Study On Seismic Behavior Of Concrete Piers With Graded GFRP Bars

Bridge column is an important component of the bridge.Multiple earthquake damage investigations at home and abroad have shown that the pier damage is one of the main forms of damage.The destruction of the pier will cause deformation and even collapse of the bridge's superstructure,causing serious casualties and economic losses..Carrying out research on the earthquake resistance of concrete bridge piers is of great significance for ensuring the earthquake safety of bridges and the safety of people's lives and property.This article takes concrete bridge piers as the research object and innovatively proposes a new type of concrete pier with cascade configuration GFRP bars.The reinforcement of this bridge pier adapts to the bending moment distribution of the pier under the action of horizontal force.Decreased step by step,and a larger corner and deformation will occur in the section where the reinforcement changes when it is damaged,and it has a greater deformation capacity.Since there is no related research on cascade GFRP reinforced concrete bridge piers,this article based on the analysis of test results,combined with pushover test and numerical simulation methods,the seismic performance of concrete piers with cascade GFRP bars was studied,including the height of GFRP bars And the amount of use,the pushover pushover test of the pier,the ductility of the pier,the numerical analysis model of the pier pushover,the parameterized analysis,etc.The main work is as follows:1.Based on the GFRP bar and concrete and other material properties test,the Open Sees fiber element model of the pier pushover test is established,and the theoretical cascade reinforcement scheme of the GFRP bar concrete pier is demonstrated and designed numerically.2.In order to verify the feasibility of the stepped reinforcement scheme and study the influence of different section heights on the seismic performance of the pier,one reinforced concrete pier and four stepped GFRP reinforced concrete pier specimens were produced,and each stepped GFRP reinforced concrete specimen There are two cross-sectional changes.Taking the sample G650-1400 as an example,it indicates that the height of the two variable cross-sections from the pier bottom is 650 mm and 1400 mm.3.In order to evaluate the performance of the test piece,the pushover thrust loading test was carried out on the five test pieces under the condition of low axial force,and the data of the crack development,pier displacement and longitudinal strain of the pier were recorded.The development of cracks at the cross-section and the longitudinal reinforcement strain data evaluated the test results in terms of strength characteristics and ductility of the pier,and analyzed the effect of different GFRP reinforcement heights on the seismic performance of the pier.4.Combined with the shear force-displacement curve of each pier column,the crack width distribution curve along the pier height,the curvature and the corner distribution curve along the pier height,it reflects the bearing capacity,stiffness and deformability of the cascade GFRP concrete pier.5.Based on the experimental results of the Open Sees finite element platform and the five bridge pier specimens,a pushover numerical analysis model of the bridge pier specimens was established to simulate the stress performance of the cascade GFRP reinforced concrete bridge piers.The performances of reinforced concrete bridge piers,non-gradient GFRP reinforced concrete bridge piers and stepped GFRP reinforced concrete bridge piers are compared through the parameters of bearing capacity,stiffness,slenderness ratio,axial compression ratio and so on.