Abstract:The infilled RC frame, one of the most common structural systems, is applied widely, but there is no rational method for analysis and design to evaluate the seismic-resistant ability due to the complicated interaction between the frames and walls. Many studies on the interaction between frames and walls and the performance of infilled RC frames were performed based on the experimental study and finite element analysis, and a variety of simplified models were proposed in the past few decades, which are capable for the overall seismic response analysis. The research status of seismic performance of infilled RC frames was discussed from the following aspects: in-plane behavior, out-of-plane stability, and seismic retrofitted infilled RC frames. The latest research progress is presented, the existing problems are pointed out, and the research trend is prospected.

Abstract:To reveal wind pressure spectra and establishes the energy spectrum, vortex movement or the evolution of the relationship between turbulence scales, the wind tunnel experiments were performed which focused on the vortex axis direction and cross wind direction measuring points. Wind pressure distribution and the vortex axis motion characteristics of square flat roof surface were investigated when the flow was not perpendicular to the windward wall with different flow condition (uniform, grid-generated turbulence and the terrain B) and different wind direction (15°, 30° and 45°) through the rigid model wind tunnel pressure tests. Results show that the maximum wind suction appears near the windward point of lower triangular area with three different flow conditions. The peak mean and rms pressure coefficient reach the maximum at 30° wind direction. For the same incoming flow condition, the angle between the vortex axis and the leading edge of the windward direction and the range of reattachment are gradually decreasing as the wind angle increases. The peak value of the wind pressure spectrum near the windward point with the vortex axis direction is proportional to the corresponding roof wind suction. In the high frequency range, the measured wind pressure spectrum response frequency is corresponding to the peak spectral energy, also with the greater the average wind suction. In the low frequency range, the corresponding frequency is corresponding to the spectral energy peak, also with the greater the pulsating wind suction. The correlation between the measuring points in vortex axis direction with uniform flow condition is poor, and cross spectrum is the exponential decay mode with grid-generated turbulence and terrain B flow condition.

Abstract:A remarkable non-Gaussian distribution of local acceleration responses of the cooling tower is indicated through field measured data analysis, and extreme estimation method based on Gaussian assumption of wind-induced responses are not fully applicable. To study the extreme considering non-Gaussian characteristics, a 179 m high large cooling tower in northwest was selected, and acceleration vibration signals at representative positions of the tower were obtained under ambient excitation. The vibration signals were preprocessed combining random decrement technique and natural excitation technique. Three pattern recognition methods (ARMA, ITD and STD) were applied to analyze the frequencies and damping ratios for the first ten order modes, and comparison between measured values and the finite element calculation were carried out. Following modal combination, equivalent synthetic damping ratio of the cooling tower was derived. The peak factors and acceleration response extreme of samples were calculated by two kinds of extreme estimation methods (peak factor method and Sadek-Simiu method), and a single value of the measured response was given. The wind-induced response analysis was carried out under the measured damping ratio 2% and the standard damping ratio 5% based on the total transient time domain method, and error analysis between measured values and the finite element calculation was carried out. The comparative study shows that the results of the measured and finite element analysis are consistent with the results of the first 10 frequencies, with the maximum difference of 9%. The maximum difference between the measured acceleration responses of the two extreme estimation methods is 32.02%, and local points of wind vibration response extreme of finite element under measured damping ratio and the measured extreme are consistent.

