Study Of The Influence Of DCPCF In-plane Stiffness On The Dynamic Responses Of Building Structure

In recent years,the new building industrialization represented by precast concrete building structure has been promoted rapidly,and the construction level and quality have been improved significantly.Floor diaphragm not only can bear vertical loads,but also can transmit and distribute the horizontal seismic action.And the volume and cost of the floor diaphragm also occupy a large proportion in a building structure.Therefore,floor diaphragm is an important part of a building structure.At present,the laminated floor is one of the commonly used precast concrete monolithic floor.However,the cast-in-situ concrete layer has limited effect on improving the bearing capacity of the floor diaphragm,and it is not conducive to the full use of high-performance materials and innovative technologies.The untopped double-tee slabs floor with dry connection can meet the design requirements of modern floors with heavy loads and large spans,but its application in office and residential buildings is limited due to the uneven slab bottom and large structural height.Therefore,a new-type discretely connected precast concrete floor(DCPCF)system is proposed by our research group,and this system can be used to effectively solve the mentioned problems.However,DCPCF has limited inplane stiffness and cannot follow the rigid diaphragm assumption in the current codes for the structure seismic design.In this paper,the combination method of experimental research,numerical simulation and theoretical calculation is used to investigate the in-plane force mechanism of DCPCF,numerical simulation analysis of the seismic performance of building structures with DCPCF and the seismic design methods for DCPCF building structures.The main contents of the study are as follows:(1)The numerical simulation analysis method of DCPCF considering the connector restoring force model is proposed.Based on the experimental of DCPCF in-plane mechanical behavior and the theoretical calculation method of DCPCF in-plane deformation,the finite element program is used to establish the same finite element model as the test structure.And the static elastoplastic analysis is carried out.The comparison between the simulated results and experimental results shows that they are close to each other throughout the loading phase,which proves the accuracy of the numerical simulation method.(2)Based on the shaking table test of frame shear wall structure with DCPCF,the same numerical analysis model as the shaking table test structure is developed to investigate the seismic performance of DCPCF structure.The correctness of the numerical analysis method for DCPCF structures is verified.The same numerical analysis model as that of the test structure is established using a finite element analysis program based on the shaking table test of the frame-shear wall structure with DCPCF,and the correctness of the numerical analysis method for DCPCF structures is verified.In most cases,the test structure can meet the requirements of the code for inter-story drift ratio,indicating that the structure has good seismic performance.The acceleration amplification coefficient increases slowly with the increase of structure height,which indicates that the lateral stiffness of the lateral force resisting system is more uniformly distributed along the vertical direction.The diaphragm has undergone obvious in-plane deformation under horizontal seismic action.(3)Based on the shaking table test and validated DCPCF numerical analysis methods,the comparative analysis of full-scale DCPCF building structures and cast-insitu buildings is carried out.The finite element analysis program is used to establish the finite element analysis model of full-scale DCPCF structure and the cast-in-situ structure.The dynamic responses of the DCPCF structure and cast-in-situ structure are compared and analyzed under the dynamic elastic time-history analysis.The results show that the period of the DCPCF structure is higher than that of the cast-in-situ structure.In order to meet the requirement of greater than 90% for the vibration participation factor,more vibration patterns need to be considered in DCPCF structures.Compared with the cast-in-situ building structure,the internal force distribution in each lateral force resisting system under horizontal seismic action has changed significantly due to the DCPCF in-plane deformation.The horizontal seismic shear force borne by the DCPCF structural frame increases by 37.02% and the horizontal seismic shear force borne by the shear wall decreases by 37.88%.(4)Based on the finite element analysis model of the multi-storey and high-rise building with DCPCF,the influence of key parameters on the dynamic responses of the DCPCF building structure is revealed.The parametric analysis of the full-scale DCPCF building structure is carried out using a finite element analysis program,and the influence of parameters such as number of storeys,storey height,aspect ratio stiffness of joints and length of wall on the seismic responses of the DCPCF structure is investigated.It is demonstrated that the DCPCF building structure meets the requirements of the inter-story drift ratio in the code under different parameters.DCPCF structures can be designed as the rigid diaphragm for seismic design with the stiffness ratio coefficients between 12.17 and 30.81.Nevertheless,the seismic design method based on semi-rigid floor diaphragm has large error and safety risk in calculating the seismic shear force of building structure adopting DCPCF.Additionally,design suggestions for multi-storey and high-rise building structures using DCPCF are proposed based on the observed seismic responses.(5)The seismic analysis model of DCPCF structure considering the actual in-plane stiffness of the floor diaphragm is established to improve the seismic design method of building structure with DCPCF.Based on the seismic analysis model of "series-parallel multi-mass system",the mathematical analysis program is used to calculate the dynamic characteristics of the full-scale DCPCF structure.The theoretical values are compared with the simulated values.The results show that the period results of the theoretical calculation are close to those of the numerical simulation,which proves the accuracy of the theoretical calculation method of DCPCF equivalent beam model.The seismic responses of DCPCF structure under the action of 7 minor earthquake and Taft waves are calculated by the timehistory analysis.It is demonstrated that both of the results agree well with each other,which proves the accuracy of seismic analysis model of "series-parallel multi-mass system" used in the theoretical calculation.In addition,the horizontal seismic action and internal forces of DCPCF structure are calculated by the vibration model decomposition response spectrum method.The seismic design method of building structure with DCPCF is improved.The influence of DCPCF in-plane stiffness on the dynamic responses of building structure is investigated in this paper through experimental research,numerical simulation and theoretical analysis.The changes of frequency,acceleration,displacement,in-plane deformation,in-plane stiffness performance and internal force distribution of DCPCF structure under different parameters are analyzed.The seismic design method of DCPCF is improved.It offers a reference for the subsequent research on the seismic performance of building structures using DCPCF,and provides a foundation for the wider application of the DCPCF structure.