Abstract:In terms of the prestressed spatial structure system consisted of prestressed and giant reticulated shell structure，the arrangement principle of cables and struts，force mechanism，configuration and topological relations for existing two types of cable-strut arrangements were summarized.Based on the above analysis，two improved kinds of cable-strut arrangement schemes were put forward.Through the comparison of the structures with the existing two types of cable-strut arrangements and the corresponding non-pretensioned truss arch in five aspects including maximum displacement，horizontal reaction force，peak value of member internal force，ultimate load and buckling mode，the static performance and stability of the truss arches，the responses of two improved cable-strut arrangement schemes were studied.The results indicate that the structural rigidity，static performance and stability of truss arches can be effectively improved for the introduction of improved cable-strut arrangement schemes.Additionally，the defects of the existing two types can be ameliorated，which demonstrates the reasonable arrangements of the cables and struts in the two improved schemes.Comparatively，the second improved scheme had optimized comprehensive performance，and it is more efficiency.

Abstract:In order to determine the optimal force system of a large-span spatial structure (LSSS)，based on the morphological knowledge and basic theory of ESO method，the three-dimensional solid model of an initial design domain was established by ANSYS software；and by taking the status of every unit as the design variables and the minimum volume as the objective function，the ESO method was then applied to the LSSS for structural force system optimization.To meet the architectural intent and the restrictions of special foundation conditions，the arch-bearing force system of steel structure was finally presented.Eventually，by comparing the static analysis results of the deformation and inner force for structural force systems determined by the ESO method and original inverse hanging method，the feasibility and availability of the ESO method was demonstrated.It is shown that the topology optimization methods are essential and necessary for optimizing structural force system of the LSSS.

Abstract:In order to improve the deformation capacity of the steel frame structure so as to enhance the seismic performance，in this paper，a concerted deformation mechanism between the steel beam and panel zone was built by increasing the shear deformation of the panel zone so that the rotation demand of the steel beam may be reduced.Nonlinear finite element (FE) models of the steel frame beam-column joints were also established by using MSC.Marc.The results from the FE models fit well with the test data.Based on the reasonability of the FE models，parametric analyses were carried out to explore the relationship between the shear deformation of the panel zone and the deformation of the beam end in the beam-column joints when the story drift ratio is 0.04.The key parameters that affect the deformation of the beam end and the panel zone were identified.A simplified design method of the concerted deformation between the steel beam and panel zone was proposed，which may provide references for seismic design of the steel frame beam-column joints under rare earthquakes.

Abstract:The stress concentration factors of concrete-filled tubular Y-joints subject to in-plane bending were studied，based on the engineering background of the first 750 kV concrete filled tubular substation in China.Experimental investigation was performed to investigate the hot spot stress distribution along the intersection between chord and brace.Three tubular Y-joint specimens with circular concrete-filled chords under different forms of reinforced components，including doubler-plate，sleeved and haunched reinforced joints，were tested.In addition，a unreinforced joint specimen was tested for comparison.The test results indicate that three different forms of reinforced components effectively reduce the peak stress concentration factors of Y-joints，compared with that of the unreinforced joint.The current research points out that the linear extrapolation method can be used for chords，whereas the quadratic extrapolation method can be used for braces.The stress concentration factor values are effectively reduced and more evenly distributed when the axial compression ratio in chord is increased.Furthermore，the stress concentration factors obtained from the test results were compared with the predictions from some well-established existing stress concentration factor equations.Generally，the prediction results are very consistent with the test results of the braces，but very conservative for concrete-filled chords.

Abstract:In order to investigate the vibration mitigation performance of the Tuned Liquid- Particle Damper (TL-PD) during earthquakes，a series of shaking table tests were conducted on a steel frame structure with different damping devices，including Tuned Liquid Damper (TLD)，Particle Damper (PD)，and TL-PD.During the testing，three ground motions were adopted as excitation inputs.Testing results show that the TL-PD has a good vibration suppression effect.The root-mean-square values of displacement and acceleration responses of the structure can be reduced by 63.2% and 50.5% at most，respectively.The TL-PD also shows a better robustness than that of the TLD，although the performance of the TL-PD is still influenced by the ground motion characteristics.Additionally，the TL-PD produced less noise than that of the PD in the tests.Based on empirical model，a mathematical model was developed to capture the behaviors of TL-PD in the preliminary design.