Abstract:To study the wind-induced destroy mechanism and improve the wind-resistance design for outdoor large single-column billboards, two kinds of wind tunnel experiments were conducted on a typical two-plate billboard. Based on synchronous pressure measurement test, the coefficients of horizontal force that is parallel to and perpendicular to plate, and torque loads coefficients in different wind directions were investigated, the wind pressure distribution along width of board and wind force coefficient of structure at most unfavorable wind directions were diagramed, and the analytic power spectrums density (PSD) of the horizontal and torsional wind loads were given. According to the aero-elastic model test by utilizing high frequency force balance (HFFB), the wind-induced force responses at the bottom of the two-plate billboard with flexible column were analyzed. The theoretical methods that calculate billboard's wind-induced dynamic responses in horizontal and torsional directions were proposed based on the analysis of experiments. The results indicate that the PSD of wind loading which is perpendicular to plate needs to take aerodynamic admittance function into consideration. The excitation from turbulence and vortex shedding are the main contribution to torsional load spectrum. The aerodynamic damping in two directions (i.e. perpendicular to plate and torsion) has a significant influence on wind-induced vibration of billboard. The theoretical approach is validated through the wind tunnel experiment, and it can be applied in predication for wind load effect on billboards.

Abstract:The selection of current cooling tower group is mainly based on load interference factor, which it is difficult to truly reflect the force characteristics of the cooling towers group. To study the four-tower combination optimization scheme based on the static wind response target and combined stress performance of super-large cooling tower in different four towers combinations, with the under-construction of the world's highest cooling tower(220 m) as the engineering background, the synchronous rigid body pressure measurement by wind tunnel tests were respectively carried out for five typical four towers combined cooling tower groups, including tandem, rectangular, rhombus, L-shaped and oblique L-shaped, totally having 320 working conditions. The surface wind pressure distribution pattern of cooling towers under different four tower combinations was obtained, and an integrated simulation model of "tower barrel-stanchion-ring foundation" was established based on the finite element method. The static wind responses of super-large cooling towers under three dimensional asymmetrical wind loads were analyzed respectively for different combinations, currents, wind directions and relative positions of towers, in which the influence law of four tower interference on the force and displacement response of the cooling tower under seven typical response targets was discussed. The influence degree and distribution law of different static response indexes were studied. Based on the static wind response target, the optimal scheme of the combination of four towers was given qualitatively. The results show that wind-resistant performance of the tandem layout is optimal, and the wind-resistant performance of the rhombic, oblique L-shaped, rectangular and L-shaped layouts are gradually reduced.

Abstract:To study the seismic behaviors of full-scale steel reinforced recycled concrete columns under high axial compression ratio, the columns with three types of recycled coarse aggregate replacement rate under different axial compression ratios were designed, and four specimens were experimented on the 40 000 kN multi-function testing machine under low cyclic reversed loading.The influences of different design variables on horizontal load bearing capacity, hysteretic behavior, skeleton curves, energy dissipation, deformation and stiffness degradation of specimens were obtained after observing the mechanical processes and failure patterns. The results show that the ultimate failure pattern of the four specimens is the bending-shear failure and the hysteresis loop of each column is relatively plump, indicating that the columns show good energy dissipation behavior.The increase of the recycled coarse aggregate replacement rate decreases the deformability, but it has little influence on the bearing capacity and stiffness degradation of the specimens.With the increase of axial compression ratio, the load-bearing capacity, stiffness and energy dissipation behavior of specimens raise, but the stiffness and bearing capacity degradation intensifies and the ductility declines acutely. The steel reinforced recycled concrete columns with high axial compression ratio can still maintain good seismic performance, and this study provides the basis for subsequent theoretical research and practical engineering application.

Abstract:To study the influence of openings on the seismic behavior, two 1/2 scale, two story and one bay models were designed. There are doors on the one side for one model and windows symmetrically for the other. Based on the low-reversed cyclic loading test, the failure characteristics, hysteretic behavior, skeleton curves, bearing capacity, stiffness, energy dissipation and ductility were analyzed. The wall on the one side without openings was damaged along the edge of the beam and column, while the wall on the other side was damaged above the doors and on the corner. The wall between windows and the corner wall were damaged for the model with windows. The bearing capacity on the one side without openings was higher 27% than the other side with doors. The initial, yield and peak stiffness on the one side without openings were higher 7.37%, 30.43%, 35.97% respectively than the other side. The positive and negative ductility of the model with symmetry windows openings were higher 39.55 % and 41.86 % respectively than the other model. The results show that single row of steel bar shear wall is the first seismic fortification line and frame with stability load carrying capacity can function as the second seismic resistant system. For the frame, the design principle of "strong column and weak beam", "strong shear and weak bending", and "strong node" are realized.

