Abstract:In order to investigate the influence of different structural parameters on the seismic performance of low-rise lightweight steel buildings，the finite element model of lightweight steel building was established by ABAQUS based on the experimental results. It shows that the finite element analysis results，in terms of fundamental frequency，acceleration and displacement responses，agree well with the experimental results. Furthermore，a parametric study based on the verified model under 9-degree frequent occurring and maximum considered earthquakes was carried out. The results show that the increase of the sheathing number and adding diagonal bracing can improve the fundamental frequency，acceleration and displacement responses of buildings，but the change of the sheathing material has little effect on it; the wall opening ratio has obvious effect on the structural response of the building under earthquake. Thus，the wall opening ratio should not be greater than 29.09%; decreasing the aspect ratio and choosing regular plan layout of lightweight steel buildings result in the increase of the natural frequency and decrease of the acceleration response and displacement response.

Abstract:In order to study the collapse performance of beam-column structure with key-way joints and to study the effect of different post-cast concrete on its performance，static loading tests for two single-story two-span beam-column structures were performed. In the two specimens，ordinary C30 concrete and high ductility ECC concrete were poured at the key-way joints，respectively. The test dates of force displacement curve，failure mode and deformation performance were obtained. The research indicated that the beam-column structure with key-way joints developed beam mechanism，arch mechanism and catenary mechanism in turn during the deformation process under the requirements of the conventional seismic load. It was a good anti-collapse node form for the assembled structure. Relying on the superior material properties of ECC，such as high ductility and high ultimate compressive strain，beam-column structure with ECC key-way joints can exhibit greater load-carrying capacity and better ductility of joints. The local non-uniform relative slip between steel and concrete was conducive to the development of large deformation of the structure and improved the collapse resistance of the structure.

Abstract:In view of the time-dependent behavior of steel reinforced concrete (SRC) columns caused by creep and shrinkage under sustained loading，this paper provides an experimental study on the seismic behavior of SRC columns under low cyclic reversed loading，after they are subjected to axial sustained loading. Long-term axial deformations due to shrinkage and creep of the concrete were recorded，and the failure mode，deformation and strength of these columns in seismic test were analyzed. The test results indicate that the columns develope most of the creep deformation after 1 year of axial sustained loading. All columns fail in flexural-shear failure mode under the cyclic loading test. Whether or not the columns undergo sustained loading，the influence of steel reinforcement configuration and axial compression ratio on their seismic performance is similar to the conclusions drawn by previous studies. The deformation capacity and energy dissipation capacity of columns can be improved by adding steel tube in the columns. With the increase of axial compression ratio，the deformation capacity and energy dissipation capacity of columns decrease，but the shear capacity is improved. Sustained loading can lead to enlargement of yielding displacement，while it can decrease the initial stiffness and ductility coefficient in reinforced concrete columns. However，for the steel reinforced concrete columns，the influence of sustained loading on their seismic performance is restricted and weakened owing to the contribution of steel tube. Therefore，compared with the important design parameters such as steel reinforcement configuration and axial compression ratio，the influence of sustained loading on the seismic performance of SRC columns can be neglected in design.

Abstract:A new type of replaceable coupling beam（RCB） with O-shaped steel plate-viscoelastic combined damper at the mid span was proposed. The O-shaped steel plate damper, viscoelastic damper and combined damper were tested under low-cyclic loading. The test results show that the combined damper has strong energy-dissipation and deformation capacity. The design method for the structure installed with RCBs was proposed. The responses of a super-tall structure with RCBs under the wind and earthquakes were compared with those of the structure with traditional RC coupling beams. The results show that，under the wind and minor earthquake, viscoelastic dampers dissipate energy，while O-shaped steel plate dampers keep in elastic state. Under the rare earthquake，O-shaped steel plate dampers yield and dissipate energy together with viscoelastic damper. The combined dampers play the role of dissipating energy and reducing the response under the wind and the earthquake with different level of intensity. The structure with RCBs exhibits better wind resistance and earthquake resistance capacity than the traditional structures.

