Abstract:To promote the application of steel-concrete composite columns in mega column structures of super high-rise buildings, the key seismic technology and application of steel reinforced concrete (SRC) and concrete filled steel tube (CFT) columns are reviewed on the basis of a brief introduction of the mega frame structure with steel-concrete composite mega columns. Several technical issues on the steel-concrete composite mega columns that need to be further investigated are proposed. Research shows that the mega frame structure is an effective anti-seismic system, with perfect mechanical property. The finished and ongoing super high-rise buildings mostly utilize the mega frame structure with steel-concrete composite mega columns in China. Related studies mostly focuse on elastic-plastic analysis and shaking table test. The complex cross-sectional steel-concrete composite mega columns have good seismic performance after reasonable design. The related mechanical behavior theoretical calculation method with universality and the reasonable structural constructions are the key technical issues that urgently need to be further studied.

Abstract:Large amounts of existing masonry structures in urban construction intensive areas of China are faced with severe demands for demolition and reconstruction. Traditional demolition methods such as manual demolition, semi-manual demolition, and semi-mechanical demolition have problems of low demolition efficiency, high noise, heavy dust, and difficult recycling of demolition materials. Typical modern technologies (e.g., blasting demolition) are very dangerous and can easily produce huge noise and dust pollution to the surrounding environment. Demolition materials produced solely by traditional and modern demolition technologies are usually directly buried and difficult to be recycled. Therefore, green demolition methods and technologies of masonry structures should be developed to achieve low noise, low dust, and high recycling rate of demolition waste. In this study, five types of demolition techniques domestic and abroad were compared and analyzed, including manual demolition, crushing hammer, crushing ball, hydraulic scissors, and blasting method. The working principles, technical advantages, and application range of the techniques were summarized. The idea and method of dismantling masonry structure of wall cutting, lifting, transportation, and reassembling were proposed, which could provide support for demolishing and reusing masonry structures with high value.

Abstract:To study the effects of different site ground motions on curved bridges, a scale model of a curved bridge with the scale ratio of 1∶10 was designed by taking a curved bridge with 5% longitudinal slopes as the research object. Ground motions in different site conditions were selected for shaking table test. The results show that the influence of site conditions on the response of the curved bridge was significant. The structural response increased gradually with the site classification changing from I to IV. Compared to unidirectional input, the structural response under bidirectional input was obviously large. The structural response of the main girder was affected the directions of the excitation. When the bridge was excited by the ground motion in the longitudinal direction, the main girder moved horizontally androtated along the fixed pier simultaneously. When the bridge was excited by the ground motion in the transverse direction, the movement of main girder was mainly translational. The structural response of the curved bridge was related to the bridge arrangement and the direction of the principal seismic. When the curved bridge was parallel to the direction of the principal seismic, the tangential displacement response was remarkable. The radial displacement was more significant when it was perpendicular to the direction of the principal seismic. The smaller the angle between the displacement direction of the pier and the direction of the ground motion excitation was, the greater the displacement response of the pier became. The higher the pier height was, the more obvious the magnification of the displacement of the pier was, and the more sensitive the tangential displacement of the fixed pier was to the seismic response. When the curved bridge was parallel to the direction of the principal seismic in unidirectional input, the bearing of the low pier was easy to fall off. When bidirectional input and the curved bridge were perpendicular to the direction of the principal seismic, the high pier was easy to fall off. Therefore, much attention should be paid to the seismic design and analysis of curved bridges.

Abstract:In order to investigate the dynamic performance of a light steel frame structure with micro-crystalline foam plates, a shaking table test of a two-story single-span light steel frame with micro-crystalline foam plates was carried out. Three seismic waves, EL-Centro, Taft, and Zhangjiakou artificial wave, were selected in the test. The intensity of seismic ground motion range from 8 to 9 degrees. The structure vibration performance was analyzed through analyzing the structural natural period, stiffness, floor acceleration, and floor displacement. Suggestions for further engineering application of the structure were given. The experimental results show that under the action of seismic intensity of 9 degree, the internal light steel frame and wallboard skeletons were almost undamaged, except for the partial peeling-off of the wallboard skin and the out-of-plane torsion of some wallboards. The connection mode of the micro-crystalline foam plate and the frame could produce relative dislocation, which could reduce the inter-story displacement of the structure to a certain extent. The X-direction horizontal stiffness of the structure had a large degrade. However, there is no danger of collapse under the action of rare earthquake with seismic intensity of 9 degree, which can meet the seismic resistant requirements for large earthquakes. Flexible materials are needed to add to the reserved joints between adjacent walls to improve the impact and extrusion phenomenon between adjacent walls.