Abstract:In order to investigate the effects of MR dampers on vibration mitigation and dynamic reliability of structures，shaking table tests on the structures with and without MR dampers subjected to random earthquake ground motions were carried out.The reliability assessments of the controlled and uncontrolled structures were respectively performed using the extreme value distribution theory and the probability density evolution method.In the shaking table tests，representative time histories of ground accelerations were generated by employing a physical stochastic ground motion model.Experimental and analytical results reveal that the mean and standard deviation of inter-story drifts of the structure with MR dampers are significantly less than those in the uncontrolled cases，respectively，and the absolute accelerations of most floors are reduced to some extent；the variability in dynamic responses of the controlled and uncontrolled structures subjected to random earthquake ground motions is obvious，and the vibration control effect of MR dampers is significant when the structure is under various ground motions；the seismic reliability of each story as well as the whole structure is evidently enhanced after the installation of MR dampers.

Abstract:The structural behavior and load-carrying capacity of multi-planar column joints in a tubular tower were investigated under static loading in the test instrument of self-balancing frame with two full-scale test specimens.Based on this，the nonlinear finite element models were established.The analysis results were compared with the experimental results，which showed good agreement.The parametric analyses were also performed by reasonable and credible finite element models.The investigation indicates that the concave deformation occurs in their main pipes without the failure of branches and welds.All the measuring points of the joints are basically kept in linear elastic condition under design loads，showing that the design for the joint is very safe.Moreover，the ratio of chord radius to thickness has significant influence on the ultimate strength.The load-carrying capacity of the joint is improved with the growth of wall thickness when the diameter of chord is large.However，it increases slowly with the increase of wall thickness when the diameter is small.〖JP2〗The brace with small diameter and wall thickness is easily yielded and shows flexural buckling.

Abstract:Based on the time history of wind pressure collected from the wind tunnel tests on a high-rise building at Xiamen coast，four points with obvious non-Gaussian characteristics were found out by the calculation of fractal dimension，skewness and kurtosis.Considering the fractal characteristics of time history of fluctuating wind and the correlation distortion method，the non-Gaussian fluctuating wind pressure was simulated by adopting fractal Weierstrass-Mandelbrot function.Comparison of simulation results with experimental results in the aspects of probability distribution，power spectrum，fractal box dimension，skewness and kurtosis，showed better consistency.Therefore，it is feasible to simulate the fluctuating wind pressure with non-Gaussian characteristics by using fractal method.The method makes up for the shortcomings of traditional linear filter and superposition of harmonic，and provides a reference for the simulation of non-Gaussian fluctuating wind pressure.

Abstract:In order to analyze the influence of construction errors on the reliability of the Reinforced Concrete frame structure，based on the on-site measurement of one real RC frame engineering，the statistical distribution of the construction error，such as the beam column section size，the thickness of protection layer，stirrup spacing and concrete compressive strength et al.，was obtained.Based on the basic theory of structural reliability and the bearing capacity limit state equation，the reliability index of the typical frame beam and frame column in the real engineering was calculated by means of the checking point method.The influence of each construction error on the component reliability index and reliability grading of reinforced concrete frame structure was also analyzed，and the parameters sensitivity of the RC frame structure reliability was discovered.The construction errors have unnegligible influence on the reliability of RC frame members.The results are conductive to the control of critical parameters and its error in the design，construction and monitoring of real engineering.

Abstract:Construction monitoring is related to the safety of engineering structure.However，the research of construction monitoring is limited in building engineering involved with curved prestressed concrete box girder.Combined with engineering practice of a student activity center venue，the monitoring scheme was made and conducted to ensure the safety in erection process for the curved box girder subjected to large force at the same time，and to keep tracking the whole process of construction.Construction simulation for a butterfly-shaped roof structure of the venue was conducted based on Midas Gen finite element software.According to the actual construction process and the element birth and death technology，the stress and displacement changing tendency of the roof box girder were analyzed in detail.The results derived by the monitoring and simulation were compared.The results show that the simulation method was validated by the good agreement between the results obtained from monitoring and simulation.The stress and displacement of the box girder are in control，and the construction scheme can satisfy the need of construction.The research results provide important reference for the design and construction of the similar large profiled component in building engineering.

