Research On Structural Performance For Steel-Concrete Hybrid Girder Rigid Frame Bridge

The steel-concrete hybrid beam continuous rigid frame bridge is a new type of beam bridge.It replaces a section of concrete box girder of the continuous rigid frame bridge with a steel box beam,and the concrete beam and the steel box beam are connected together at the structural level.The main beam portion of the continuous rigid frame bridge is formed.In this paper,with a continuous rigid frame bridge as the engineering support,the 42-meter-long concrete box girder of the continuous rigid frame bridge was replaced with a steel box girder.A steel-concrete hybrid beam continuous rigid frame bridge was designed and tested.For analysis,the main research contents include the following aspects:(1)Based on the finite element theory,the Midas Civil large-scale finite element software was used to establish the full-bridge unit model of the continuous rigid frame bridge,combined with the structural parameters of the existing steel-concrete hybrid beam continuous rigid frame bridge and the results of previous studies,the continuous The 42-meter-span concrete box girder of the mid-span rigid-construction bridge was replaced with a steel box girder to establish a full-bridge model of the steel-concrete composite beam continuous rigid-frame bridge,and the structure was checked for the bridge,which paves the way for subsequent calculation studies.(2)Based on the trial-designed composite beam continuous rigid frame bridge and analysis of its structural parameters,mainly including the effect of the dead load and live load,the ratio of the mid-span ratio and the length of the steel beam and the mid-span span.Comparison of Force Performance of Continuous Rigid Frame Bridge with Hybrid Beams.The results show that the mid-span bending moment decreases with the increase of the mid-span ratio,and decreases with the increase of the ratio of the length and the span of the steel beam under dead load;The maximum stress increases with the increase of the mid-span ratio,and decreases with the increase of the length of the steel beam and the ratio of the span.(3)Through the finite element model of continuous rigid frame bridge and composite beam continuous rigid frame bridge,the structural deformation and force characteristics of continuous rigid frame bridge and hybrid beam continuous rigid framebridge under typical static load conditions are analyzed and compared.The results of stress distribution and displacement show that the mid-span displacement and the bending moment at the top of the continuous rigid frame bridge of the hybrid girder under self-weight are smaller than that of the continuous rigid frame bridge.The displacement and stress of the continuous rigid frame bridge are more continuous than that of the continuous rigid frame bridge under live load.The bridge is slightly larger.(4)Comparing and analyzing the dynamic characteristics of continuous rigid frame bridges and composite beam continuous rigid frame bridges,and the dynamic performance of continuous rigid frame bridges and composite beam continuous rigid frame bridges with different pier height difference and different pier height parameters The results show that the first-order vibration modes of the continuous rigid frame bridge and the continuous rigid frame bridge of the composite girder are both system longitudinal floating,and the first-order natural vibration frequency of the continuous rigid frame bridge with hybrid girder is larger than that of the continuous rigid frame bridge;With the height difference and the height of the main pier increasing,the vibration frequency of the two bridges basically decreases,and the main pier height difference and the main pier height have great influence on the vibration modes of the two bridges.(5)Response spectrum analysis and linear time-history analysis of continuous rigid frame bridges and continuous beam bridges of hybrid beams were performed under the E1 earthquake.The calculation results were compared.The results show that the continuous rigid frame bridge and the hybrid beam are continuous The longitudinal displacement of the bridge is not much different;the lateral displacement of the continuous rigid frame bridge of the hybrid beam is greater than that of the continuous rigid frame bridge,and the difference increases gradually from the midspan of the side span to the middle span span,and reaches the maximum in the midspan span;hybrid beam The vertical displacement of the continuous rigid frame bridge in the middle span is smaller than that of the continuous rigid frame bridge.The internal force of the continuous rigid frame bridge of hybrid girder under earthquake is larger than that of the continuous rigid frame bridge.The internal force of the high pier top is smaller than that of the continuous rigid frame bridge,and the internal force of the bottom of the bridge pier is basically larger than that of the continuous rigid frame bridge.(6)By establishing a section restoring force model and using distribution hinges to analyze the elasto-plastic time-history response of continuous rigid frame bridges andcontinuous rigid frame bridges with E2 earthquake,the development model of the plastic hinges of bridge piers is obtained.The structure of the two bridges was evaluated for safety.The study shows that the continuous rigid frame bridge and the continuous rigid frame bridge with hybrid beam have no plastic hinges under the influence of 0.1 g seismic force and meet the requirement of seismic fortification.Under the action of the peak value of seismic wave 0.4g,both bridges have entered the yield state.In addition,the seismic responses of short piers of continuous rigid frame bridges with hybrid beams are larger than those of continuous rigid frame bridges.During the design,reinforcing bars should be reinforced locally at the pier tops and bottoms of piers,and the stirrups should be encrypted to increase their ductility.