Abstract:To investigate the seismic performance of double-skin concrete-filled steel tubular (CFST) columns, a quasi-static test was conducted for 6 specimens with 3 section forms and 2 shear span ratios, and the same vertical load was applied to each specimen. The steel components of the specimens were set as circular steel tube, double-skin steel tube, and double-skin steel tube with cavity welded steel plate. Failure mode, hysteresis characteristics, bearing capacity, stiffness degradation, ductility, and energy consumption of the specimens were analyzed. Test results indicate that except for the single-cavity CFST column with shear span ratio of 2.2, the hysteretic curves of the other specimens are plump and the seismic performance is stable. The hysteretic curves of the specimens with the same drift ratio can be plumper by increasing the section steel ratio or the shear span ratio. Setting the inner steel tube and the cavity welded steel plate can improve the bearing capacity, and it can greatly enhance the ductility of the specimens with smaller shear span ratio. The initial stiffness can be significantly improved by reducing the shear span ratio, but the stiffness degradation rate is faster, and the cumulative damage effect is more significant. When the construction is set, the cumulative energy dissipation of the specimens with small shear span ratio is higher when the ultimate drift ratio is reached. Compared with the experimental results, the calculation results of the practical bearing capacity of the CFST column adopted in this study are conservative.

Abstract:In order to study the seismic performance of assembled lightweight steel frame with deformation controllable connection of geopolymer concrete wall, one assembled lightweight steel frame and three assembled lightweight steel frame specimens of different types of connection with geopolymer concrete wall were constructed and tested under cyclic loading. The main purpose of this study is to analyze the effect of the connection type on the load bearing capacity, ductility, energy dissipation ability, damage characteristics, and damage evolution law of the structure and to verify the reliability of the deformation controllable connection among the assembled components. Test and analysis results show that the connections among the components of the lightweight steel frame were reliable, and the assembled lightweight steel frame with deformation controllable connection geopolymer concrete wall exhibited good seismic performance. Geopolymer concrete wall had similar damage evolution law with common concrete walls. The relative displacement due to the deformation controllable connection between the wall and frame improved the ductility and deformability significantly, and prevented geopolymer concerte wall from cracking under frequent or moderate earthquakes. Assembled lightweight frame with deformation control connection geopolymer concrete wall have multiple seismic resistant measures, which can meet the seismic resistant requirements in earthquake-prone area.

Abstract:Located in the east of China, Tancheng-Lujiang fault zone is a region with frequent seismic events. Earthquakes above 4.0 occur multiple times there, most of which concentrate in its middle and northern segments. Yi-Shu fault zone is located in the middle of Tancheng-Lujiang fault zone, where earthquakes above 6.0 have occurred. To study the influence of sites on the ground motion of the Yi-Shu fault zone and explore groud motion estimating method for regions lack of seismic data, the ground motion wave form of Yi-Shu fault zone is analyzed by Fourier spectrum, and the high frequency reduction effect of sites in Shandong on Yi-Shu fault zone ground motion is studied. The high frequency reduction parameter Kappa is obtained, whose relationship with the site average shear wave velocity V_S30 is subsequently discussed. Kappa’s influence on seismic parameters such as PGA and response spectrum S_a is also investigated. Results show that as a parameter characterizing site conditions, Kappa exhibits regional differences, which decrease with the increase of corresponding V_S30. Under the same earthquake magnitude, Kappa only affects the numerical value of PGA and response spectrum, while their respective decay trends remained unaffected. The high frequency reduction parameter Kappa attains in this study can provide reference for research on the site effect in Shandong for earthquakes of Yi-Shu fault zone, as well as the simulation of the Yi-Shu fault zone ground motion and the analysis of its characteristics.

