Research On Sunshine Temperatur Field And Temperature Effects Of Long-Span Continuous Rigid Bridge

With the rapid development of economic and society, construction of long-span bridges, especially long-span prestressed concrete continuous rigid bridges,increases brilliantly. Due to poor thermal conductivity of the concrete structure, the structure itself will create non-linear temperature gradient. This non-linear distributed temperature gradient will have a considerable temperature deformation in the concrete bridge structure and cause thermal stress enough to make concrete structure crack. Temperature effects of the concrete structure is received more and more emphases in engineering.Based on Yuzha Jinsha River Bridge with the span of (99m+180m+99m), temperature field and temperature effects of the continuous rigid frame bridge were studied in this thesis. The main contents are as follows:(1)First the development state of the continuous rigid frame bridge was reviewed and the research profile of the temperature effects was described briefly.(2) The temperature effects theory and the provisions of national norms on temperature field were introduced briefly. We can see that temperature load patterns vary greatly because of the different geographical location and climate and environment in the different countries.(3)Box girder temperature field distribution was measured in construction stage and then box girder vertical temperature gradient function was fitted with the exponential function curve.(4)This thesis simulated and analyzed the stress and deformation of long-span continuous rigid bridge with the temperature gradient modes of the British bridge specification (BS-5400) and China General Code for Design of Highway Bridges and Culverts and field measurement results through beam element of MIDAS/Civil. Theoretical analysis results show that the cross-section displacement and temperature stress are all greater under three conditions. Especially the maximum displacement of the cross-section reaches-19.19mm and the tensile stress of the bottom of the cross-section reaches3.05MPa.(5)This thesis also established plate element model with MIDAS/Civil and entity-element model with MIDAS FEA to analyze local sunshine temperature effects using the measured temperature gradient mode. The results show that the plate element model that does not consider slab with haunched ribs of box girder causes large stress concentration. The entity-element model creates a principal stress up to1.15MPa under the bottom.(6)This thesis analyzed the stress and deformation of the full-bridge under the annual range of temperature loads which rises20℃. The results show that the annual temperature stress of the main bridge pier top and pier bottom section are larger because of the constraints of the superstructure and infrastructure in the annual range of temperature loads. This kind of loads will cause the longitudinal displacement of the superstructure and vertical displacement of the piers and not generate transverse direction displacement. Compared to sunshine temperature stress, the annual range of temperature stress is a little smaller.