Analysis On Torsion Effect And Distortion Effect Of Extra-long-span UHPC Continuous Girder Bridge

Super-Long-Span Unidirectional Pre-stressed Ultra-High-Performance Concrete continuous box-girder bridge use the excellent tensile and compressive performance of UHPC. It’s a new continuous structure of Thin-walled dense diaphragms and partly externally prestressed. Compared with the traditional continuous girder bridge, spanning ability, light weight, strong stability, the late operation deflection of the bridge is small, easy to maintenance. But the thin-walled box girder because of bend torsion, warping deformation, distortion and other factors, its analysis of structure is more complex, therefore box girder structure analysis method has been constantly enriched and developed. About the box girder of large span, for the analysis of the effect of distortion, deeply concerned in recent years. Thin-walled box girder distortion effect as an important subject, is not allowing to neglect in the bridge structure design and analysis. Thin-walled box girder under the vertical eccentric load lead to bending and torsion, in order to prevent thin-walled box girder under eccentric load with rigid restraint torsional distortion phenomenon, in the design process, is often in the thin-walled box girder internal setting several diaphragm plate to reduce the distortion effect of box girder. For the UHPC models of thin-walled box girder bridge, this paper puts forward the dense transverse diaphragm arrangement. The author mainly conducted the following research work:(1) Box girder is discussed in this paper, by using the principle of energy method variable distortion of the differential equation for distortion Angle, load decomposition method was introduced in detail, discusses the distortion Angle and the deflection aberration of two different variables of the relationship between the differential equation of the interchangeability, comparison of the box girder distortion of the differential equation and differential equation of beam on elastic foundation similarity.(2) Design a UHPC double cantilever beam model, study the torsion and distortion performance of the cantilever beam of different diaphragm plate number. By comparison with the results making a research on the dense transverse diaphragm distortion stress and the action of vertical displacement. Test results show that the thin walled box girder integral torsional distortion resistance is strong, dense transverse diaphragm can improve the ability of cross-section torsion distortion increase in the number, when the diaphragm plate increased from three to four, torsional distortion stress reduced by 38% and the vertical displacement decreased by 42%.(3) Test beam finite element model is set up, numerical analysis of experimental beams, a more detailed investigation structure in terms of performance, in-depth analysis of transverse diaphragm effect the performance of the twist distortion, and compared with experimental results, the results show that the result is good. Combined with experimental results and finite element analysis, we can conclude that UHPC intensive diaphragm plate box girder torsional distortion resistance is strong, dense transverse diaphragm quantity can reduce torsional distortion parameters such as stress and distortion Angle. Using distortion Angle indicators to measure the size of the box girder distortion degree, the distortion Angle and horizontal clapboard volume indirectly reflects the ratio of the structure function and cost, a new type of box beam bridge transverse diaphragm spacing for 3 m, at the same time to consider the proportion of dense transverse diaphragm(control within 15% of the total weight) and the construction of the diaphragm plate spacing value range of convenient and better for 3 ~ 6m.