Temperature Distribution And Effect Research On Steel-truss Beam Bridge Deck System During Asphalt Paving

The steel-truss beam bridge deck system is a kind of statically indeterminate structure system with dense steel bearings,and its restraint and stress relationship are very complicated.When paving high-temperature asphalt concrete on it,the inhomogeneous temperature field will lead to a large temperature effect in the bridge deck system and bring about large displacement and reaction force to the bearings,which will have a negative impact on the safety of the structure.At this stage,there is less concern about the temperature effect caused by high temperature asphalt paving in such structures.In particular,the laws of displacement and reaction force of the bearings are to be studied.In order to carry out the bearings design and asphalt paving construction reasonably,to ensure the structural safety during construction,the temperature field and temperature effect of the steel truss bridge deck system under high temperature asphalt paving are studied,the law of the spatio-temporal distribution of temperature and mechanical response of bridge deck system are revealed.Firstly,the initial and boundary conditions for calculating paving temperature field are determined from the condition of definite solution to the transient temperature field function.A three-dimensional temperature field model of steel truss bridge deck system is established.The dynamic paving process is simulated by life-death element method,and the spatio-temporal distribution law of temperature field on bridge deck system is analyzed.The results show that the paving center rises to the highest temperature 720 s after the paver reached,and the influence of asphalt paving on the temperature of steel-truss bridge deck system is within the vertical depth of 0.45 m.The temperature of a certain point in the transverse direction of bridge deck is not only related to its transverse coordinates,but also to the type of its location.The maximum transverse temperature gradient occurs in the range of 0.26 m around the paving edge.Longitudinal temperature distribution exhibits obvious time lag.Secondly,by adjusting the parameters of the model,the influence of different environmental conditions and paving methods on the temperature field are studied.The results show that the pavement material and paving width have the greatest influence on the temperature field,and the construction season has a greater impact,and the wind speed has less impact.The exponential and triangular functions with multiple undetermined coefficients can be used to fit the most unfavorable vertical and transverse temperature load,respectively.Finally,a three-dimensional mechanical model of the steel-truss beam bridge deck system is established,the change of boundary conditions are simulated by changing the sliding constraints of steel bearings.Three different sections are set up,the mechanical response of the bridge deck system is studied under the most adverse temperature load.The results show that the steel deck and U rib are mainly subjected to longitudinal stress,while the diaphragm beam is mainly subjected to transverse stress.There are obvious rules between the distribution of displacement and reaction force in all directions of the bearings and the paving position.At different sections,the variation of longitudinal support reaction force is the largest,and higher grade bearings should be adopted at the places where displacement and reaction force are the largest.The research results provide a theoretical basis for the design of bearings of steel-truss beam bridge deck system and the scheme of asphalt concrete paving construction.