Abstract:To investigate the seismic performance and deformation index limits, twelve T-shaped reinforced concrete (RC) shear walls with different shear span ratios, design axial compression ratios and longitudinal reinforcement ratios of boundary element were designed according to Chinese current codes. The specimens were tested under low frequency cyclic loading to study the seismic behaviors such as failure pattern, hysteretic characteristic, energy dissipation capacity and deformation capacity. According to the test results, corresponding deformation index limits of six performance states were obtained with two methods based on skeleton curve and experimental phenomena. Regression analysis was conducted with collected experimental results to build the correlations of deformation index limits at different performance states and shear span ratios, design axial compression ratios and longitudinal reinforcement ratios of boundary element. The results show that the failure patterns of specimens are transformed from flexural failure to flexural-shear failure with the decrease of shear span ratio. It is reasonable and feasible to establish the relationship between deformation index limits and damage extents of T-shaped RC shear walls based on skeleton curve. While the deformation index limit has positive correlations with shear span ratio and longitudinal reinforcement ratio of boundary element, there is a negative correlation between deformation index limit and design axial compression ratio.

Abstract:To investigate the seismic performance of unbonded fabricated frame, a numerical model of the beam-column connection was built in OpenSEES. The comparison between test results and numerical analysis proved the effectiveness of the numerical model. Eighteen different ground motions were employed in the seismic fragility analysis according to the site conditions. The maximum story drift and tensile force in prestress strands were chosen as the damage indexes. Through IDA analysis for two 6-story frame structures, i.e. the common RC frame and unbonded fabricated frame, the IDA curves and fragility curves were obtained. According to the analysis, the unbonded fabricated frame can sustain ground motion record with smaller intensity index than the common RC frame with the same configurations, i.e. the cross-section of column, reinforcement ratio etc. Under small earthquake, the two frame structures present similar performance, while under strong earthquake, the collapse resistance performance of common RC frame is better than that of the unbounded fabricated frame.

Abstract:To study the relevant laws of high vacuum dewatering in low permeability soil and improve the efficiency of dewatering, the finite difference software FLAC3D was used to simulate the dewatering process of high vacuum well under various working conditions including different time, different vacuum degree, different well depth and different distance of the two wells, mainly focusing on the amount of discharge and the pore water pressure. According to the amount of total discharge and the distribution of pore water pressure under different distance of the two wells, suggestion of the reasonable distance of the two wells was given based on the soil profile of Ningbo metro Yinghua Station. It concludes that the low permeability soil is relatively difficult to dewater, but with the increase of the vacuum and the depth of the well, the amount of water pumped out of the low permeability soil increases. The vacuum negative pressure in the low permeability clay passes faster above the water level and the transmission speed is limited below the water level. High vacuum dewatering well has good applicability in low permeability soil layer.

Abstract:To describe nonlinear shear rheological properties and establish shear rheological model for soft clay, the shear creep experiential formula suggested by Singh-Mitchell was modified to be valid in low corrected stress level condition. The functional expression of viscoplastic shear strain rate in terms of shear stress and viscoplastic shear strain was derived from the relationship equation among viscoplastic shear strain, dissipative shear stress and equivalent time. After combining this expression with shear elastic model, a shear elasto-viscoplastic model was formulated. Based on this model, analytical solutions of shear rheology were not only obtained for single-stage and multi-stage loading under constant effective confining stress, but integral solution of shear rheology was also obtained for both effective confining and shear stresses to vary with time. The results show that the rheological model can numerically simulate relatively well the shear creep development under multi-stages loading in drained triaxial test, and describe the rheological rules that shear strain changes with effect factors such as corrected stress level (or shear stress), effective confining stress and loading duration.