Abstract:This paper performed a measurement experiment of pedestrian incentive for a reinforced concrete frame teaching building.Two finite element models were established，where one considers the influence of infilled wall and other without considering that influence，while the effect of stairs is included.Two finite element models were fixed by comparing the calculated natural vibration period with the measured natural vibration period.Three working conditions，static load，no load and pedestrian incentive load，were considered by choosing different live load.An IDA calculation analysis was conducted in order to study the seismic dynamic response of the two models under three different working conditions as well as the influence of the infilled wall on finite element model for structure dynamic performance.The results show that the infilled wall should be considered in the IDA analysis for the reinforced concrete frame teaching building considering the influence of pedestrian incentive load，the structural performance is the best when no load is applied and the static load takes the second place，and the worst is for the structure under pedestrian incentive load condition.

Abstract:A new precast concrete beam-column joint connected by I-shaped section steel was presented.The precast concrete beam-column joint was tested under reversed cyclic loading.According to the characteristics of the I-shaped section steel connection，a simplified equivalent cross connection model was proposed to simulate the joint.Based on the experimental results of the joint and the stochastic point scattered in two-dimensional space，the equivalent elastic modulus of concrete and yield strength of steel bar were identified in the simplified cross connection model.Therefore，the hysteretic curve of the prefabricated concrete beam-column joint could be simulated easily by finite element analysis.A precast RC frame structure with six floors and three spans constructed by the precast concrete beam-column joint and a cast-in-situ RC frame structure with the same section and the same reinforcement ratio with the precast beam and column were analyzed by Pushover method.Meanwhile，according to the parameters identified from the experimental results，the nonlinear numerical simulation of the precast RC frame structure under seismic excitation was developed.The experimental results show the hysteric curve of the precast concrete beam-column joint was plump.The numerical simulation results present that the precast RC frame structure exhibits the satisfactory load-carrying and deformation capacity.Thus，the presented precast concrete beam-column joint can be used as a connected type for the fabricated concrete frame structure.

Abstract:The ice-shedding way of iced conductors affects the dynamic response of transmission line system.In this paper，a finite element model of 4 towers and 5 spans is established by numerical method，and the ice is simulated by additional ice element method.The dynamic responses of the structure are analyzed when two-layer ice at mid-span of the middle conductor peels off at the same time and at different time with different thicknesses.The results show that the maximum rebound height，unbalanced tension and wire tension induced by one time ice-shedding are 24%，17% and 14% lower than those by ice-shedding at different time，respectively.The maximum rebound height of the system occurs when the second layer ice peels off and the conductor moves to the lowest position at the same time.The structure exhibits the same stable vibration state regardless of the interval time of the two ice layers shedding.When the thickness of outermost layer accounts for 3/5，the effect of ice layers shedding is minimal.The conclusions obtained by ice layer shedding research show that the values of ice-shedding load based on the assumption of one time ice-shedding are conservative，and there is some space for optimization.

Abstract:The force mechanism was analyzed and the moment-rotation calculation formulas were deduced for the straight mortise-tenon joints.Good agreement between the predictions and test results was observed.Based on the moment-rotation calculation formulas,the factors affecting the rotational stiffness of the straight mortise-tenon joints were analyzed.The results show that:the rotational moment and initial rotational stiffness are increased significantly with the increase of the length of a tenon when the ratio of the length to the column diameter is less than 1;the rotational moment and initial rotational stiffness are also improved with the increase of the width of a tenon;the rotation moment of the joint is increased to a certain extent with the increase of the friction coefficients,but the initial rotational stiffness is affected little.The conclusins are helpful in the seismic performance assessment and reinforcement of the traditional wooden buildings.

