Security Evaluation And Research Countermeasure Of Tall And Full Support In Girder Bridge Demolition

Affected by the East Gate bridge overpass planning,Nanshan interchange B,C ramp needs to be removed.B and C ramp belong to the city viaduct ramp bridge,high clearance.There are busy sidewalks and traffic line below the ramp.And some buildings were built below the main road near.Therefore,the ramp can be removed by the method of setting up a support.The height of the sppport is more than 30 m,so the risk of local and overall buckling caused by uneven stress is very great.Once the scaffold collapse,safety accident is immeasurable.In practical engineering field,Cast-in-site by set erection construction is very common.Before constructing the elastic plastic deformation of the foundation is eliminated by preimposed pressure on the support,and the strength,stiffness and stability of the support and the bearing capacity of the foundation can be tested.During the construction period,the weight of concrete is gradually loaded on the bracket.The speed and weight of the load is controllable.After the concrete pouring is completed,the support force is more uniform.But for the bridge demolition project,the load on the support during construction is abrupt.For example,when the main beam is cut off suddenly,the dead load of the main beam is applied to the support.It is difficult to control process and to ensure that the load of the bridge is uniformly applied to the support.Therefore,the erection of the support is the key position in the process of the bridge demolition.When we remove the continuous beam,the beam can bear part of the negative bending moment,the pressure on the support is less than the weight of the the upper structure.But when simple beams is removed,the weight of the upper structure is fully Acting on the support.Therefore,it is required to distinguish difference when we calculate the force.Based on engineering examples and according to the theory of finite element and structural stability,I simulated and analyzed the process of bridge demolition.and mainly did the following research:(1)evaluate the safety of the tall support;(2)put forward some construction measures to ensure the safety of the spport;(3)optimize the construction method in demolition project of simply supportedbeams and continuous beams and demonstrate the feasibility and advantages of the optimization scheme;(4)study on the stability of support assembled by universal members.