Abstract:To select ideal type and content of soil conditioner in clay formation, the Atterberg limits of clay were measured. The applicability of soil conditioners was determined and the effects of dispersant on different clays were compared by analyzing the influence of soil conditioners on the clays. The Zeta potentials with different dispersant contents and repulsive energy among particles were also measured to analyze action mechanism of the dispersants. The results show that it is difficult to achieve ideal effect only by using anionic-cationic foam individually. The flocculant increases the liquid limit and plasticity index of the bentonite, so it also contributes to the increase of the shear strength. In the contrary, the dispersant decreases the liquid limit and plasticity index of the clay, thus it can decrease the shear strength, which makes the dispersant more suitable for clay conditioning. Compared with kaolin, the mixture (the mass ratio of bentonite to kaolin is 1:1) and bentonite require much time and dispersant due to high content of bonding water in bentonite. The effect of dispersant keeps unchanged after the injection ratio of dispersant reaching a certain value. With the increase in dispersant content, the Zeta potential decreases (i.e., negative charge increased) and tends to a lower constant in bentonite, kaolin and their mixture. The mean barrier potential V_max/R of clayey particles get higher with more dispersant, thus it is more difficult for the clays to be agglomerated and easier to disperse.

Abstract:To study mechanical properties of frozen saturated clay (FSC) under complex stress path, a series of directional shear tests were conducted using dynamic hollow cylinder testing apparatus of frozen soils (FHCA-300). Impacts of major principal stress direction and coefficient of intermediate principal stress on the stress-strain property of FSC were investigated through the directional shear tests. The results indicate that the stress-strain curves of FSC all perform as strain hardening under directional shearing, and the torsional shear component dominates the generalized shear stress-strain curves. Under different major principal stress directions, stress-strain curves of FSC have different levels correspondingly. When the coefficient of intermediate principal stress is 0.5 or 1, the level of generalized shear stress-strain curves will decrease with increase of the direction angle of major principal stress. The coefficient of intermediate principal stress has slight influence on the stress-strain property of torsional shear component, but has great influence on axial component and generalized stress-strain property.

Abstract:To fully study the strength characteristics of frozen clay under complex stress paths such as the variation of principal stress axis direction, a series of different principle stress direction shear experiments were carried out using the frozen soil hollow cylinder apparatus at a temperature of -10 ℃ to investigate the influence of the major principal stress orientation angle a (defined in the vertical plane), the intermediate principal stress ratio b and the mean principal stress p on the strength characteristics of frozen clay. Analyzing the generalized shear stress-generalized shear strain curves, the results showed that the strength of frozen clay was great influenced by the changes in a angle and p-value, and it was not affected by the changes in b-value. The failure strain was affected by the changes in these three parameters. The styles of stress-strain curves were all elastic-plastic strain harden curves and the range of elastic strain of the curves was about 0.5%, which was not affected by different stress paths. The strength model of frozen clay under different principle stress direction shear experiments was built through analyzing the relationship between stress and strain. Moreover, the relationship about generalized shear modulus E_Jt and strain was obtained, and the influence of initial shear modulus E_Jt0 on E_Jt-strain curves was also discussed. The threshold value of E_Jt0 was found and was about 6×10⁵ kPa for frozen clay. The changes in a angle, b-value and p-value had great influence on the strength characteristics of frozen clay.

Abstract:To study the marble particles' breakage process, morphology after breakage and force-displacement curve, the ball-surface and ball-ball particle contact experiments were carried out by employing Rock Rheological Testing System with customized spherical hinge bearings and a displacement measuring system, through which the mechanical properties and microscopic mechanism of marble particles' contact breakage are analyzed. The numerical simulation was performed to study the breakage process by considering the strength reduction parameter, and the result was compared with that of laboratory test, in which the experience on parameter calibration for contact simulation was introduced. This study shows that the local breakage is occurred firstly in the contact area, and then the Elastic Core is formed under normal contact force. The existing of the Elastic Core changes the path of force transfer and results in overall breakage of the particle after crack coalescence. The introduction of strength reduction parameter contributes to the simulation on the morphology after breakage. The result of numerical simulation forms a good supplement to the laboratory test, which further clarifies the microscopic mechanism of the contact breaking process of marble particles.

