Designing Parameter Optimization Based On Anti-seismic Property Of Arch-auxiliary Girder Bridge

As a new developing bridge, arch-auxiliary girder bridge, which has been widelyapplied in highway and railway engineering, is a kind of beam bridge system, composedof beams, arch ribs and boom, and which mechanical character is mainly given priorityto beam while arch is auxiliary to beam. Based on Guangyuan Jialing river double-linelarge-span beam bridge, computed by large-scale finite element software, designingparameters optimization of arch-auxiliary girder bridge is further researched in theground of seismic performance, and each design parameters, on natural vibration modeand dynamic response analysis under seismic action, is compared and analyzed. what’smore, design parameters reasonable scope under the condition of same and differentbeam-arch stiffness ratio are discussed, in order to play a part and play a reference rolein such bridges in the future. Specific research contents include the following:(1) Reasonable arch and beam stiffness ratio evaluation method is explored, andseveral design parameters optimization criterion is deduced, including optimizationmethods: general analysis and comparison method based on specification limit of code,Lagrange multiplier method and minimum potential energy principle according toenergy principle, the optimization method based on least square method and probabilitymethod based on arch vibration character.(2) Structure dynamic characteristics of corresponding design parameters, under theconditions of different stiffness ratio, are compared and analyzed, and reasonable scopeof design parameter are discussed. Three kinds of different stiffness ratio—the samecross section but only changing arch rib elastic modulus、the same lateral stiffness ofarch rib but only changing arch rib vertical stiffness、the same vertical stiffness of archrib but only changing arch rib lateral stiffness—are analyzed in aspect with dynamiccharacteristics rule，Changing arch&beam material strength grade of concrete and arch&beam cross section forms, overall stiffness of the whole bridge and the influence ofdynamic response under seismic action is researched.(3) Structure dynamic characteristics of corresponding design parameters under theconditions of same stiffness ratio is compared and analyzed, and reasonable scope ofdesign parameter is discussed，mainly including structure character response of5designparameters: different arch rib obliquity, lateral brace layout, rise-span ratio, derrickarrangement; side-middle span ratio, based on the natural vibration modal and structuremechanics response under seismic action, and the corresponding reasonable design scope are analyzed and proposed.