Research On Seismic Performance Of Green High-performance Fiber-reinforced Cementitious Composites Structure Using OpenSees

China is situated at the intersection of two major seismic zones in the world.80% of large and medium-sized cities are located in seismic zones.China is one of the countries with the most serious earthquake disasters in the world.Sometimes super-intense earthquakes occur.Generally,there is no warning when earthquakes occur.At present,human beings can not accurately predict earthquakes.The occurrence of earthquakes often causes heavy casualties and property losses,especially in earthquake-prone areas.In the region,earthquakes have caused tremendous impact on local social and economic life.Green High-performance Fiber-reinforced Cementitious Composites(GHPFRCC)is a new building material prepared by adding large amount of fly ash on the basis of ECC.This material has better ductility and energy dissipation capacity than ordinary concrete.The finite element software OpenSees(Open System for Earthquake Engineering Simulation)has open source code.It is very flexible in modeling function and defining model,and has strong practicability.It can fully display the mechanical performance of structure and provide a strong basis for engineering application.This paper mainly studies the following aspects:In the first part,the pseudo-static tests of C30 concrete frame columns and GHPFRCC frame columns under the conditions of non-fire,fire damage and post-fire reinforcement are mainly studied.The numerical simulation of the components is carried out by using OpenSees software,and the results are compared with the test results.Based on the validity of the model,the effects of axial compression ratio,reinforcement thickness,integral points and yield strength of steel bars on the seismic performance of GHPFRCC frame columns are studied.In the second part,the pseudo-static tests of C30 concrete frame and GHPFRCC frame under the conditions of non-fire,single-chamber fire and double-chamber fire are discussed and analyzed.The structure is numerically simulated by OpenSees software,and its hysteretic performance,energy dissipation capacity,ductility coefficient and stiffness degradation are studied.The simulation and test values are compared and analyzed.After verifying the validity of the model,the further exploration is made.The effects of axial compression ratio,yield strength of reinforcement and displacement size on the seismic performance of GHPFRCC frame are investigated.The main conclusions are as follows:(1)Under the same working conditions,the seismic performance of GHPFRCC frame structure is better than that of ordinary concrete frame structure.GHPFRCC materials can improve the bearing capacity and energy dissipation capacity of components or structures.(2)C30 adopts Concrete02 constitutive model,GHPFRCC uses ECC01 model and steel bar uses Steel02 to restrain concrete constitutive relationship.The established fiber model can simulate the hysteretic behavior of frame columns well,and the experimental results are in good agreement with the simulated values.(3)Comparing and analyzing the results of flexibility method and stiffness method,it can be seen that the flexibility method has smaller dividing elements,fuller hysteretic curve and slightly larger error with the test results,while the stiffness method divides the components into five elements,which has a higher coincidence with the test curves,so the stiffness method is used to simulate.(4)In the process of using OpenSees to simulate,the number of integrals does not change very much between 2 and 10,but too many or too few integrals will result in non-convergence of the results.When the number of integrals is selected as 5,the coincidence with the experimental curve is high.(5)The larger the axial compression ratio,the worse the bearing capacity of the structure.According to the current seismic design code,the limit displacement angle of frame columns is 1/50.Therefore,this paper suggests that the axial compression ratio of GHPFRCC frame columns should be between 0.21 and 0.7.The displacement ductility coefficient of frame structure is usually required to be greater than 3.This paper suggests that the axial compression ratio of GHPFRCC frame be controlled in the range of 0.15-0.5.(6)The greater the yield strength of steel bars,the better the energy dissipation capacity of frame columns.In this paper,it is suggested that the yield strength of steel bars should be measured in the simulation,and the simulation is in good agreement with the test.(7)Within a certain range,when GHPFRCC material is used for fire damage reinforcement,the larger the reinforcement thickness,the higher the bearing capacity and energy dissipation capacity of frame columns.When the thickness of GHPFRCC frame column is 30 mm after fire damage,it is the best.(8)The displacement size of GHPFRCC in the frame joint area affects the ductility of the structure.The larger the casting area of GHPFRCC around the joint,the greater the ductility of the structure.