Abstract:To investigate the seismic energy response of a high-rise building considering the effect of soil-structure interaction (SSI) under seismic excitation, two shaking table test models, a fix-based (FB) model and a SSI model, were designed for simulating the high-rise building with frame-core tube structure based on the Buckingham π theorem and the principle of equivalent bending stiffness and strength. The original test data preprocessing method, energy equation of multi-degree-of-freedom system, and calculation method of the parameter matrix of the test model structure were explored in this study. Soil Effects on the dynamic characteristics and energy response of the superstructure of the two models were analyzed by comparing the kinetic energy, elastic strain energy, damping and hysteretic energy dissipation of soil under simulated seismic ground motions with different intensities. The results show that the energy response of the superstructure of the SSI test model was smaller than that of the FB model. The ratio of the soil damping of energy dissipation decreased with the increase of the seismic intensity. The soil could change the dynamic characteristics and energy response of the superstructure, but not the distribution trend of the energy response along the superstructure.

Abstract:To investigate the effect of the twisted wind flow on the wind effects of megatall buildings, a modified passive simulation technology, i.e., a combination of a self-developed vane system and the traditional passive simulation devices, is developed to simulate the twisted wind flow with a length scale of 1∶1 000. The mean wind speed and wind direction profiles determine by the field measurement, and the turbulence intensity profiles stipulated in the Chinese Load Code are determined to be the target wind characteristics for the thousand-meter high twisted wind flow. Then the effects of different devices on the twisted wind flow characteristics are analyzed in detail. Results show that the mean wind speed profile for the simulated twisted wind flow followed the power law with an exponent of 0.09, and the mean wind direction profile agrees well with the Ekman spiral with a maximum error of 1.5°. The simulated turbulence intensity profile fluctuate within those of the exposure categories C and D in Chinese Load Code, indicating the reasonability of the results. A good consistent wind property is obtained in an area of 2.5×1.5 m² around the center of the turntable with a range of -0.5[WT5,6”] — 2 m in the streamwise direction and -0.75[WT5,6”] — 0.75 m in the span wise direction. Thus, the simulated twisted wind flow can provide a solid basis for the further study of the characteristics of wind loads and wind-induced responses for thousand-meter high mega tall buildings, as well as systematic evaluation of the effects of twisted wind flow.

Abstract:To investigate the effects of depth-to-width ratio on the aerodynamic admittance of wind loads on rectangular high-rise buildings, wind tunnel pressure tests for high-rise buildings with depth-to-width ratios of 0.11[WT5,6”BZ〗 — 9 were conducted. Patterns of the aerodynamic admittances for fluctuating wind pressures on each wall and base drag were investigated under the orthogonal wind direction, which were then compared with quasi-steady assumption based Vickerys model and Solaris model. Closed-form expression for the aerodynamic admittance for base drag of buildings with different depth-to-width ratios was obtained through fitting analysis. Results show that when the depth-to-width ratio is lower than 0.5, the aerodynamic admittances for base drag and fluctuating pressures on the windward wall are close to Vickerys model.But as the ratio increases, the decay rate of the aerodynamic admittance becomes lower, and Vickerys model and Solaris model are significantly lower than the measured values.On the leeward and side walls, due to the effects of body-generated turbulence such as flow separation, reattachment, and vortex shedding, peaks with different sizes appear at high frequencies of the aerodynamic admittances for fluctuating pressures, where the varying pattern and magnitudes of Vickerys model no longer match. The fitted formula in power function form that obtained in this paper can well predict the aerodynamic admittance for base drag of rectangular buildings with different depth-to-width ratios.

