【作者】 张志新；

【导师】 贺拴海； 杨昀；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2011， 博士

【摘要】 我国目前对高墩大跨径预应力混凝土弯连续刚构桥的研究才刚刚起步。对于箱梁桥的研究,既有直桥也有弯桥,既有平面分析加局部空间分析,也有纯空间分析。但是对于弯桥预应力结构,采用纯空间分析的比较少；进一步分阶段、分工况进行空间分析的就更为缺乏。对于一般的直桥采用平面程序辅助局部空间分析即可满足设计计算要求,对于弯桥则必须采用空间分析。目前对高墩大跨弯连续刚构桥结构分析的研究主要集中在剪力滞分析、扭转分析、空间局部分析等方面,该类研究基本上是围绕单因素展开的,分析方法和成果已相对成熟,但均为“平面杆系加局部分析”和“不完全空间的三维单元”,无法达到全结构的仿真分析。本文为西部交通建设科技项目“高墩大跨径弯桥设计与施工技术的研究”的理论支撑,利用项目组自编的桥梁结构空间分析软件(BridgeKF),将空间实体单元提高到梁单元的简单程度,实现了预应力自动计算、分阶段模拟施工过程、自动动态规划活载；给出了基于BridgeKF的实体单元分析的建模方法,针对高墩大跨径预应力曲线连续刚构箱梁桥结构进行了大量的数值计算分析,系统地研究了此类桥梁的空间力学行为规律,为高墩大跨径弯桥设计和施工打下了理论基础。本文的主要研究工作有：在国内外研究成果基础上,对高墩曲线连续刚构箱梁桥空间行为进行了系统研究,为了符合工程设计习惯,紧密结合工程实际,在对高墩曲线连续刚构箱梁的荷载、温差、强迫位移、收缩徐变、动态规划、预应力及其损失和分阶段施工模拟等进行预分析后,主要针对高墩曲线连续刚构箱梁的扭转、剪力滞效应、横向力学行为、薄壁墩力学行为和强迫位移下结构的反应等五个方面进行了深入探讨：(1)箱梁扭转方面主要研究了弯曲半径对箱梁扭矩、纵向弯矩、横向弯矩、竖向剪力的影响及变形分析,重点分析扭转效应。(2)剪力滞效应方面主要研究了半径、墩身高度、梁高比、宽跨比等因素对弯桥剪力滞效应的影响规律。(3)横向分析方面重点研究了箱梁结构横向应力和横向位移对荷载、弯曲半径、预应力和温差变化的反应。(4)薄壁高墩方面重点研究了曲线连续刚构箱梁结构的恒载、弯曲半径、预应力和温差变化对薄壁墩的影响。(5)强迫位移方面重点研究了结构边支点和主墩强迫位移对上部箱梁的影响。主要创新性成果有：1、经过对不同半径的高墩曲线连续刚构箱梁进行分析,得出了弯曲半径对箱梁空间内力的影响规律。恒载作用下,受半径影响最大的是扭矩,其次是横向弯矩,对纵向弯矩和剪力影响较小；弯曲半径越小,扭矩越大,内外侧位移差越大,当弯曲半径小于800m时,扭矩和内外侧位移差增长趋势变大。活载作用下,受半径影响最大的是横向弯矩,其次是扭矩。半径小于800m(弯曲角大于18.3°)后,对各项内力指标影响加剧。2、通过对高墩曲线连续刚构箱梁剪力滞效应的研究,给出了曲率半径、墩身高度、梁高比、宽跨比等因素对剪力滞效应的影响规律。恒载作用下,弯曲半径对箱梁顶底板的剪力滞系数影响很大,随着半径的减小,内外径侧剪力滞效应响应增强。当半径大于1200m时,半径对箱梁剪力滞影响可忽略不计,当半径大于250m时,如不考虑曲率影响,采用平面程序按直桥计算的误差在25%以内。剪力滞还受墩高、宽跨比、梁高比因素影响。墩越高,剪力滞效应越明显,当高度达到40m后,对剪力滞影响趋于稳定。宽跨比越大,剪力滞效应越明显；梁高比越小,剪力滞影响越明显。3、箱梁结构横向应力和横向位移对荷载、弯曲半径、预应力和温差变化的反应的研究表明：横向应力受弯曲半径影响较大；半径越小,顶底板横向效应越明显,结构向内侧的位移越大；受宽跨比、升降温的影响也较大。4、曲线连续刚构箱梁结构的恒载、弯曲半径、预应力和温差变化对薄壁墩的影响研究表明：薄壁墩的内力受自重、上部预应力、弯曲半径、墩高、墩截面形式、温度等影响,半径改变对墩侧向及纵向弯矩影响较大；墩高越高,侧向、纵向弯矩越小。中墩的位移主要是横向,在最大悬臂状态时达到最大；半径减小,横向位移增大。5、结构强迫位移对上部箱梁的影响研究表明：边跨支座下沉对边跨的扭矩影响很大,当边跨内侧支座下沉1cm时,边跨扭矩是成桥的2倍。这点必须引起工程技术人员的足够重视。本文研究成果对我国曲线高墩大跨连续刚构桥的内力分析计算、内力影响因素识别、结构设计等具有指导意义,可为我国高墩大跨预应力刚构桥设计施工提供参考。更多还原

