Stability Analysis Of Prestressed Concertet Continuous Rigid Frame Bridge With Large Span

Continuous rigid frame bridge, as a form of the prestressed concrete box girder bridges, has been designed and constructed widely in domestic in recent decades. It has inherited many advantages of the continuous beam bridge and T-rigid frame bridge,such as:the continuous beam and bridge deck with fewer expansion joints,the fixed beam and pier top without supports,the construction without system conversion. So whether in aspect of the difficulty of construction or in aspect of the behavior in usage period,continuous rigid frame bridge has a better performance than other similar bridges.Survey data shows that in the design of continuous rigid frame bridge, people don’t pay enough attention to the stability issues of bridge structure, which leds to loss due to instability of bridge bearing capacity and the bridges that not damaged by instability issues select the larger stability safety coefficient to cover up the defects of the stability characteristic values calculation. With the extensive construction of continuous rigid frame bridge, its span, pier highth and bridge longth have a growing trend and so bridge stability issues that the one of the key technical problems are particularly important. The main research contents of this paper can be divided into the following several points:In this paper, the completion pier’s critical stability coefficient and buckling modes of autologous under the bridge self-weight and wind loads are in detail analyzed.During the bridge construction, in cantilever casting of t-shaped frame’s the largest cantilever and under the different load combinations (such as self-weight, hanging basket with accidental fall), the influence on stability of t-shaped structure has been in detail analyzed;The using continuous rigid frame bridge’s stable critical factor and buckling modes under the vehicle and the crowd load are in detail analyzed;In this paper, the continuous rigid frame bridge’s stability of differences in the construction phase and the operational phase are in detail analysised, and the reasons for the existence of the differences are all found.Through research and analysis, it cames to the following conclusion:Wind loads are less affected on the bridge stability factor,because pier axial force caused by the wind loads is small;Uneven weight and hanging basket with accidental fall are a major factor affecting stability. When the bridge is building,we should focus on controlling the progress of the anchoring of hanging basket and concrete pouring. The most unfavorable stages of the construction phase is the largest cantilever stage for the bridge stable state and this stage can serve as a bridge to stability control during construction phase;In the operational phase of the bridge, the stability factor of bridge under live load is the minimum.So this phase can be used as foll-bridge stability control phase;The closure would make the piers of the bridge improves the stability and the bridge system conversion will make the reduced stability of pier.Through the above analysis, the author comprehensively understanded the stability at different stages of the long-span continuous rigid frame bridge and mastered the FEM calculation method of bridge stability.