Numerical Analysis And Construction Measures Of Setting Up Jointless Bridges In Shanxi Province

The jointless bridges cancel the expansion devices on the traditional bridges,which makes the bridge structure more integrated and improves the ride comfort.The maintenance costs of the bridges are lower during the entire life.There are only about 40 jointless bridges in China,and no jointless bridge has been built in Shanxi Province.At present,there are few studies on jointless bridges in Shanxi Province.The design and construction of jointless bridges are mostly based on experience.At present,there is no unified specification for jointless bridge construction.In order to study the feasibility of construction of jointless bridges in Shanxi Province,a 3×30m prestressed concrete continuous T-beam bridge was modeled as prototype and was modeled and analyzed by the bridge design software Midas Civil.Analyze the impact of key parameters on jointless bridges.The details are as follows:(1)By changing the boundary conditions and the structure of the abutment,three different jointless bridges are simulated,which are the integral bridge(beam and pier bearing connection),integral bridge(beam and pier rigid connection)and semi-integral bridge.The soil resistance and the pile-soil interaction are simulated by a series of Winkel soil springs,and the stiffness of the soil springs is calculated using the “m” method by the Chinese specification.Jointless bridges are greatly influenced by geological conditions,ambient temperature and humidity,and the ambient temperature and humidity are the average of the Shanxi multi-year index.(2)Three different jointless bridges were simulated under uniform temperature and temperature gradient condition.The results show that when the temperature rises,the maximum negative bending moment and the maximum positive bending moment occur at the 0# abutment section and 1# pier section of the two integral bridges respectively.The bending moment decreases from the abutment section to the middle section of the midspan,and temperature rising has a greater effect on the bending moment of the beam than temperature dropping.When the temperature is the same,the integral bridge(beam and pier rigid connection)has the largest bending moment of the beam,and the semi-integral bridge is the smallest.Under the influence of temperature gradient,the bending moments of the three kinds of jointless bridge beams gradually increase from the abutment section to the adjacent pier section and reach the maximum at the pier section,the bending moment of the midspan beam is almost constant.The temperature gradient will generate large bending moment in the beam,the influence of temperature gradient must be considered in the calculation of jointless bridges.(3)Modeling three different kinds of jointless bridges to analyze the influence of uniform temperature change on the vertical beam displacement DZ and the horizontal displacement DX of the pile head and the pier head.The results show that the effect of temperature dropping on the structure displacement is greater than the temperature rising.For the three kinds of jointless bridges,When the temperature drops,the maximum positive vertical beam displacement and the maximum negative vertical beam displacement of the integral bridge(beam and pier bearing connection)appear in the middle section of the sidepan and the middle section of the midepan respectively.The displacement of the integral bridge(beam and pier bearing connection)is the largest at the pile head,the displacement of the integral bridge(beam and pier rigid connection)at the pier head is the largest,and the displacement of the semi-integral bridge at each position is the smallest.(4)By combining the construction experience of various countries with the actual conditions in Shanxi Province,the effects of different bridge length,skew angle,abutment height,and soil around the pile on the longitudinal displacement and bending moment of the integral bridge abutment pile foundation were simulated.The parameter analysis shows that the increase of the bridge length will significantly increase the maximum displacement and bending moment of the pile.The skew angle of the integral bridge will cause the rotation of the beam end in the plane,and will also cause lateral pile displacement,Both the angle of the beam end and the pile head lateral displacement of will increase as the skew angle increases.When the skew angle is greater than 30°,the lateral pile displacement increases significantly.The abutment height and the soil around the pile have a great influence on the integral bridge.The greater the stiffness of the soil around the pile,the greater the pile head bending moment and the smaller the pile head displacement.(5)The design methods for abutment and abutment foundations under different geological conditions and uses are proposed,and the construction essentials of the jointless bridge and the suggestions for conservation in the later period are given.