【Abstract】 The study on prestressed concrete curved continuous rigid frame bridge with high pier& long span is just getting started in our country at present. Research on box-girder bridge includes both straight ones and curved ones, the research methods not only includes facet analysis with local space analysis, but also includes pure spatial behaviour analysis. But with regard to the pre-stressed structure of curved bridge, the method of pure spatial analysis is used lesser; the further spatial analysis based on grading and working conditions is much lacked. For the ordinary straight bridges, the adoption of planar program with local space analysis can meet the demand of design & calculation, while for the curved ones, it is necessary to use spatial calculation procedure. At present, study on analysis of internal force for high pier & long span curved continuous rigid frame bridge mainly focuses on analysis on shear lag, torsion and local space etc. This kind of study proceeds its analysis around single factor, the methods of single-factor analysis and its achievement are relatively mature, but as they are all the methods of "planar linkage system with local analysis" and "three-dimension element of incomplete space", they can’t reach the simulation analysis of complete space.This paper is the theoretical support of the science & technology project on transportation construction of western China:"Study on Design & Construction Technology of High Pier & Long Span Curved Bridge". Making use of BridgeKF developed by the project team, this research raise the spatial solid analysis to the simple degree of girder element, and makes the automatic calculation of pre-stress, simulation of work progress by stages, automatic dynamically programming for live load; This article provides the modeling method based on the solid element analysis of BridgeKF. This article provide the technical tool and the method for further using it to study the high pier& box-girder continual rigid frame curved bridge’s spatial behavior, and lay the foundation; By way of the massive numerical calculus analysis to prestressed concrete curved continuous rigid frame bridge structure with high pier & long span, this paper study on internal force change rule of this kind of bridge systematically, and build the rationale for the design and the construction of curved continuous rigid frame bridge with high pier& long span. The main work include:Based on the home and abroad achievements, a systemic research on spatial behaviour of curved continuous rigid frame box-girder bridge with high-pier is made. In order to accord with the habit of engineering design, after a pre-anlaysis of load, difference in temperature, enforced displacement, shrinkage and creep, dynamic programming, prestressing force and it’s losses and simulation in the stage of construction, discuss in depth from the above 5 aspects, analysis of box girder torsion and shear lag of box girder, box girder transverse analysis, analysis of spatial of thin-wall pier and forced displacement of box girder:(1) Analysis of box girder torsion mainly studies the influence of bend radius to box girder torque, vertical bending moment, lateral bending moment, vertical shear force and the deformation analysis, emphasizes on torsion effect. (2) The study of shear lag mainly focuses on the law of influence of such factors as the radius, height of pier, ratio of span to height of girder, width-span ratio to the shear lag effect of curved bridge. (3) Transverse analysis emphasizes on the analysis of lateral stress of the box girder structure and lateral displacement of the pier cap, the major variables are dead load, bend radius, prestressing force and temperature change. (4) Analysis of thin-wall pier lays important research on influence of curved box girder to thin-wall pier, the key changing factors include dead load, bend radius, pre-stress and temperature. (5) Forced displacement lays important analysis on influence of the forced displacement of support and main pier to the upper box girder, the key changing factors include radius and dead load. The main innovative achievements include:1. By the analysis of torsion of curved continuous rigid frame box-girder bridge with high-pier with different radius, acquire the rule of influence of bend radius to the spatial internal force of box girder. Under the action of dead load, the most affected is torque, the second is lateral bending moment, the lesser is vertical bending moment and shear; the bend radius is smaller, the torque is larger, and the gap of displacement between inner board and out board is larger, when the bend radius is less than 800m, the growth trend of torque and displacement between inner board and out board is to get bigger. Under the action of live load, the most affected is lateral bending moment, the second is torque. While the bend radius is less than 800m (bending angle over 18.3°), the influence to various index of internal force intensifies.2. By the study of shear lag effect indicate curved continuous rigid frame box-girder bridge with high-pier, acquire the influence rule of radius, height of pier, ratio of span to height of girder, width-span ratio. Under the action of dead load, the influence of bend radius to the shear lag factor at the baseboard of box girder cap, with the decrease of radius, the response of shear lag effect at inside and outside. When the radius is more than 1200m, the influence of radius to the shear lag of box girder is negligible, when the radius is over 250m, if without regard to the influence of curvature, the error calculated by planar process according to straight bridge will be within 25%. In addition, shear lag is affected by some factors such as the height of pier, width-span ratio and the ratio of span to height of girder. The pier is higher, the effect of shear lag is more obvious, when the height is up to 40m, the influence to shear lag tends to be stable. The width-span ratio is larger, the effect of shear lag is sharper; the ratio of girder span to height is smaller, the effect of shear lag is sharper.3. Research of the lateral stress and displacement response of dead load, bend radius, pre-stress and temperature change shows:the lateral stress is much affected by bend radius; the radius is smaller, the lateral effect of baseboard of box girder cap is more obvious, and the displacement towards inside is larger. The lateral stress is relatively affected by width-span ratio and heating/cooling.4 Study on influence of dead load, bend radius, pre-stress and temperature change of curved continuous rigid frame box-girder bridge structure to thin-wall pier shows:The internal force of thin-wall pier is affected by its dead weight, upper pre-stress, bend radius, height of pier, cross section shape and temperature etc., the change of radius has much impact on side and vertical bending moment of pier; the pier is higher, the side and vertical bending moment are smaller. The displacement of central pier is mainly on lateral direction, and it reaches the maximum in case the cantilever is biggest. When the radius decreases, the lateral displacement increases.5 Research on influence of structure’s forced displacement to the upper box girder shows: the subsidence of side-span support has great impact on the torque of side-span. When the support at the inner side of side-span sinks in lcm, the torque of side-span will be twice of the one of integrated bridge.The research result of this article is a guidance to studies on such fields as the internal force analysis and calculation, identification of factors influencing to internal force, structure design for high pier & long span curved continuous rigid frame bridge in our country, and can be for reference on high pier & long span pre-stressed rigid frame bridge design and construction.更多还原