Abstract:To comprehensively analyze the creep, relaxation, long-term strength of serrate structure surface, the creep and stress relaxation tests of dentate discontinuity poured by cement mortar were carried out using biaxial creep machine under step load. Firstly, the similarities and differences between creep and relaxation were analyzed, and the differences of shear stress-displacement curves in creep process and relaxation process were compared. Secondly, a new stress relaxation model was presented based on the creep rate equation and the relations between creep and relaxation. Finally, the long term strength was determined separately by creep test and relaxation test, and contrastive analyses were made. The results show that the creep curve has similar shape with stress relaxation curve, but the trend of the creep curve is opposite to that of the stress relaxation curve. The creep deformation and stress relaxation amount increase with the increase of slope angles. The shear stress-displacement curve during creep test process and relaxation test process reveal the stress-strain path of creep differently from relaxation, which indicates the energy change in creep test different from relaxation test, so it cannot be simply considered to be equivalent between creep and relaxation due to the irreversibility of work. Though the stress relaxation model can fits the experimental data better, the differences among the orders of magnitude of the the parameter in creep equation and relaxation equation are 1 series. Based on the same mechanism, the long term strength of creep test is similar to that of relaxation test, in which the difference rate is about 9%. The long term strength is very close to yield strength in the shear stress-displacement curve of creep test and relaxation test.

Abstract:To study the application of airbags as a temporary plugging device in the tunnel engineering, the force analysis model was established to obtain the change law of the inner pressure and shape of the airbag as the external pressure increases. Two kinds of failure modes and three control conditions that need to be met during normal operation were obtained, in particular the unique control condition that the external pressure cannot be greater than the internal pressure. Since the matching degree between the airbag diameter and the tunnel directly affect the sealing effect, it is important to determine the allowable error range of the airbag diameter in the engineering design. Then the model tests were carried with three airbags with different matching degree. The deformation, internal and control conditions of the failure limit state were obtained. The results show that the airbag with the smallest deviation has the best sealability and the deformation and failure modes of the airbag are in good agreement with the theoretical formula. The airbag with a larger diameter has wrinkles, but the blocking effect and failure mode are similar to those with a moderate diameter. The smaller diameter of the airbag, due to a part of the internal pressure to offset the tension, has smaller maximum static friction resistance and it tends to slide under the external pressure. The allowable error of the airbag diameter is proposed, providing the basis for airbag manufacturing process.

Abstract:The reinforced concrete (RC) components strengthened with carbon fiber-reinforced polymer (CFRP) without fire protection measures are difficult to meet the standard requirements of fire resistance rating due to the flammability of CFRP. To study the fire performance of CFRP-strengthened RC beams based on the previous studies, nine RC beams with the same geometry and steel reinforcement were prepared with different strengthening methods and fire insulation schemes and tested under the ISO 834 standard fire. The test variables included various anchorage systems for externally bonded (EB) CFRP sheets (no anchorage, mechanical anchorage and U-wrap CFRP sheets), different fire insulation materials (intumescent fire-retardant coatings, cement-based fire protection mortar and cement mortar) and different thicknesses of fire insulation layers for different zones along the span direction. The temperature distributions and the deflection responses of these specimens under fire exposure were recorded and compared. It has demonstrated under this test condition that: U-wrap CFRP sheets used as the anchorage system are more efficient in limiting the deflection responses compared to the mechanical anchorage system; the combined use of the intumescent fire-retardant coatings and the cement mortar is practicable to protect the specimen from fire damage; the fire insulation provided by the 20 mm cement mortar and 2 mm intumescent fire-retardant coatings is better than that of 20 mm thick fire protection mortar.