Abstract:To investigate the effects of basalt fiber-reinforced polymer (BFRP) layers and predamage levels on the axial compression behavior of BFRP-confined concrete，fourteen plain concrete cylinders were pre-loaded under axial compression loading. Three predamaged levels were considered. The predamaged cylinders were wrapped with three different BFRP layers and subjected to axial compression loading again. It is found that the ultimate strength and ultimate strain of the BFRP-confined predamaged concrete were 1.18~1.81 times and 5.94~10.55 times of those of the unconfined concrete，respectively. However，compared with the BFRP-confined undamaged concrete，the ultimate strength and initial elastic modulus of the BFRP-confined predamaged concrete were reduced by 7%~15% and 38%~55%，respectively，while the ultimate strain had little difference. The test results showed that the compression strength and deformation capacities of the damaged concrete exhibited good repair effect after BFRP confinement. However，the strength and initial elastic modulus of the BFRP-confined concrete tended to decrease with an increase of predamage level. Therefore，it will be unsafe to apply the existing mechanical model of FRP-confined undamaged concrete to the retrofit design of damaged structures. Based on the experimental results and collected literature data，a strength model，initial elastic modulus model and stress-strain relationship model of BFRP-confined concrete were proposed with considering the effect of predamage levels. The proposed models showed a good agreement with the experimental results.

Abstract:Based on the study of mechanical property test in normal weight concrete and lightweight concrete with different fiber volume fractions，the influence of steel fiber on the bond mechanism between deformed steel bar and reinforced concrete was discussed through the central pullout test program. It can be found that the ability to resist crack propagate of the concrete was increased because of the steel fiber added in the concrete. The bond behavior of the concrete was also increased. With the same fiber volume fractions in two concretes，normal weight concrete has a better performance to avoid the crack propagation than lightweight concrete. Therefore，the bond behavior of normal weight concrete is also better than that of lightweight concrete. The maximum increase of the reinforced concrete bond strength was 49.94% （normal weight concrete with 40 kg/m3 fiber volume fractions） and 51.94% （lightweight concrete with 60 kg/m3 fiber volume fractions），respectively. The research in this paper can provide theoretical reference for the follow-up research on the bonding performance and promote the application of lightweight aggregate steel fiber concrete in practical engineering.

Abstract:In order to investigate flexural behaviors of the bolted ball-cylinder（BBC） joint，based on 2 tests on joints under one-way bending moment，finite element （FE） model was developed in ABAQUS. Failure modes，bolt internal forces as well as the load-displacement curves of the joints were obtained. By comparison，it was found that the numerical results agreed well with the experimental results，verifying the reliability of the FE model. Subsequently，joint model under bending moment was simplified and the mechanical behaviors of joint under positive and negative moments were discussed. In the parametric study，46 FE models were established to investigate the effects of different parameters on flexural behaviors of the BBC joint. The results indicate that increasing the diameter and thickness of the hollow cylinder can improve the flexural behavior of the BBC joint significantly; while the bearing capacity and stiffness of the BBC joint increase with the increase of rectangular tube width，washer thickness，size and interval of the bolts，and the effects will be more obvious when positive moment is applied to the joint. Besides，the ribbed stiffness can improve flexural behavior of the BBC joint greatly.

Abstract:The existing connections for glulam/bamboo-concrete composite（BCC） beam，including notched connection and dowel connection，exhibit performance deficiencies. Therefore，a new kind of connection，named as reactive powder concrete（RPC）-steel composite connection，was presented for prefabricated BCC beams in this paper，in which steel screw with an axial hole was covered by a layer of RPC. Total 6 groups of specimens were performed by push-out tests. The major mechanical properties such as the load-slip curves，shear capacity and shear stiffness were measured and then evaluated. The results showed that the RPC coat significantly improved the shear stiffness of composite connection and increased the shear capacity in a certain degree，while the shear capacity was mainly decided by the diameter of steel screw. Compared with the notched connection and dowel connection，the proposed connection has higher carrying efficiency per unit area and higher shear stiffness，respectively. Therefore，the RPC-steel composite connection combines the merits of high shear stiffness and high ductility from two conventional connections，and it is fit to prefabricated construction. Based on the test results，the design size of the proposed connection was also provided.

Abstract:In order to understand the resistance of grid frame structure under horizontal loads，based on D-value method，assuming that axial force is linearly distributed on structural cross section and considering the influence of bending and shear deformation，this study deduced the equivalent lateral resisting stiffness formula under inverted triangular load，uniformly distributed load and vertex concentrated load. The results were compared with that of finite element method and experiment．The results show that lateral displacement of this structure is given priority to shear deformation，and with the increase of structure height，the influence of bending displacement becomes larger，so that the effect of bending displacement on the total lateral displacement should be considered. The influence of axial deformation of middle column on structural lateral resisting stiffness and displacement is smaller．Compared with the calculated lateral stiffness by finite element method or test results，the equivalent lateral stiffness formula in this paper has reliable calculation accuracy，and can be used to estimate the capability of resisting lateral deformation．

