Research On Seismic Behavior And Direct Displacement-based Design Method Of Precast Composite Wall Structure

As a new building structure system,precast composite wall structure has many advantages,such as ecological,environmental,energy saving,energy dissipation and building quickly.The infilled block material of precast wall has many choices,which are plant fiber raw soil base block,recycled EPS lightweight aggregate concrete block,cotton stalks block according to local conditions.The ribbed-frame material of precast wall can use steel fiber reinforced recycled concrete or fiber reinforced recycled coarse aggregate concrete materials which has higher strength and meet with the national environmental protection policy and the demand of national strategy of sustainable development.The application of prefabricated composite wallboard and the composite floor slab improves the overall rate of precast fabricated composite wall structure,speed up the “construction industrialization,housing industrialization” process.In precast composite structures,precast wallboard material configuration design and the application of prefabricated boundary connection technology is the key issues of rapid development and popularization application.At the same time,the structure design method based on performance were focused primarily on frame structure and shear wall structure,and few studies for bending-shear type precast composite wall structure performance design method based on direct displacement.Based on the precast composite wall structure,this paper prepares to solve the above key problems at three different scale space launches of materials,components and structure.On the basis of previous research,the following researches in this paper were carried out.(1)Preparation and research on basic mechanical properties of fiber reinforced recycled concreteUsing recycled coarse aggregate and recycled fine aggregate instead of natural sand,stone,respectively,incorporating fiber to improve the concrete performance,two kinds of fiber reinforced recycled concrete materials have high strength and ductility of material are configured as substitute for natural concrete of precast composite wallboard.Through the orthogonal experiment,the sensitivity of the key factors on the strength of materials are analyzed and the optimal mixing proportions of the two kinds of fiber reinforced recycled concrete material are obtained.the two key factors,which are recycled coarse aggregate proportion and recycled fine aggregate,are studied through single factor experiment respectively,and combined with the physical properties of recycled aggregate,the effect of different basic mechanics performance index are studied,and the constitutive equation and key parameters are confirmed.Based on Weibull distribution theory and the principle of equivalent strain assumption,the statistical damage constitutive model of fiber recycled fine aggregate concrete was derived,and through the regression fitting the shape parameter and scale parameter are presented with substitution rate of recycled fine aggregate,furthermore the damage evolution law of recycled fine aggregate concrete with different substitution rate of fine aggregate is analyzed.The above research is the basis for the application of fiber reinforced recycled concrete in the assembled composite wall structure.(2)Experiment study and analysis on the seismic behavior of precast composite wallA new boundary connection form of precast composite wall is put forward,of which the vertical reinforced connects through embedded welding plate,and horizontal set the horse tooth form joint between wall panel and cast-in-place edge component.Six precast composite wall specimens under low cyclic loading were tested and the seismic performance of different vertical edge component reinforcement,different ribbed frame materials and different infilled block material are analyzed.The results show that,the failure process shows a "infilled block-ribbed frame-vertical edge component" mode,and specimens have a good work performance,each part of specimens give full play to their respective role,present the good performance of energy dissipation.At the stage of damage,the welding plate welding are basically intact,which can not only transmit reinforced vertical stress effectively,but also work good with the bottom beam;using the recycled coarse aggregate concrete and recycled fine aggregate concrete as ribbed-frame material,the two specimen shows different seismic performance indexes compared with ordinary concrete ribbed-frame wall,the bearing capacity declined slightly,but the ductility and energy dissipation are improved,in one word,the comprehensive performance of specimens are good and can be used in the precast composite wall structure.With the increase of the vertical edge reinforcement ratio,the initial component stiffness increased,the late strength degradation flat relatively,but the increase of the reinforcement will cause extent bending shape deformation of the wall.Using fiber reinforced EPS concrete as infilled block results in an increase of insulation advantages,ductility and energy dissipation the wall,except a slightly reduce of bearing capacity.(3)Shear bearing capacity and influence factor analysis of precast composite wallA three-dimensional finite element model of precast composite wall is built by using ABAQUS software,and the validation between the models under static loading elastoplastic analysis and corresponding test component are carried out.On this basis,through the parameter analysis of block strength,frame structure material strength,ribbed-frame material strength and axial compression ratio,the influence of each parameter are studied.According to the shortcomings of four ribs column vertical welding plate in the test,the vertical wall boundary connection is optimized and improved.Based on the experimental research and numerical analysis,the failure mechanism of the precast composite wall was analyzed;using the cross shear pin bolt mechanism of the interface to consider embedded welding plate welding connection on the shear strength of the wall,combining with shear wall shear bearing capacity model of the theory,and through the key parameter influence analysis,the contribution of the components to the overall shear bearing capacity are organized and a shear bearing capacity formula suitable for welding plate vertical connection are given provide theory support for the practical engineering design and calculation.(4)Research on damage model and damage limit performance indicators of precast composite wall structureOn the basis of experimental study of precast composite wall,the damage development characteristics are analyzed in the points of crack propagation and energy dissipation.Combining with the damage development characteristics of precast composite wall,the damage displacement beyond threshold of the existing models is improved,and an improved P-A-M damage model suitable for precast composite wall is given.The comparing verification of different damage models shows that the improved P-A-M damage model conforms hysteretic energy dissipation trend of the precast composite wall and has good convergence,which can reflect the damage development process and its characteristics ofprecast composite wall.On this basis,using the proportion of hysteretic energy dissipation on total energy consumption as a reasonable weight coefficient to reflect the components' damage to the structure damage;using weighted coefficient method to establish the whole structure damage model,in which the damage layer weight coefficient comprehensively consider the effect of structure layer damage and height,and has clear concept and physical meaning to describe the evolution of structure damage behavior more accurately.On the basis of a comprehension on above study and other related research results,this paper gives the damage degree and the corresponding damage index range of the precast composite wall structure to determine the structure lateral displacement mode in the design of performance based seismic design.(5)Direct displacement based design method of precast composite wall structureAccording to the action of stress and deformation characteristics analysis of bending shear type precast composite wall structure under horizontal earthquake,the structure elastic lateral deformation curve are obtained by using the Hamilton principle and functional variational theory.Using the story drift angle as indicators,combined the structure theoretical framework with the unique three anti-seismic line of precast composite wall structure,the performance level of the structure is quantified.By introducing damage coefficient,the lateral displacement mode of precast composite wall structure under the performance level are determined,and though the equivalent single degree of freedom system and displacement response spectrum,the direct displacement based design method is finally proposed.By a design example,the method is verified,and results show that the method proposed in this paper is reasonable and effective,which can provide a reference for this kind of structure in the practical engineering application.