Experimental Study And Theoretical Analysis On Strengthening RC Girder Bridge With Steel Wire Mesh And Polymer Mortar

A new strengthening technology with high strength stainless steel wire mesh and permeability polymer mortar has been gradually used in the domain to reinforce concrete in recent years. This dissertation regards Dongguan Bridge as engineering background and focuses on the systemic experiments and theoretical analysis on behavior of strengthened RC structures with high strength stainless steel wire mesh and permeability polymer mortar. The main research contents and achievements can be summed up in the following aspects.1. Based on the test of 243 axial tensile adhesive strengths, 24 shear adhesive strengths, and 9 debonding strengths, the bond behavior between polymer mortar and concrete was studied and its influencing factors were analyzed. The main influencing factors include four aspects. The first is plastering age, the second is interface roughness, the next is the strength of concrete and mortar, the last is position of the repaired interface. Their significance level from high to low arranges according to this order. Furthermore, there is an effective length of reinforcing layer, which is extremely remarkable to the bond strength. At the same time, axial tensile adhesive strength models, shear adhesive strength models, bond strength models are proposed. Combined finite element analysis, the bond-slip models are proposed and validated. The bonding anchorage performance of stainless steel wire mesh and polymer mortar was also analyzed, and their bond strength models and the anchorage length models are proposed. At last, the points for attention in reinforcement construction were given.2. Based on the experimental study on strengthening performance of beams with high strength stainless steel wire mesh and permeability polymer mortar and on bond behavior between polymer mortar and concrete, the failure models of strengthened beams were analyzed. The debonding failure mechanism of the reinforcing plate is principally explored. In view of the debonding failure zone, the concept of debonding failure plate is educed. Based on the debonding failure plate, the analytic solutions of shear stress and normal stress are deduced, which is at the end of reinforcing plate of flexural member, and its failure criterions are also proposed. The simplified formulae of debonding strength are deduced at the end of reinforcing plate. Based on the debonding failure plate, the formulae of debonding strength and its failure criterions are also deduced, which failed because of the mid-span bending cracks. At the same time, based on the shear behavior of strengthened beams and finite element analysis, the formulae of shear debonding strength are proposed.3. Based on the experimental study on 14 beams and the finite element analysis on 26 beams, which were strengthened with high strength stainless steel wire mesh and permeability polymer mortar, the influencing factors of reinforcing performance were analyzed, such as concrete strength, reinforcement ratio of the old members, stirrup ratio of the old members, secondary loading, shear span ratio, strengthening modes, the amount of stainless steel wire mesh. Combined the study on bond mechanism and debonding failure, the design formulae of flexural load-carrying capacity, shear load-carrying capacity,flexural stiffness, shear stiffness, maximum crack width, maximum diagonal crack width and the maximal ratio of reinforcement are proposed. And now, the calculation system of strengthened RC beams is founded. Furthermore, the calculation results are in good agreement with the interrelated tests.4. In order to know the strengthening performance of Dongguan Bridge with high strength stainless steel wire mesh and permeability polymer mortar, this dissertation focuses on the static load tests before and after the installation of the strengthening system. Making use of others traffic investigation, the program of VLS, vehicle load spectrum, is written, and stochastic vehicle load spectrums in different traffic conditions are constructed. By using ANSYS, a familiar finite element program, the bridge's space dynamic response under stochastic vehicle load spectrums is analyzed, which provides a method for analyzing dynamic performance and fatigue performance of highway bridges under stochastic vehicle load spectrums. The results farther show that the calculation system is correct and the strengthened bridge has good dynamic performance and static performance. Under dynamic loads, the most dangerous load is two-lane non-symmetric vehicle load spectrum in uniform direction. The transverse vibration of the medium and small span highway RC bridges is weak, and train flow direction has a weak effect to the bridge's vibration. Because of strengthening, the bridge's maximum displacement reduces 14.97%, and its fundamental frequency increases 6.94%. The whole bridge's stiffness and its carrying capacity are greatly improved, and the strengthening effect is significant. The bridge's dynamic deflection under vehicle load spectrum is less than its static deflection under the load of China specification of HS-20.