Abstract:Multiple square loops-string dome is a newly suspen-dome structure，and cable failure shows significant effect on multiple square loops-string dome structures. This paper used the Fuzhou Strait Olympic Center Gymnasium as the research background to study the effect of cable on the vertical stiffness of the roof，the internal forces of the roof and the ultimate bearing capacity，and safety capability evaluation of the cable failure roof was carried out. The analysis results show that the vertical deformation of the roof can be reduced after cable failure. Among them，the failure of the outer loop cable causes the maximum vertical deformation. However，various vertical deformation distributions subjected to different cable failure are generated. The failure of either the outer loop or string cable can increase the tension force of the adjacent cable significantly. The interaction between the outer loop cable and string cable is greater than the mutual influence between the other loop cables; Ultimate bearing capacity of the roof can be reduced when cable failure occurs，which reaches the minimum value when the outer loop cable fails. It should be noted that “Only one side string cable failure” causes more serious deflection and less ultimate bearing capacity when compared with“two side string cable failure”. In all，failure of the outer loop cable is the most serious case，which causes that vertical deflection increases by 134%，the cable tension force of adjacent cable increases by 11.7%，and the ultimate bearing capacity reduces by 35%. However，the residual roof structure is still in a safe state.

Abstract:Based on torsional motion-induced device with programmable vibration frequency and amplitude，the time history of wind pressure and displacement for each measurement point on the high-rise building model surface was measured by synchronous multi-pressure sensing system in wind tunnel test. The identification method of structure torsional aero-elastic effect was derived. The torsional aero-elastic effects of rectangular high-rise buildings with different wind speeds，amplitudes and stiffness eccentricities were evaluated. The test results show that the torsional aerodynamic stiffness is negligible，but the torsional aerodynamic damping should be taken into consideration. Especially，when the wind speed reaches the critical wind speed，aerodynamic damping decreases rapidly and comes into negative aerodynamic damping.

Abstract:In order to study the frequency domain characteristics of wind loads on high-rise buildings under downburst，using the impinging jet device to simulate thunderstorm downburst，pressure test was carried out on rectangular high-rise building models with different aspect ratios（D/B）. According to the test data，the power spectrum densities，correlation coefficients and coherence were analyzed in detail. The results show that the drag coefficient spectra are consistent with those of longitudinal wind spectrum of oncoming wind. With the increase of radial distance，the bandwidth of the drag coefficient spectrum becomes wider，and the main frequency and energy gradually decrease. The lift and torque coefficient spectra vary with the increase of the aspect ratio of the models，but the change is not obvious，which may be mainly affected by the special turbulent wind field of thunderstorm downburst. The radial distance and the aspect ratio have greater influence on the correlation of the drag coefficient，but less on the correlation of the lift and torque coefficients. The coherence of layer drag coefficient decreases linearly with the increase of frequency. The coherence of layer lift coefficient keeps stable in low frequency band，and it decreases exponentially with the increase of frequency. The layer torque coefficient is relatively small，and it decreases exponentially with the increase of frequency.

Abstract:In order to study the anti-reflective crack performance of stress-absorption interlayer (SAI)，the Overlay Test（OT） was used to determine the anti-reflective cracking performance of SBS，WTR and WTR/APAO modified asphalt SAI under standard conditions，after moisture damage and long-term aging. The research shows that the cycle number，reduction in load and total fracture energy can characterize the anti-reflective cracking performance of SAI. The maximum load in the first cycle and critical fracture energy are indicators for evaluating initial cracking. It is found that three stress-absorption interlayers have good anti-reflective cracking performance under standard conditions. However，the moisture damage has a great influence on the crack resistance of WTR/APAO. The anti-reflective cracking performances of WTR and WTR/APAO are greatly reduced after long-term aging. The OT maximum load-cycle number curve of three SAIs is in accordance with power function.

Abstract:A reliability calculation method is proposed to calculate the reliability of structure with complex implicit function like steel truss structures. It firstly adopts the neural network to approach the implicit function in service ability limit state and NGA (New Genetic Algorithm) is employed to obtain the optimal solution of reliability index of steel truss structures and its design point on the basis of the geometric implication of reliability index. Finally，JC method and Monte Carlo Critical Sampling Method are introduced，respectively，in two examples to verify the accuracy and validity of NGA. The results manifest that the relative error is only 0.23 percent when NGA and Monte Carlo Method are used，respectively，to calculate the reliability index of steel truss. In addition，the introduction of adaptive random variable can greatly improve the gene of initial population for small probability failure structures. All above prove that NGA is of significance in practical projects for calculating the reliability index of structure with complex implicit function due to its advantages of fast computation speed and high precision.