Abstract:To evaluate the axial compression mechanical properties of brick walls strengthened with concrete splint, the brick walls were put on pressure by screw tension to simulate the brick wall under the vertical load and axial compression deformation after the reinforcement in the actual situation. The axial compression experiments of six walls reinforced by sandwich wall were carried out, in which the aspect ratios were set to 0.8, and 1.1 with the axial load ratios of 0.15, 0.25 and 0.35, respectively. The results show that the axial compressive deformation of the reinforced brick walls is uniform and the concrete wall on both sides of the reinforced walls is crushed before the brick wall under the additional axial pressure, which indicates that the bearing capacity of the reinforced walls is obviously improved by the concrete wall. Based on experimental results the strength utilization coefficient of the concrete and brick walls was introduced, and calculation formula of the brick wall reinforced by concrete splint was set up for limit bearing capacity calculation under the axial compression.

Abstract:Based on the bond stress-slip constitutive model between the reinforcement and concrete, a MATLAB program was coded to calculate the force of the headed bars, which was used to obtain the regulation of distribution between bond and headed bars of the high strength hot-roll reinforcement force, and it was validated by the pull-out tests of 120 reinforced concrete specimens. According to the simulation results, the combined effects of the relative concrete cover (the ratio of concrete cover c to bar diameter d) and an index f_y/f_t indicating the ratio of reinforcement yield strength to concrete tensile strength were investigated quantitatively. The results indicate that l_as/d (the ratio of the stable development length to bar diameter) increases linearly with f_y/f_t increase, but gradually decreases with the increasing c/d. The formula of l_as/d for f_y/f_t and c/d was established, and the potential influence factors of the bond stress f_b were evaluated, including reinforcement yield strength, concrete tensile strength, the relative concrete cover and the embedment length l_at. The results indicate that c/d is the only factor to constrain the parameter f_b/f_y to be varied with the index l_at/l_as. A reliable calculation formula of the f_b/f_y for c/d and l_at/l_as was proposed.

Abstract:Prestressed steel reinforced high-strength concrete (PSRHC) beams possess high load-carrying capacity and small section dimension, which is applicable to long-span and heavy-load buildings. To investigate the various design parameters' effects on the ductility of PSRHC beam members, the static behavior of PSRHC beam was simulated with numerical method and multi-parameter analysis was carried out. Based on the section fiber model, an analysis method, which could consider the confined effect of hoops, was firstly established to simulate the static behavior of PSRHC beams. Result shows that the analysis result has a good agreement with the test load-deflection curves. Then, the effect of parameters, including concrete class, amount of tension and compression rebar and prestress tendons, thickness of steel flange and web, and diameter and space of hoops, on the ductility of PSRHC beams was investigated. The results imply that: raising the concrete class, increasing the amount of compression rebar and hoops can improve the ductility of PSRHC beam members; increasing the amount of tension rebar, prestress tendons and thickness of steel web would decrease the ductility; and the effect of flange thickness is not obvious. When the hoop-space increases from 50 mm to 200 mm, the ductility coefficient decreases about 20.6%, and the diameter of hoop improves from 6mm to 10mm, the coefficient increases various from 18% to 34%. Finally, according to the simulation results, a regression formula, containing two parameters of hoops-volumetric ratio and complex reinforcement index, was proposed to evaluate the ductility of PSRHC members, and 3.1 was selected as demarcation value in this formula.