Abstract:To improve fire resistance and thermal insulation performance of composite wall, composite wall of cold-formed steel and tailing microcrystalline foam glass slab (CFS-TS composite wall) was proposed, which was composed of cold-formed steel and tailing microcrystalline foam glass slab (TMFGS). CFS-TS composite wall can fill fly ash blocks between cold-formed steel keels to improve its thermal insulation and mechanical performance. To study the compression performance of CFS-TS composite wall, compressive tests of 4 composite walls were carried out to investigate the influences of the thickness of cold-formed steel, the strength of TMFGS, and the addition of fly ash block on the failure characteristics, bearing capacity, and deformation capacity of specimens. Finite element numerical simulation was conducted to clarify the influence of different parameters on the bearing capacity and failure mode of the composite walls. Simulation results had good agreement with the experimental results. The research shows that CFS-TS composite wall was under axial compression at the early stage of loading and under eccentric compression at the later stage of loading. When the specimen reached the ultimate load, buckling failure occured in the cold-formed steel. The thickness of the cold-formed steel has a great influence on the bearing capacity of the specimen. Increasing the thickness of the cold-formed steel can improve the stability of the specimen. Increasing the strength of the TMFGS can slow down the damage and improve the bearing capacity of the composite wall. When specimen was added with fly ash block, cold-formed steel, TMFGS, and fly ash block had good working performance with each other, and the compressive performance of the specimen was significantly improved.The section form of filling fly ash block is suggested to be used in the engineering application of CFS-TS composite wall.

Abstract:To investigate the influence of reinforcement cages and circular steel tube on special-shaped multi-cell concrete-filled steel tube (SMCFST) under reciprocating axial load, three large-size specimens were designed based on Z15 tower. The failure model, load-deformation curves, skeleton curves, bearing capacity, deformation capacity, stiffness degeneration, cumulative energy dissipation, and strain of the specimens were analyzed. Codes of different nations were utilized to calculate the bearing capacity of the specimens. The results shown that the reinforcement cages could enhance the initial stiffness and bearing capacity of the specimens. The circular steel tube could further improve the initial stiffness and bearing capacity, as well as significantly enhance the ductility, cumulative energy dissipation, and the behavior of the specimens at the later stage. Moreover, since the codes ignored the effect of horizontal diaphragms and the different buckling mechanisms between inner steel plate and outer steel plate, the calculation results were significantly lower than the experimental results. Therefore, it was necessary to further investigate the calculation method of the multi-cell concrete-filled steel tube. The circular steel tube was suggested to be used in buildings to improve the axial compression behavior of the special-shaped multi-cell concrete-filled steel tube.

Abstract:In order to overcome the shortcomings of precast composite beams, such as easy cracking in post-cast zone, poor ductility, and easy to damage, engineering cementitious composites (ECC) were used in the precast plate and post-cast area of composite beams. Bending tests were carried out on 11 beam specimens. The flexural properties and effects of the ECC plate thickness, connecting method of reinforcement, and reinforcement ratio on the flexural properties were investigated. Bearing capacity and displacement of its characteristic point were studied. The crack width was measured and the laws of crack development trend and damage evolution were analyzed. The results show that the load, displacement, and ductility of the precast beams with ECC plate and post-cast joints under cracking, yielding, and ultimate condition were higher than those of RC beams. The thicker the ECC plate was, the more significant the effect was. The reinforcement connection methods of steel sleeve and hoop-inserting could effectively transfer the reinforcement stress. The precast beam could effectively control the crack width in bending area, and the damage index was larger when it was damaged. However, it could still bear load when the damage was serious, which is suitable for the key joint of precast structure.

Abstract:The application of composite spiral stirrups confined reinforced concrete columns can improve the core concrete strength and realize high ductility, which can be utilized to design and construct important structures in seismic zones of high intensity. A total of 6 concrete columns confined by composite spiral stirrups were tested under eccentric loading with different stirrup spacing and axial force eccentricities, and the results were compared with other two conventional composite stirrups confined columns under the same condition. The relationships of axial force with lateral deformation, stirrup strain, and compressive strain at the edge of the compression zone were obtained. Failure modes of longitudinal reinforcement yield and concrete crushing of the columns occurred successively under different spacing and eccentricities. Test results indicate that when the spacing is smaller than 80 mm, the composite spiral stirrups confined columns exhibited higher bearing capacity than conventional columns, the strength of the confined concrete is increased, and the defined displacement ductility is improved. Furthermore, the dual-confinement to the concrete consisted of core confinement by spiral stirrups and surrounding confinement by rectangular stirrups had significant effects on failure modes. The failure of the specimen was mainly caused by crushing and spalling of the concrete after buckling of longitudinal reinforcement. It was observed in the tests that the rectangular stirrups continuously provided a superior confinement effect on concrete even after the peak load while the spiral stirrups lost its efficacy. Based on the failure mechanism and the contribution of two different transverse reinforcement, spiral stirrups and rectangular stirrups, a calculation formula for eccentric bearing capacity of composite spiral stirrups confined concrete columns was proposed.

