Experimental Study On Flexural Behavior Of Continuous Decks Structure Connected With Bolts In Steel Simply Supported Beams

The simply-supported girder bridge with continuous slab-decks combines the advantages of the simply supported beam bridge and the continuous girder bridge,which can not only provide continuous lanes for vehicles,ensure driving comfort,but also maintain the static characteristics of simply supported girder bridges.At the same time,the continuous structure of the traditional simple supported girder bridge is complex,and the continuous structure of the bridge is located in the negative moment zone,and it is easy to crack in operation.Therefore,reducing the expansion joint and setting up the continuous structure of the bridge become the direction of the engineering field.In order to solve the above problems,based on the background of Hainan PuQian Sea-Crossing Bridge across the fault zone,and combining of steel and super toughness concrete STC(Super Toughness Concrete)lightweight composite bridge deck technology,this paper designed for two kind of simply-supported girder bridge with continuous slab-decks connected with bolts.For this structural form,not only the static performance but also the dynamic performance must be considered.This paper focuses on the static bending performance.To study the mechanical properties of this new structure and provide technical support for engineering applications,the full scale model test of negative bending moment and the finite element numerical simulation have been carried out successfully.On this basis,th e following contents are mainly carried out.(1)The design of two kinds of simply-supported girder bridge with continuous slab-decks connected with bolts: 1)The inverted T ribs were welded on the bottom of steel bridge deck and the side of diaphragm.Its height was equal to U ribs,and its transverse position and U ribs' position existed one to one correspondence.Inverted T ribs' web and flange were connected to the connecting plate;2)The height of the inverted T ribs were reduced,and they were welded to the top and end of the steel bridge deck.But the transverse position was welded to the adjacent U rib.The inverted T ribs' web connecting plates were canceled.(2)In order to find out the bearing capacity of simply supported variable deck continuous structures,the negative bending moment full-scale model tests for the above two schemes are carried out.The results show that the crack initiation of plan 2 is concentrated in the bolted connection zone,while the plan 1 bolt belt STC basically has no crack development.From the failure mode,the first one is U rib yielding,the bolt is not cut off;the second is bolt cutting,and the U rib is not yielding,whic h means that under the seismic load,the simply supported continuous deck structure will be damaged first,so as to protect the main structure of the steel box girder.(3)The ABAQUS finite element model of scheme 1 and scheme 2 was established,and the finite element simulation values agreed well with the experimental values.From the calculation results,the cracking stress of scheme 2 is 21.4MPa.It is slightly lower than that of scheme 1 which cracking stress is 22.2MPa.Then,the ANSYS integral finite element model of the two spans of the bridge across the fault zone in the Hainan PuQian Sea-Crossing Bridge was established.The tensile stress of STC layer under the lane load,vehicle load and temperature load was obtained.By comparison,both schemes can meet the requirements of serviceability limit state.However,the factor of safety against cracking of the STC layer in scheme 2 is higher than scheme 1.(4)In view of the inverted T ribs of scheme 2 are welded to the end plate,it has a certain effect on the diaphragms.Therefore,considering the opening of the diaphragms,the inverted T ribs can continuously pass through the diaphragms.This can avoid negative effects on diaphragms.At the same time,STC tensile stress is larger under local vehicle load through calculation.The reason for this is that the transverse spacing of inverted T ribs is too large.So the tensile stress of STC layer can be reduced by reducing the transverse spacing,which is less than the wheel load affected zone(0.6m ?0.2m).This can achieve the goal of scheme optimization.In this chapter,two design schemes are explained one by one.Through the ANSYS finite element calculation and the nonlinear finite element analysis of ABAQUS specimen models,the feasibility of the two schemes is explored.