Optimization Design And Long-term Performance Of BFRP Shell-concrete Composite Bridge Deck

In the bridge engineering community,there are major problems such as poor structural durability,severe corrosion of steel products,and lack of long-term performance.Fiber reinforced polymer(FRP)can be improved due to its superior properties such as light weight,high strength,fatigue resistance,and corrosion resistance.Resolving a series of problems brought about by traditional materials has become a new choice for bridge deck materials in bridge projects.Combining FRP profile with concrete,the research group developed a BFRP shell-concrete composite bridge deck structure that can give full play to their superior performance,namely the high corrosion resistance of the bottom BFRP profile and the compression resistance of the top concrete.Based on the previous research of the research group,this paper realizes that the overall stiffness and material utilization of the composite bridge deck structure still have room for improvement and long-term performance has not yet been effectively evaluated.Therefore,the following aspects have been studied:BFRP shell-concrete composite deck structure optimization design.After a preliminary optimization design,finite element analysis,alternative comparison and final optimization design,a new type of high performance BFRP shell-concrete composite bridge deck is proposed.Compared with the original model shell section of the research group,the utilization rate of the new BFRP formwork section material increased by 12.8%,and the overall stiffness of the combined bridge deck increased by 1.8 times.The new section has obvious advantages.The corresponding mechanical properties of the produced BFRP components were tested,and the actual tensile strength and elastic modulus of the BFRP shells were obtained.BFRP mold shell simulated concrete pouring test.The deflections and stress trends of different positions of BFRP shells during loading and unloading were analyzed,and the feasibility of using BFRP shells as construction templates without additional support was verified.Comparing with the stiffness of the original mold shell,it was found that the stiffness of the new mold shell section increased significantly.Static and long-term load-holding tests of BFRP shell-concrete composite bridge decks.Several sets of composite bridge decks were designed based on the changes in various parameters,and the static performance and stiffness changes of the composite deck slabs under the original shells and optimized shell types were compared and analyzed,and long-term load-holding tests up to 1000 hours were conducted.The test results show that the new BFRP shell-concrete composite deck has good overall performance and long-term stability.A three-stage deflection-time curve model for composite bridge decks is proposed.Numerical simulation of static and fatigue behavior of BFRP shell-concrete composite bridge decks.Using ANSYS software to simulate its static and fatigue properties,firstly the numerical simulation of the static performance of the three groups of specimens shows that the ultimate load and load displacement curves under the finite element simulation are close to the test results.Then,the fatigue life of the composite bridge deck is predicted and compared with the measured values.The fatigue life and fatigue S-N curves at different load levels are obtained.The fatigue life at any load level(or load amplitude)can be found by fitting a linear fatigue equation.