Abstract:To study the fatigue failure model of steel round bars, the unstable propagation area, stable propagation area, and stable propagation length of fatigue crack were calculated based on the fracture criterion from an elliptical fracture model of steel and the true stress field at tip of fatigue crack in round bars. On the basis of the facts that fatigue crack propagation accelerated with the numbers of cyclic loading during fatigue tests, it was assumed that the stable propagation rate of fatigue crack and the numbers of cyclic loading of constructional steel round bars comply with a monotonically increasing power function. In other words, the stable propagation rate of fatigue crack and the numbers of cyclic loading of constructional steel round bars are monotonically increasing linear functions in double logarithmic coordinate system. A function expression between the stable propagation length of fatigue crack and the fatigue life of constructional steel round bars (i.e., the fatigue failure model of steel round bars) was derived by integrating the power function between the stable propagation rate of fatigue crack and the numbers of cyclic loading. The proposed fatigue failure model of steel round bars shows that the fatigue life is a complex function of nominal maximum stress, relative stress amplitude, and location and length of initial crack, which cannot be merely simplified as a function of stress amplitude. Fatigue tests under constant amplitude cyclic stress were carried out on Q345B steel round bars . The fatigue test results show that the fatigue life of Q345B steel round bars decreased with the increase of relative stress amplitude and nominal maximum stress. The fatigue model parameters were calibrated and the model accuracy was verified, according to fatigue test results of Q345B steel round bars .

Abstract:To explore the mechanical behavior of a new type of steel hanger joint of secondary beam to primary beam in timber structures, static vertical loading tests of eight specimens using the new hanger joint are carried out based on the ASTM test standards. The load-displacement curves of the joints between the secondary beams and primary beams, as well as two typical failure modes are obtained. By using ABAQUS, three-dimensional solid finite element model of the proposed joint is established. The accuracy of the finite element analysis is verified by comparing with the experimental results. Based on the parametric analysis of the hanger joints, the influence of the thickness and width of the hanger flanges on the shear capacity and stiffness of the joints is studied. Calibrated by the detailed stress analysis and the test results, a simplified mechanical model is proposed, and prediction formulae for the shear capacity and failure modes of the hanger joint are recommended, which are in good agreement with the experimental results.

Abstract:In order to solve the problems of low strength and brittle failure of fresh ice when used as building material, a kind of fiber-reinforced ice (FRI) material was prepared by using primary pulp fiber as reinforcing material. Firstly, the uniaxial compression tests were carried out for composite ice materials with different fiber contents (0%, 1%, 2%, 4%, 6%) at -15 ℃. To investigate the effects of temperature on the properties of the composite ice materials, tests were also carried out at -5 ℃ under the same conditions. The results show that the strength and ductility of the composite ice material were obviously better than fresh ice. Unlike the brittle failure of fresh ice, the failure of FRI was ductile failure, and the deformation ability was greatly enhanced compared with fresh ice. The strength, peak strain, and modulus of elasticity of the composite ice materials decreased with the increase of temperature, while the strength and peak strain of the composite ice materials increased with the increase of fiber content, and the elasticity modulus decreased. Based on the test results, the standard values of material strength were determined by the direct design method of probability reliability. The conclusions could provide reference for the application of composite ice materials in buildings.

Abstract:To study the influences of confinements and coarse aggregate types on compressive properties of ultra-high strength concrete (UHSC), UHSC specimens with different types of coarse aggregates (basalt, quartz, marble) and the same mix proportion as well as their matrix mortar specimens were investigated by conventional triaxial test under six confinements (0,5, 0,0, 0,0 MPa). Test results show that the coarse aggregate type had a significant impact on the peak stress and elastic modulus of UHSC. The deformations of UHSC specimens with coarse aggregates decreased significantly under the same axial stress compared with the matrix mortar specimens. The axial strain at the peak point of UHSC increased linearly with the confinement and the failure modes could be classified into three types under different confinements: splitting failure at 0 confinement, shear failure at 5-40 MPa confinements, and squeeze flow failure at 70 MPa confinement. The growth rate of the peak stress gradually slowed down with the increase of confinement. The strength growth rate of UHSC with coarse aggregate was higher than its matrix mortar specimen under low confinements, while their rates tended to be the same at 40-70 MPa confinements. Different aggregates had different resistance to crack propagation, and the proportion of cracks passing through marbles was much larger than quartzs. Comparison of the fitting results by using Mohr-Coulomb criterion and Ansari criterion shows that Ansari criterion was more accurate than Mohr-Coulomb criterion in reflecting the change trend of concrete strength with confinement.