Abstract:Combined with uniform design and response surface method and Nataf transformation,an alternative seismic fragility analysis method,which can take the uncertainties of ground motions and structures as well as the correlations of structural random variables into account,was proposed.This study took a continuous girder bridge as case-study.The bridge seismic fragility analysis was performed,considering the dependence and correlations of structural random variables.Meanwhile,the seismic fragility analysis and the accuracy of the response surface model affected by the correlations of structural random variables were analyzed.The analysis result indicates that the proposed method can effectively take the correlations of structural random variables into account.After considering the correlations of the structural random variables,the established response surface can better fit the surface limit state function of structure,the probability failure of bridge in each damage state has a certain degree of reduction,and neglecting the correlations of structural random variables may underestimate the seismic performance of the bridge.

Abstract:In order to study the degradation law of the mechanical properties of PBL (Perfobond Leiste) shears connectors in steel-concrete composite structure under fatigue load，nine push-out PBL connectors were designed and fabricated to perform the static and fatigue tests.Among them，three static tests focused on examining the failure mode，ultimate load-carrying capacity and load-slip curves.The remaining 6 specimens were prepared for the static failure tests after a certain number of fatigue loads.Taking the cyclic number and the fatigue load ratio as the variables，the variation of the mechanical properties of the PBL connector，such as ultimate load-carrying capacity，residual slip，and shear stiffness，were obtained.The results show that：(1) PBL connector exhibits good ductility，and failure mode of the static and fatigue test specimens is all that one side of perforated steel bar cut and the other side yielded.(2) Fatigue load ratio has a significant effect on the residual strength of PBL connector.After 300 million number of cyclic loading，the ultimate load-carrying capacity is not degraded when the load ratio is 0.5，whereas it is reduced to 76.1% of initial value when the load ratio is 0.7.In the case of the same load ratio of 0.6，the load-carrying capacity tends to be slow first and then fast with the increase of fatigue cyclic number.(3) Compared with the load ratio，the residual slip is more sensitive to the fatigue cyclic number.Meanwhile，the shear stiffness is constant in the whole loading process.

Abstract:Thermal sensors have been installed on a curved bridge of high-speed rail.By means of carrying out 2 years monitor of CRTS II ballastless track，the time-varing rules are revealed.Through daily temperature data calculated from the measured data by using difference method of time series，the time-varing curve of uniform temperature，which represents the trend of bulk temperature change laws，can be obtained.Then，the rules of track temperature variance with atmospheric temperature are effectively reflected.In order to examine the change law of uniform temperature，Fourier curve fitting and high-moment statistical model are utilized，and the overall curve representing the changing laws of track temperature are put forward.The results show that the track uniform temperature appeared trigonometric development with a tropical year (namely 365 days) as a cycle，and the regression parameters can represent its median，amplitude and phase-difference.The entire section of the track can be analyzed as a whole，because the fitting results among test points are close，which indicates that the changing laws of track uniform temperature can be expressed by its overall curve.By using high-moment statistical model to analyze the differences between overall curve and its fitting curve，the representative value of overall curve with probabilistic guarantee can be obtained.

Abstract:The mean stress correction model of random-amplitude fatigue stress spectrum and cumulative damage model for HRB500 reinforcing bar used in longitudinally connected ballastless track on bridge in service life under combined loads were studied to provide the support for the establishment of fatigue life prediction model for above mentioned HRB500 reinforcing bar.Through the constant-amplitude fatigue tests on standard specimens of HRB500 reinforcing bar，the influence law of mean stress on fatigue life of HRB500 reinforcing bar was studied，and the applicability of mean stress correction models of random-amplitude fatigue stress spectrum commonly used in practical engineering to HRB500 reinforcing bar was studied.Through the three-level variable-amplitude fatigue tests on standard specimens of HRB500 reinforcing bar，the applicability of Miner’s rule to the calculation of cumulative damage of the HRB500 reinforcing bar was analyzed.The research results show that the fatigue life of standard specimens of HRB500 reinforcing bar decreases with the increase of mean stress，Goodman model widely used in practical engineering is applicable to the mean stress correction of HRB500 reinforcing bar under random-amplitude loading，and Miner’s rule is suitable to calculate the cumulative damage of HRB500 reinforcing bar used in longitudinally connected ballastless track on bridge in service life under combined loads.