Abstract:To establish deformation limits of reinforced concrete(RC) beams, study on the method for classification of RC beams, definition of performance states and determining the deformation limit of specific performance state was conducted. As for the classification of RC beams, parameters affecting the failure modes of RC beams were investigated using collected test data for 103 RC beams tested under low frequency cyclic loading. A method was proposed to classify the failure modes into flexure-controlled and shear-controlled based on shear span ratio and moment shear ratio of beams. As for the performance states of RC beams and their deformation limits, the performance states of RC beams were divided into seven levels with reference to the current Chinese codes for seismic design, and the method for determining the deformation limits of these levels was put forward, which is based on three key performance points (point of yielding, point of losing 20% load capacity, point of losing bearing capacity) of the force-drift ratio backbone curves. With the test data of 103 RC beams, regression analysis of deformation limits was performed on multiple sets of parameters, key parameters and formula of deformation limits of the three key performance points were found for the flexure-controlled and shear-controlled RC beams. Deformation limits of flexure-controlled and shear-controlled RC beams were then put forward. To further verify the proposed deformation limits, quasi-static test of 9 RC beams was conducted, test deformation limits of three key performance points were obtained and compared to the proposed performance limits. The results show that the accuracy, discreteness and failure probability of the proposed RC beam deformation limits are all within reasonable range.

Abstract:To design free-form structures with reasonable mechanical behaviors and rich geometrical shapes, the principles of traditional form-finding methods by physical experiments were referred, and a numerical form-finding method for free-form structures was proposed based on the combination of the Dynamic Relaxation method and the Local Linearization method. As the zero bending moment type free-form structure has the same form with the flexible membrane structure which has the same loading distributions and boundary conditions, the form-finding of free-form shell structures can be realized by membrane structures. In the proposed method, equilibrium forms under different driving forces, such as the gravity, pneumatic pressure, pretension force, were generated by Dynamic Relaxation method, and the form-control problem aiming to meet the requirements of architectural design was explored by adjusting the initial parameters of the model using the Local Linearization method. The poposed form-finding method was applied to the inverse-hanging type shells, the pneumatic type shells and the tension type shells separately. For the inverse-hanging type shells, a model made by Isler was simulated, and the results were compared with the data by 3D scanning to verify the accuracy of the proposed method. For the pneumatic type shells, the multi-region controlling strategy was used to realize the form-finding of complicated shapes. For the tension type shells, the behaviors of a shell genertated by the form-finding method were analized to illustrate the zero bending moment feature. It can be concluded that the proposed method is more effective and applicable, which is helpful to realize the harmonious design of architecture and structure.

Abstract:To optimize the mechanical performance of steel plate shear wall (SPSW), a novel buckling restrained steel plate shear wall (CN-SPSW) was proposed. In the CN-SPSW, prestressted cable nets were placed on the either side of infill panels to restraint the early buckling, and the out-of-plane deformation would be restricted by the panel's pre-tension. A non-linear finite element model was established via ABAQUS software package to study the hysteretic behavior of CN-SPSWs. The results show that the cable net is a kind of flexible buckling-restrained member, and it can reduce the out-of-plane deformation of infill panels significantly. Compared with the steel plane shear wall, peak bearing capacity and energy dissipation capacity of CN-SPSW are increased by 18% and 47% respectively with a width-to-thickness ratio of 1 000. Parameter analyses suggest that prestressted cable nets should be applied to SPSW whose width-to-thickness ratio is more than 600.

Abstract:To predict the bending strength of 6082-T6 aluminum alloy flexural members, experimental studies of 24 tensile coupon tests and 19 three-point bending tests of box-section were performed. Finite element models using ABAQUS were developed and verified against the test results of 19 beams, and then used to perform parametric studies, in which a total of 468 numerical results were generated. The experimental and numerical results were used to evaluate the bending resistance provisions of the current American, European and Chinese Specifications. The impact of plate-assembly effect was not considered in these three specifications, which made the calculating process lightly complicated and the results relatively conservative. Based on direct strength method, the calculation method of bending strength considering the material nonlinear characteristics and initial geometric imperfection was proposed for 6082-T6 aluminum alloy bending members with box-section. Compared with the results of experimental data and three design specifications, it shows that the proposed calculation method is more accurate and convenient in predicting the bearing capacity of 6082-T6 aluminum alloy three-point bending beams of box-section.