Abstract:To theoretically analyze the mechanical behaviors of rheological rate effect, the rheological model of unsaturated soil should be formulated. First, the yield surfaces of unsaturated soil are divided into LC and SI yield surfaces. Second, based on the compression creep formula of the LC yield surface, the corresponding rate of viscoplastic volumetric strain is formulated by the equivalent-time method.Combined with Barcelona yield equation and the associated flow law, the three-dimensional rheological rate equation of the LC yield surface is obtained.Differences and similarities between the LC subsequent yield equation of Gennaro-Pereira are discussed. Then, based on the suction-induced compression creep formula of SI yield surface,the corresponding viscoplatic volumetric strain rate is formulated by the equivalent-time method. Finally, the equivalent-time three-dimensional elastic viscoplastic model of unsaturated soil is built combining the rheological rate equations of LC and SI yield surfaces with elastic equation.When the rheological rate effect is ignored, LC and SI rheological yield equations can be degenerated into the corresponding plastic yield equations of Barcelona model. One-dimensional rheological behaviors are theoretically analyzed,and the theoretical predicts and the soil test data are in relatively good agreement. The numerical analysis results of rheological behaviors under three-axial loading condition show that when the same dead loading is applied by several ways, along with the duration of dead loading, the rheological volumetric strains at different ways will tend to equalise value, but the rheological shear strains will have obviously different values.

Abstract:Prestressed concrete (PC) pipe pile has poor seismic performance compared with ordinary concrete piles. To improve the performance, a new type of mesh-constrained PC pipe pile is proposed. Through the quasi-static test of four PC pipe pile specimens, which are divided into two groups under different axial compression ratios, effects of reinforcement form and axial compression ratio on their seismic performance were investigated. One group had a new type of meshed constraint and the other had common spiral constraint. The axial compression ratios of each group were 0.3 and 0.5 respectively. The failure process was recorded in detail, and the hysteresis curve, skeleton curve, load-bearing capacity, deformation ability, stiffness degradation curve and energy consumption capacity of the test specimens were obtained. Results show that all test specimens were subjected to flexural failure, and the ductility factor was between 2.99 and 3.96. The meshed constrained test specimens had large energy consumption, and its hysteresis loop was fuller than the spiral constrained specimens. The load-bearing capacity, ductility and energy dissipation capacity of the specimens were greatly affected by the axial compression ratio. The larger the axial compression ratio, the greater the load-bearing capacity and the worse the ductility and energy dissipation capacity. A formula of flexural capacity of the PC pipe piles with meshed constrain stirrups is proposed and the formula of the PC pipe piles subjected to the high axial compressive ratio is modified.

Abstract:Assembled power eccentric foundation is a new type of foundation, which is designed and calculated according to existing standards, but the influence of horizontal force and soil on foundation design has not been discussed. To study the pull-out performance of this new assembled eccentric foundation, the ultimate pull-out capacity, the law of internal force transfer, and the stress of a single component of the foundation are analyzed under progressive loading of oblique loads by theoretical calculation and finite element simulation. To verify the correctness of the results, an indoor pull-up test of a scale model is designed. Based on the comparison of the results, it is found that the whole foundation do not undergo uplift failure. The downward transmitted force gradually become uniform with the increase of the depth of the foundation. The simplified calculation results of a single component are in good agreement with the experimental and the simulation results. The analysis of the internal force transfer law of foundation and the stress of individual member show that the overall uplift design method in the current code is still applicable to this new type of foundation. Horizontal force and soil have certain influence on the uplift of foundation, but the uplift resistance can be neglected. Thus, the simplified calculation method of single member is feasible.

