zone of the main span and the 49.5 m cooperative span on the east side, and the causes of the cracks are analyzed. The failure of tension and compression bearing is the possible cause of box girder cracking caused by insufficient transverse stiffness of 49.5 m span box girder. The finite element analysis software Midas/Civil is used to establish the full bridge model. The main girder web of the bridge is calculated according to the design load in the stage of completion and operation. The stress of roof and floor is used to verify whether the design of the bridge meets the requirements. The calculation results show that the stress of the main beam in the stage of bridge completion and operation meets the requirements, But the anti-crack reserve is small.) considering that the bridge has been congested since its operation, and most of it is heavy vehicles, such as gathering trucks, Therefore, the finite element method is used to calculate and analyze the stress of the web plate of the main girder under the condition of normal traffic and single side traffic jam. The results show that under the load of the truck, the stress of the web plate of the main beam is calculated and analyzed. In view of the failure of the pull-compression support at Pier 23 during operation, the stress state of the main girder has changed. Therefore, this paper uses bilateral cooperation to span the web of the main girder. The stress of roof and floor is the object of study. This paper analyzes the influence of the failure of tension and compression bearing at Pier 23 on the stress state of the main girder. The results show that the failure of the bearing will cause transverse cracking of the roof at Pier 24) since the single beam model can not reflect the spatial stress state of the box girder, Especially in the transverse direction of the bridge, the finite element model of 49.5 m span is established by ANSYS to calculate and analyze the transverse force of the box girder. The calculation results show that the main tensile stress of the roof and the bottom plate near the straight web is far beyond the limit. In order to improve the condition of insufficient transverse stiffness of 49.5 m span, four reinforcement measures, such as removing solid block, adding longitudinal beam and transverse partition plate and tensioning transverse prestressed steel bundle, are put forward to improve the condition of insufficient transverse stiffness of 49.5 m span. The spatial finite element model after reinforcement is established by ANSYS software in turn, and the stress before and after reinforcement is compared to verify the effect of the reinforcement scheme on controlling the cracking of the cooperative box girder. The calculation results show that: after strengthening, the effect of the reinforcement on the cracking of the box girder is verified. The transverse stiffness of box girder is greatly improved and the force is satisfied.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.27;U445.72

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