Out-of-plane Seismic Behavior Research Of Cast-in-situ Composite Infilled Wall With Metal Tailing Porous Concrete

With the continuous development of wall materials and pursuit of building energy efficiency,it is an inevitable trend to invent new type of walls to replace the traditional masonry infilled walls.Cast-in-situ composite infilled wall with the metal tailing porous concrete(MTPC composite wall)emerged in this context.MTPC composite wall possesses lower self-weight,thermal insulation efficiency,environmental protection and waste reuse,and it is of high popularization value.As the non-structural elements,infilled walls are usually ignored during the process of seismic design.However,the results obtained through the on-site observations after the earthquake motions have demonstrated that infilled walls usually exhibit out-of-plane(OP)failure,and it results in serious loss of life and property.Therefore,the OP seismic behavior of infilled walls has been widely concerned.In this paper,the OP seismic performance of MTPC composite wall is studied.The main research contents and conclusions are as follows:(1)Firstly,the dynamic mechanical properties of metal tailing porous concrete(MTPC)are studied by series of uniaxial compression and direct tension experiments with various strain rates.The experimental results show that the basic shape of the uniaxial compressive stress-strain curves of MTPC is similar under different strain rates.There is some oscillation near the peak of the curve,and the residual stress in the descending branch is high.The dimensionless curves can be described by the same expression.The basic shape of the uniaxial tensile stress-strain curves of MTPC is similar under different strain rates,and the tensile stress-strain curves of MTPC are similar to natural concrete.With the increase of strain rates,compressive and tensile strength and critical strain of MTPC increase.The tensile performance index is more sensitive to the change of strain rate than the compressive performance index.The compressive secant modulus increases as the strain rate increases,while the compressive and tensile initial tangent modulus of MTPC both remain unchanged at different loading rates.The dynamic increase factor(DIF)of each mechanical property parameter under different strain rates is fitted based on test data.By combining the DIF with the fitted expressions of dimensionless stress-strain curves obtained from the test,the dynamic compressive and tensile constitutive model of MTPC with different strain rates is established.(2)Quasi-static tests are conducted to investigate the OP mechanical behavior of MTPC composite wall.In order to simulate the OP horizontal uniform load caused by the inertia of the wall under the action of earthquake,the monotone load of the wall surface is carried out by the way of airbag inflation and expansion.The failure modes,OP resistance and deformation capacity of MTPC composite wall under horizontal uniform load are obtained by the test.The test results show that the MTPC composite wall has good integrity.The OP failure mechanism of MTPC composite wall is analyzed,the OP failure process of MTPC composite wall could be divided into three stages according to the change of boundary condition:the rigid connection stage which the wall is tightly coupled to the frame,the stage ranging from the plastic hinge produced at the boundary to cracking,and the short stage from cracking to collapse.Due to the constitution of the wall,the arching action in the last stage is limited.The ultimate load of the wall is close to the cracking load,for the sake of safety,cracking load is recommended as the bearing capacity of MTPC composite wall.Based on the wall specimen in the test,a finite element model is established,and its accuracy is verified.The test results are verified by the finite element analysis.Numerical simulation results reveal that the OP bearing capacity and initial stiffness of MTPC composite wall increase with the decrease of slenderness ratio or increase of the aspect ratio.The equivalent lateral force method is used to calculate the standard value of the horizontal seismic action of the wall.The results show that,no matter as the interior or exterior partitions,even MTPC composite wall is on the roof of the building,its OP resistance capacity still meets the seismic demand under the action of 9 degree rare earthquakes.(3)In order to further study the OP seismic behavior of the MTPC composite wall under the action of ground motion,the shaking table test is carried out on the full-scale wall specimens.Ground motions representing different types of sites are used as input excitation.The experimental results show that with the peak input seismic accelerations of shaking table ranging from 0.1g to 1.5g,the response of OP acceleration and relative displacement of each part of MTPC composite wall increase linearly.The natural vibration frequency of the wall specimen remains unchanged,no stiffness damage has occurred,and it is still in the elastic state.The sinusoidal wave matching with the natural vibration frequency of the wall specimen was used as the input excitation to carry out the resonance test and the test results were analyzed.Based on the proposed MTPC uniaxial dynamic compressive and tensile constitutive models,the finite element analysis model of the experimental wall is established.The dynamic response of the wall in time domain and frequency domain calculated by numerical simulation is in good agreement with the experimental results,which verifies the effectiveness and accuracy of the numerical method.The finite element analysis shows that the MTPC composite wall has better OP seismic performance than traditional masonry infilled wall.Finally,based on the calculation formula of horizontal seismic action given by the code and the calculation formula of the OP resistance capacity of MTPC composite wall derived in this paper,the OP seismic design procedure of MTPC composite wall is proposed.