Abstract:To solve the problems of steel tube column joints, such as insufficient anchorage strength and complex construction, steel tube column joints assembled by high strength steel core tube-bolt assemblies were proposed. The assemblies were composed of high strength steel core tubes embedded in steel tube columns and normal bolts. To study the static behavior of the new connections, six full scaled specimens of steel tubular column frame exterior joints were tested under monotonic loading. The research parameters included the types of the steel core tube, the thickness of the steel core tube plate, the bolt diameter, and the end-plate thickness. The stress distribution of the specimen key parts, the deformation capacity, the failure modes, the bolt tension stress, and the joint types were analyzed. Results show that the specimens were semi-rigid joints, and all joint failure modes belong to steel beam plastic hinge mechanisms. When the plate thickness of the enclosed type core tube was equal to the bolt diameter, the joint could satisfy the strength conditions of the rigid joint in the Chinese code. The deformation of the joint panel zone could be ignored, and the rotations of the core tubes were less than 10% of the total rotation. When the core tube plate thickness decreased, the width of the gap between the end-plate and the column would increase rapidly, and the bolt might be pulled out. The steel plate-bolt assembly tension force design value could be calculated as 70% of the tension bearing capacity of the threaded hole in high strength steel plates.

Abstract:Thin steel plate shear wall (SPSW) is a new type of lateral resistance structure suitable for high seismic intensity area, which relies on the tension field formed by the buckling of infilled thin steel plate to resist the horizontal load.It takes a long time to calculate and design SPSW using the detailed model.Thus, in order to improve the efficiency of the SPSW structure design,a simplified model of cross brace-strip model (CBSM)based on the strip model(SM)was proposed to simulate the lateral behavior of diagonally stiffened thin SPSW.The calculation formulas of initial stiffness and bearing capacity of the diagonally stiffened SPSW were derived. The detailed model and the CBSM were established by finite element software ABAQUS. The accuracy of the CBSM and the detailed model were verified by comparing the calculated results with the theoretical formula.The results showed that the detailed model, the simplified CBSM, and the theoretical formula had good consistency in predicting the bearing capacity of the diagonally stiffened thin SPSW with different spans, thicknesses, and stiffener stiffness.It was indicated that the simplified CBSM could accurately predict the bearing capacity of the diagonally stiffened thin SPSW and reflect the contribution of stiffeners to the lateral resistance of the SPSW structure.The theoretical formula of the initial stiffness agreed well with that of the detailed model, and the predicted stiffness of the CBSM was lower than that of the detailed model and therefore proved to be safe.

Abstract:To extract static data from building information models (BIM) for big data applications in building energy consumption monitoring, static data demands are analyzed firstly. On this basis, industry foundation classes(IFC) based static information models for building energy consumption monitoring are established. For the case where the IFC standard does not meet the static data requirements for building energy consumption monitoring, the IFC standard is extended. After the analysis and extension of the IFC standard, a method to extract the required static data from IFC files for big data applications in building energy consumption monitoring are proposed. Finally, based on the analysis of static data requirements for building energy consumption monitoring and the establishment of a static information model for building energy consumption monitoring based on IFC standard, a computer program is developed by C# language on Visual Studio 2017 to test and verify the proposed method. Results show that the proposed method is easier and more efficient than inputting data manually.

Abstract:To solve the problems of traditional snow depth measurement methods, such as large investment, time consuming, and low efficiency, a contactless method named Photogrammetry was proposed based on SfM (structure from motion). First, a series of experiments were conducted using the wind-snow combined experiment facility, and snow distribution photos were obtained by camera. Then, the three-dimensional coordinates of the snow surface were restored, and the spatial distribution data of the snow surface was extracted by MATLAB programming, which was compared with the snow depths that were measured by steel ruler to verify the accuracy of the method. The results showed that the accuracy was kept at ±2 mm and the relative error was within 1% when using photogrammetry for simple roofs. While when using photogrammetry for complex roofs, the accuracy was ±4 mm and the relative error was within 1%. It was proved that the accuracy of the photogrammetry method satisfied the measurement requirements of the tested model and the efficiency could be greatly improved when using photogrammetry for measuring snow depth distribution on complex test model roofs.