Abstract:In consideration of the weak rock conditions of rock-socketed piles and taking the dilatancy of the interface into account，the constant normal stiffness conditions (CNS) were applied to simulate the lateral constraints provided by weak rock，and laboratory model tests were conducted to inquire the mobilization of the side resistance. The asperity of the concrete-rock interface can be idealized as regular sawtooth asperities，and sandstone and concrete specimens were manufactured with different half-chord lengths，respectively. The relevant measurements were observed，such as shear load，shear displacement，normal load and normal displacement. In addition，the observations showed that the dilatancy angle of the interface gradually decreased with the development of shear displacement. The shear strength of interface is closely related with the normal constant stiffness and the half chord of the rough body as well as the shear displacement. Based on the consideration of elastic compression of the asperity，the empirical relationship for the shear strength of weak rock was fitted by power functions. On the other hand，the observations were compared with the predictions of an existing theoretical model，and it was shown that the theoretical model can overestimate the side resistance of the rock-socketed piles，due to the disregard of nonlinear variation of the dilatancy angle.

Abstract:Aiming at the insufficient research on the complex sliding-toppling failure of anti-dip rock slopes，the geological model of complex sliding-block-flexural toppling failure was constructed，firstly，which contains the sliding，block toppling and flexural toppling zones. Next，based on the failure mechanisms of these three zones，their mechanical models were established，respectively. Then，the stability analysis approach of the complex sliding-block-flexural toppling failure was proposed according to the limit equilibrium theory and the cantilever beam model. Finally，one case study was performed for practical verification on the proposed geomechanics models and analysis approach. The results show that the stability of the complex sliding-block-flexural toppling zones is controlled by the block-flexural toppling zones. Further，the block and flexural toppling zones are active and passive failure zones，respectively. Consequently，the block toppling zone plays a vital role in slope design treatment.

Abstract:Low frequency uniaxial cyclic loading and unloading experiments on red sandstone were carried out to study the fatigue deformation，damage characteristics and energy evolution of red sandstone by using RYL-600 microcomputer controlled shear rheometer. The experiment results are as follows. The threshold value of fatigue failure stress of the red sandstone is between 75% and 85% and the fatigue life decreases sharply with the increase of upper stress. Under the condition of low-frequency uniaxial cyclic loading and unloading，the axial deformation of red sandstone is divided into three stages. In the initial stage，strain is small but grows rapidly; in the stable stage，strain gradually increases slowly; in the near failure stage，strain and strain increment increases rapidly. In the three stages，the density of hysteresis loop presents the characteristics of sparsity - density - sparsity. The shape of a single hysteretic loop shows the development rule of "fat - thin - fat". The area of a single hysteretic loop increases with the increase of upper limit stress. The damage development process is divided into initial stage，steady expansion stage and accelerated damage stage. The higher the upper limit of stress is，the faster the damage develops. In the three stages，the accelerated failure stage，which occupies the smallest part of fatigue life，produces the majority of damage increment. The number of elastic energy cycles first increases and then remains stable. However，it decreases with the decrease of material elasticity in accelerated damage stage. The initial value of dissipated energy is large，and then it decreases with the increase of cycle number and then tends to be stable. When it is close to failure，it increases sharply by nearly 4 times，indicating that the rock failure must be accompanied by the sharply increase of dissipated energy. The internal stress adjustment of rock is reflected in the evolution of hysteretic loop. The larger the hysteretic loop area is，the larger the single plastic deformation is，the higher the damage degree is，and the more serious the energy dissipation is.

Abstract:To reveal the rock breaking characteristic of disc hob under true triaxial condition, the Drucker-Prager strength theory, CSM model and intermediate principle stress coefficient β were used to establish a theoretical calculation model and a simulation analysis model, which can be used to study the fracture characteristic of rock and the stress characteristic of hob under high ground stress. The results show that the extreme value of vertical force decreases remarkably after rock is damaged, while the range of rolling force and lateral force changes little. The lateral force is always smaller with constantly changing direction, leading to the vibration and uneven wear for cutters. With the increase of intermediate principal stress effect, the number of crushing elements decreases exponentially, and the maximum force in vertical, rolling, and lateral directions increases exponentially, in which the increase of the lateral force is the smallest. With the increase of penetration, the number of crushing units and the rock breaking force increases simultaneously, and the increase extent also becomes larger, in which the increase of the lateral force is the largest. The relative errors among actual values, theoretical calculation values and simulation results are very small, which can verify the reliability and accuracy of the theoretical model and simulation model.