| The bridge is an important part of the transportation line that crosses the geographical obstacles such as mountains,rivers and lakes.The continuous rigid frame bridge is widely used in practical engineering due to its convenient construction,strong spanning ability,reasonable force performance and good economic performance.Compared with land bridges,long-span continuous rigid frame bridges have complex environments and are subject to external loads such as earthquakes,waves,currents,ice floes,and winds throughout the life cycle.Once the damage occurs,it will cause losses and impacts on the economy and people’s livelihood.This paper studies the actual long-span continuous rigid frame bridge,and analyzes the structure dynamic response under the action of earthquake,wave and water flow through the vibration table test of the model.At the same time,the finite element model of the prototype structure of the long-span continuous rigid frame bridge is established for numerical analysis,and compared with the experimental results,then the displacement and internal force analysis of the structure under the action of seismic waves are carried out.The main contents are as follows:(1)Firstly,the vibration table test of structure is carried out to study the vibration characteristics and dynamic response of the bridge;obtain the first three frequencies of the structure in the presence of water and without water by processing the data.After comparison,it is concluded that the existence of water has some influence on the natural frequency of the low-order mode.(2)Analyze the test data to know that the acceleration response of the structure without water is larger than the response peak with water,and the largest acceleration response appears in the middle of the pier.Although the acceleration response of the structure is small when the wave acts alone,the acceleration response of the structure when the earthquake and the wave work together is greatly improved compared with the earthquake and the wave alone.(3)Numerical analysis of the prototype structure of the long-span continuous rigid frame bridge and comparison with the test results to verify the rationality of the model and test.The structural displacement and internal force response analysis was carried out using the prototype structural finite element model.(4)The numerical analysis of the prototype structure under earthquake and wave alone and combined action shows that the existence of water makes the displacement and internal force of the structure increase non-negligibly.The effect of wave action on the structure is related to the input wave element.When the frequency of the wave and the structure frequency are close,it will resonate with the structure,resulting in a larger structural response.The displacement and internal force response of the structure when the earthquake and the wave are combined are greater than the response of the earthquake and the wave alone,but it is not equal to the simple superposition of the two.When the waves and earthquakes that originally resonate with the structure act together,the seismic action will affect the wave field,resulting in a change in the original wave motion frequency,which in turn causes the structural response to be less than that of the wave alone.(5)From the perspective of probability,the method of calculating the maximum effect of the structure in the joint action of earthquake and wave is studied,and the example calculation is carried out according to the introduced theory. |
