| With regard to bridge construction,problems such as the aging of the bridge due to environmental impact or disrepair,the increase in clearance height during the driving process,the coordination of traffic routes and the environment are now appearing more and more.In order to meet the requirements of use,many bridges in China need to be maintained or even dismantled and rebuilt.Demolition will result in a large amount of capital waste and other losses such as manpower and material resources,so bridge repair has become the main technical means.Synchronous jacking techniques are commonly used for some types of bridge repairs.The use of this technology can ensure smooth traffic or reduce the time of traffic interruption,replace or maintain the support to meet our scheduled clearance requirements,but also has the advantages of saving money and shortening the construction period.Synchronous jacking technology is becoming more and more widely used,but there are some safety risks for different bridge structures using different jacking schemes.Therefore,the simulation of beam bridges,especially box-type or continuous beam bridges,has a large theoretical study.And application meaning.This paper first describes the development of bridges at home and abroad,and then analyzes the causes of collapse of some bridges at home and abroad,and describes the bridges of different structural forms.The continuous beam bridge is also one of the beam bridges that are prone to damage.In this paper,the synchronous jacking of a four-span continuous beam bridge is taken as an example.The characteristics,main diseases and mechanism of the continuous beam bridge are introduced in detail.Combined with engineering examples,this paper introduces an overall synchronous jacking technology that is simple,fast,does not affect operation,ensures bridge structure safety,non-destructive construction,excellent cost performance,reliable quality,and can guarantee a relatively ideal operating state during the entire jacking process.Then use ANSYS software to build a three-dimensional model,apply forced displacement to carry out simulation and analysis,and test the advancement of the support of a row of rows,and then carry out the formal jacking,and get the result of the jacking of the bridge under different loads.Various results,as well as analysis of the impact on different spans,determine favorable jacking schemes from the listed operating conditions and avoid unfavorable scenarios.Guide the construction process to synchronize the jacking operation and safety monitoring under the stress and safety state,and improve the construction safety and efficiency.By comparing the data obtained from a four-span continuous beam bridge under several different working conditions,the top and the vertical rise can be concluded as follows:Try to rise 5mm height.It is found that the maximum tensile stress,the maximum compressive stress and the maximum deflection are the four conditions in the working condition,so the fourth row of bearings cannot be selected in the jacking position.Working condition 2 and working condition 4,due to the asymmetry of the load position,the bending moments near the bearing can not cancel each other,so the two kinds of working conditions will produce a large tensile stress,which is not conducive to jacking;the formal jacking is30 mm.The maximum tensile stress,maximum compressive stress and maximum deflection in working condition 1 are relatively small,but the working condition is still unfavorable.In the second working condition,the load arrangement in the first,second and fourth spans is also an unfavorable jacking scheme.In the third working condition,the load is arranged in the second and third spans,which is the most unfavorable position for jacking.During the jacking process,the position at which the maximum tensile stress is generated is at the standoff.The above-mentioned working condition 3 is the most unfavorable working condition in the listed working conditions,and the unfavorable factors of working condition2,working condition 4 and working condition 1 are sequentially weakened.During construction,the above conditions should be avoided as much as possible.Everything else is an option.In short,the bridge construction should focus on the transformation and maintenance of the bridge support.It is recommended to use the finite element method for the simulation analysis of the large-scale buildings such as bridges.Through numerical simulation,the most unfavorable lifting plan can be analyzed,and the favorable solution can be found.The hydraulic lifting system is adopted by the PLC hydraulic control system.Solve the safety problem of the upper structure of the bridge during the ascent and landing process,and ensure the safe construction and normal operation of the bridge.This paper studies the similar lifting technology for other buildings besides bridges. |