Abstract:The simulation of saturated and unsaturated seepage under rainfall conditions was carried out by self-programming system using the built-in FISH language based on the seepage module of finite difference software FLAC3D and the unsaturated seepage theory.The pore water pressure and degree of saturation of the widened embankment under rainfall conditions were analyzed.The effects of geogrid reinforcement and permeability coefficient on the stability of the widened embankment were also investigated.The results show that the soil matric suction decreases rapidly and the slope reaches to saturated state and forms the transient saturated zone firstly.The safety factor of the widened embankment decreases obviously,considering the effect of rainfall infiltration.The geogrid reinforcement reduces the effect of rainfall infiltration on the stability of the widened embankment.Meanwhile,the permeability coefficient of the newly constructed embankment has large effect on the stability of the widened embankment under rainfall conditions.In practical engineering,the degree of compaction of the embankment fill should be guaranteed and the measures of slope protection should be taken to reduce the effect of the rainfall infiltration.

Abstract:In order to investigate the performance of European rock asphalt modified asphalt mixture，modified asphalt binder containing up to 20% of European rock asphalt was prepared.Design of AC-20C modified asphalt mixture with different percentages of rock asphalt was conducted.Performance tests were carried out on the specimens with optimum asphalt contents of respective percentages of rock asphalt.Based on the test results，the properties such as dynamic stability，Marshall stability，flow value，Marshall quotient，retained Marshall stability，indirect tensile strength ratio，flexural tensile strain，compression moduli at 15 ℃ and 20 ℃，and indirect tensile strength at 15 ℃ were analyzed.The analyses indicate that with the increasing percentage of rock asphalt，the high temperature stability and the moisture susceptibility of the modified asphalt mixture wer improved，and the stiffness and strength of the modified asphalt mixture increased.With the increasing percentage of rock asphalt，the low-temperature cracking resistance of the modified asphalt mixture increased to the peak value，and then fell down slightly.Considering the overall performance，the recommended optimum use of European rock asphalt in the modified asphalt binder ranged from 10% to 20%.

Abstract:On the basis of the existing researches，Hill failure mechanism and its slip line solution for the ultimate bearing capacity of flat ground foundation and slope foundation were put forward without considering the foundation soil gravity.The failure mechanism of the strip footings near slope was a continuous variation mode.It should be between failure modes of the flat ground foundation and slope foundation.In the same boundary conditions，the bearing capacity of the slip line solution was a continuous function between the two critical foundation states，as the distance from the top of slope was variable.The bilateral asymmetric Hill failure mode of the strip footing near slope was thus put forward.Then，on the basis of the study，the basal pressure zone was divided into two uniform compressive areas by introducing the width ratio.The stress influence on the slope slider was simplified by using the equivalent free surface.The limit pressure on the slope slide can be then calculated by slip line solution for the slope foundation.The function of the width ratio was set by analyzing the relationship among the width ratio，the distance from the top of slope and failure mode.A new method to determine the ultimate bearing capacity of the strip footing adjacent to slope was then put forward based on the theory of slip line.Finally，the feasibility and rationality of the proposed approach were verified through the comparison with current research results.

Abstract:During the traditional slope stability analysis，soil-rock mixed slope is always regarded as homogeneous soil slope，and rock blocks are neglected.In this paper，a piece of MATLAB code was developed to generate random rock data containing multiple group particle sizes.By using AutoCAD，the generated rock data was conversed to interactive graphics files，which can be imported into Midas for model meshing.Then，the Flac3d model was generated through a Midas_to_Flac3d interface program，and was used to analyze the stability of the soil-rock mixed slope by the method of strength reduction finite difference，which was embedded in Flac3d strength reduction finite difference.With the developed Flac3d model，the influence of some key parameters including the soil and rock interface strength on the stability of the soil-rock mixed slope was analyzed.The results show that neglecting rock blocks may lead to large difference in slope stability evaluation.The plastic zone in the heterogeneous slope is not a similar circular arc as the homogeneous slope，but under the combined effect of a variety of plastic zone propagation routes，it shows a multi-sliding phenomenon.Meanwhile，there is an obvious rounding rock effect through the process，and the sliding length compared with the equivalent homogeneous soil slope has a significant extension.Within the selected scope of the interface parameter changes，the stiffness parameters (normal stiffness and shear stiffness) have little effect on the factor of safety，but strength parameters (friction angle and cohesion) have significant influence on the slope stability.

