Study On Safety Evaluation Method Of Steel Plateconcrete Composite Bridge Girders After Fire Exposure

Steel plate-concrete composite bridge girders can give full play to the mechanical properties of concrete and steel,have strong economic applicability,convenient manufacturing,meet the development needs of green building,and have been widely used in the field of bridge construction.However,with the increase of fuel carriers in recent years,the probability of bridge fuel fires due to accidents has increased significantly.After the fire,the high temperature will cause the rapid deterioration of the mechanical properties of concrete and steel,seriously weaken the carrying capacity of the bridge,and even cause the collapse of the steel plateconcrete composite bridge girders and other malignant accidents.Therefore,it is very timely and necessary to evaluate the safety status of steel plate-concrete composite bridge girders after fire.This paper studies the fire after series of superficial phenomenon and the test method of steel and concrete composite bridge girders,the building after the fire safety assessment method of steel and concrete composite bridge girders was established after the fire prediction models of carrying capacity of steel and concrete composite bridge girders is proposed after the fire safety of steel and concrete composite bridge girders fast evaluation method to calculate the condition.The main work is as follows:(1)The paper studies the apparent phenomena of concrete and steel after different fire temperatures and the corresponding series of detection methods,and puts forward the determination method of fire characteristic temperature of steel plate-concrete composite bridge girders.(2)Further study of the "highway bridge technique condition evaluation criteria"(JTG/T H21-2011)of the evaluation system,based on superficial phenomenon of concrete and steel building after the fire of steel and concrete composite beams component evaluation standard,put forward the security situation in steel and concrete composite beams after fire evaluation method,the overall structure of refining the steel and concrete composite beams,And the safety status rating of concrete bridge decks and steel plate beam members.(3)Selection of simply supported system as the research object,the steel and concrete composite beams reconstructed the concrete bridge panel and steel beam,respectively by the fire when two fire scenario database,the numerical prediction model was established,has carried on the comprehensive parametric analysis,reveals the different residual carrying capacity of steel and concrete composite beams under fire scenario and the attenuation law of redundancy,A method for calculating the residual bearing capacity of plate-concrete composite beams after fire is established,which takes the characteristic temperature of fire members and the proportion of fire area as state parameters,and the reduction coefficient of residual bearing capacity of plate-concrete composite beams after different fire scenarios is proposed.(4)The safety status of steel plate-concrete composite bridge girders is evaluated and calculated,and the safety status of concrete bridge deck members(5 classes),steel plateconcrete composite bridge girders(1 classes)and steel plate-concrete composite bridge girders(3 classes)are obtained.Based on the apparent phenomenon,the fire characteristic temperature of the plate-concrete composite bridge girders was deeply analyzed,the residual bearing capacity of the plate-concrete composite bridge girders after fire was calculated and its redundancy was analyzed,and the engineering application suggestions were given.