高速铁路连续梁-拱桥拱梁竖向刚度比分析

Analysis of Arch-beam Vertical Stiffness Ratio of the Continuous Beam-arch Composite Bridge on a High Speed Railway

研究目的:在梁-拱组合体系桥梁设计中,拱梁刚度比对整体结构的受力和变形、动力特性、稳定性以及施工方法有较大影响,设计中应根据具体情况,合理选择拱梁的相对刚度,以达到最优的结构体系。已有梁-拱组合体系结构性能研究中,拱梁刚度比一般认为是拱肋和主梁构件抗弯刚度的比值,这种计算方法只是简单地将拱和梁的抗弯能力进行比对,并不能准确反映结构刚度。因此,为了真实反映梁-拱组合桥的拱梁相对刚度,有必要基于力学原理科学计算拱梁竖向刚度比,并探讨其对结构性能的影响及结构相关设计参数。研究结论:(1)采用拱肋与主梁跨中竖向刚度之比值作为拱梁竖向刚度比指标更能全面反映梁-拱组合结构的刚度特性;(2)随着拱梁竖向刚度比的提高,边跨主梁的静活载挠度不断增大;在拱梁刚度比增加到一定数值后,边跨主梁挠跨比将大于主跨,结构竖向刚度则可能由边跨主梁刚度控制;(3)随着拱梁刚度比的增大,二期恒载和活载作用下,拱肋分担荷载也逐渐增大,且变化速度明显由快变慢;当拱梁竖向刚度比达到0.621 2后,拱肋分担荷载比增长速度基本趋于稳定;(4)可根据拱肋和主梁竖向刚度比将连续梁-拱组合体系桥划分为3类,即拱梁竖向刚度比小于0.3时,为强梁弱拱桥;大于1.5时,为强拱弱梁桥;介于0.3~1.5之间,为强梁强拱桥;(5)在连续梁-拱组合体系桥设计时,随着拱梁刚度比的增大,宜同步减小边跨与中跨的跨径比;合理边中跨径比上限值y与拱梁竖向刚度比x的关系可取为y=0.414 4x^(-0.105);(6)本研究结果可供梁-拱组合体系桥结构分析和工程设计参考。

Research purposes:In the design of beam-arch combination system bridges,the arch-beam stiffness ratio has a greater influence on the force and deformation,dynamic characteristics,structural stability,and construction methods of the overall structure.The arch-beam vertical stiffness ratio should be selected reasonably according to the specific situation to achieve the optimal structural system.In the existing beam-arch structure performance research,the arch-beam stiffness ratio is generally considered to be the ratio of the flexural stiffness of the arch rib and the main beam,and the stiffness of the structure can not be accurately reflected by the calculation method.In order to truly reflect the relative stiffness of the arch and girder of the beam-arch combination bridge,it is necessary to scientifically calculate the arch-beam vertical stiffness ratio according to the mechanical principles,and discuss its influence on the structural performance and related design parameters.Research conclusions:(1) The stiffness characteristics of the arch-beam composite structure can be fully reflected when the arch-beam vertical stiffness ratio is calculated by the ratio of the vertical stiffness of the arch rib to the main girder in the mid-span.(2) Accompanying with the increase of the arch-beam vertical stiffness ratio,the static live load deflection of side span is gradually increased.The deflection-span ratio of the side span will be greater than that of the main span,and the vertical stiffness of the structure may be controlled by the side span stiffness of the main beam when the arch-beam stiffness ratio achieving a specific value.(3) The load sharing by the arch ribs gradually increases under the effects of the self-weight of accessory equipment and live load with the increase of the arch-beam stiffness ratio,and the speed changes obviously from fast to slow.The increase speed of load-sharing ratio of the arch ribs will be basically stable when the arch-beam vertical stiffness ratio is greater than 0.621 2.(4) The continuous beam-arch combination system bridge can be divided into three types according to the vertical stiffness ratio of the arch ribs and the main beam.It is a strong beam and weak arch bridge when the vertical stiffness ratio of the arch beam is less than 0.3;it is a strong beam and strong arch bridge when the stiffness ratio of the arch beam is between 0.3 and 1.5;it is a strong arch and weak beam bridge when the arch-beam stiffness ratio is greater than 1.5.(5) The span ratio between the side and the middle span should be reduced simultaneously accompanying with the increase of the arch-beam stiffness ratio in the design of beam-arch combination system bridges.The relationship between the upper limit(y)of the reasonable side-mid span ratio and the vertical stiffness ratio(x)of the arch-beam can be taken as y=0.414 4x^(-0.105).(6) The research results can be used as a reference for the structural analysis and engineering design of beam-arch combination system bridges.