Abstract:The upper bound theorem and reliability method were utilized to investigate the stability of shallow tunnels excavated in nonhomogeneous and anisotropic soils.The result shows that the effect degree of soil nonhomogeneity and anisotropy is governed by the buried depth of tunnel.When the buried depth is less than 15 m,the self-stabilization capacity of the surrounding rock is poor.As a result,the influence of nonhomogeneity and anisotropy is not obvious,and the supporting pressure tends to increase with the increase of buried depth.However,when the tunnel is deeply buried,greater than 20 m,the self-stabilization capacity of the surround rock is strong.In this circumstance,the supporting pressure varies greatly as the parameters of nonhomogeneity and anisotropy increase.It is also found that the distribution of nonhomogeneity and anisotropy parameters and the variable coefficient have a great effect on the supporting pressure through reliability research,especially when the parameters obey the logarithmic normal distribution.It is suggested that more attention should be paid to the nonhomogeneity and anisotropy of soil mass in the design of shallow tunnel,which would prevent either the increase of construction costs or the collapse of tunnel.

Abstract:Aramid fiber (Kevlar 29) reinforced polymers (AFRP) samples were tested by utilizing a MTS servo-hydraulic high rate testing machine in order to investigate their mechanical properties at different strain rates (25, 50, 100, and 200 s-1) and temperatures (-25, 0, 25, 50, and 100 ℃). The results show that at the same temperature (25 ℃), Young's modulus and tensile strength increase with the increase of strain rate firstly (25 to 50 s-1), and then decrease under the greater strain rate (50 to 200 s-1), while the opposite occurs for toughness. When strain rate is constant at 25 s-1, Young's modulus shows a trend of fluctuation under elevated temperatures, while the tensile strength and toughness show no substantial temperature effect. The failure patterns of AFRP samples were similar at the investigated strain rates and temperatures, and the fracture surfaces were relatively straight. Moreover, Weibull statistics were used to quantify the degree of variability in failure strength at different strain rates and temperatures.

Abstract:A solar-driven thermoelectric ventilator was designed, by adjusting the input voltage of the thermoelectric ventilator to adapt the requirement of fresh air load varied with times.The capacity matching relationships among PV modules, thermoelectric ventilator and battery were analyzed, and the corresponding numerical model was also developed.The working condition of thermoelectric ventilator for an office with a fresh air of 90 m3/h at 8:00 to 18:00 in Beijing from July 21st to August 21st and from January 1st to 31st was simulated.The simulation results show that during the simulation period, the total output of PV modules was 9424 kW, and the total electricity consumption of thermoelectric ventilator was 6435 kW, the maximum power consumption of continuous rainy weather was 119 kW, and the system’s average cooling COP can reach 250 from July 21st to August 21st.The total output of PV modules was 5029 kW, and the total electricity consumption of thermoelectric ventilator was 4054 kW, the maximum power consumption of continuous rainy weather was 151 kW, and the system average heating COP can reach 302 from January 1st to 31st.

Abstract:The cooling characteristics of night ventilation and control method were studied.Two rooms with different functions in Changsha were selected as the research objects,which were simulated by DeST,respectively.By analyzing the relationships among ventilation time,air exchange frequency and exhaust temperature,the cooling characteristics of night ventilation for different buildings can be obtained.The results show that the exhaust temperature varies logarithmically with ventilation time.A method to determine the optimal combination between air changes and ventilation time under taking the same waste heat of room can be obtained when the optimal ventilation energy efficiency is taken as the goal.By using this method,the optimal control of the ventilation system operation can be achieved for the highest ventilation energy efficiency.The method and the results are available for the optimal design and operation of the night ventilation system.