Abstract:For structure optimization of a groove type condenser,a three-dimensional finite element model of the groove type condenser was established based on MIDAS/Gen according to the groove type condenser devices located in Zhangjiagang testing ground. The method of Lanczos modes calculation was used in the model,the modal analysis was conducted under the conditions of different angles,and the structural mode characteristics of the groove type condenser were received under different working conditions. The dynamic characteristics were tested on the devices by arranging the measured points on different parts of the structure and placing sensors at the center of condensers. The dynamic signal acquisition system was used during the field measurement,the testing equipments and devices such as sensors and data acquisition instruments were used to capture the valid data of each measured point. The dynamic characteristics of groove type condenser were then acquired by processing the original data through the acquisition system. For verification of the analysis method,the finite element model was compared with the field measurements. The comparison results show that the three-dimensional finite element model can simulate the existing groove type condenser well,and it can be used in its static analysis and structure optimization analysis. In addition,the finite element modal can provide a scientific reference for further improvement on the concentrated effect of groove type condenser group and cost reduction.

Abstract:A 240 m-height RC chimney was chosen as the research object. Composite shell element was adopted to establish the nonlinear analytical model by using the finite element software ABAQUS. In order to perform the incremental dynamic analysis considering the uncertainty of the ground motions，20 ground motion records were selected based on the matched-spectrum principle. The peak ground acceleration and maximum strain were selected as the intensity measure and engineering demand parameters，respectively. Based on the material strain of concrete and steel rebar，the limit values of four damage states were defined. The base excited by the ground motion has seven different angles during incremental dynamic analysis. Combining with the response of structure obtained by incremental dynamic analysis，the vulnerability was calculated by the curve fitting method. The seismic fragility and collapse probability curves of high-rise RC chimney structures under different ground motions were then obtained. The results show that when the PGA is smaller than 0.2 g，the critical input angle is approximately 75°~90° and the complete damage probability increases about 1.5% considering directionality of three-directional earthquake. When the PGA is bigger than 0.2 g，the critical input angle is 45° and the complete damage probability increases about 2.4%.

Abstract:To solve the problem of seldom use of isolation technology in super high-rise buildings as well as the restriction on the tensile capacity of isolation bearing and structural height-width ratio limitation，in this paper，the combined isolation layers consisting of lead rubber bearings and elastic sliding bearings were set at the bottom of the sub-structures in the new mega-sub structure system. An experimental model of mega-sub structure was designed and manufactured，which included three mega floors. Shaking table tests of the uncontrolled and controlled mega-sub structure under near-fault and far-fault ground motions were carried out. Vibration control effects of combined isolation layers on the seismic vibrations of main-structure and sub-structures and the influences of near-fault ground motions were studied. The results show that the combined isolation layer at the bottom of sub-structure is equivalent to a tuned mass damper for the main-structure，and it has obvious damping effect of TMD on the seismic reactions of main structure，while it is equal to a base isolation structure for the sub-structure itself，and it has significant isolation effect on the seismic responses of sub-structure. Seismic reactions of the main-structure and the sub-structures under near-fault ground motions are larger than that under far-fault ground motions due to the pulse effect.

Abstract:In order to improve the bearing capacity and ductility of square concrete-filled steel tube (CFST) column，this paper proposed a new structure scheme，adding ribs at the end of CFST column.Three CFST columns with end ribs were designed and produced.Pseudo static test was conducted，and seismic behaviors including the bearing capacity，hysteresis curves，skeleton curves and displacement ductility were obtained.Compared with the conventional CFT columns，experimental results indicated that the hysteretic loop curve of the test specimens dissipated large energy，and the decline of the skeleton curve was not significant.The ultimate displacement increased obviously by 44.4%，65.3% and 29.3%，respectively.The ductility increased by 27.0%，51.3% and 6.7%，respectively.The CFST columns with ribs exhibited good energy dissipation capacity and their seismic performance was significantly improved with larger ductility.

Abstract:To investigate the damage of RC frame-shear wall structures under earthquake load，a member importance index based on the generalized structural stiffness was introduced. First，seismic elastic-plastic analysis was made by using software perform-3D. Meanwhile，the rules of energy distribution were obtained for RC frame-shear-wall structures. Based on the deformation and hysteretic energy，a seismic damage model with double variables was built to evaluate the member damage，and floor damage model was developed to evaluate the floor damage based on member importance index. Finally，floor damage degree can be evaluated by comparison between damage index under different peak ground acceleration and index ranges. The results showed that the method reflected not only the member damage degree but also the member importance index having effect on floor damage，and the method was applicable to damage assessment for RC frame-shear-wall structures.

Abstract:The influences of cement-based material (such as fine aggregate concrete) strength，prestressing，additive admixture and other factors on the friction performances of the integral prefabricated prestressed slab-column joint structures were analyzed through experimental study on 6 joints. The difference between the slab column joints with and without fine stone concrete cement material was also compared. The results show that fine stone concrete at the slab column joints can significantly improve the friction performance. The friction performance was increased by more than 35% when compared with that of the joint specimen without filling materials. Cement material strength，prestress and additive admixture can affect the friction performance of the node to various degrees. When the cubic strength of the fine aggregate concrete increased from 30 MPa to 40 MPa，the friction performance at the joint interface increased by about 9.8%. When the prestress increased from 300 kN to 450 kN，the friction performance of the joint interface increased by around 55.1%. The expansion agent can also improve the friction performance of the joint interface，but the effects are just a little.

Abstract:In order to study the ability to resist lateral force of nuclear shielding workshop under earthquake action，the low-cyclic loading tests of nine 1/5 scaled composite shear walls with double steel plates and filled concrete were carried out. This paper studied the influence of several parameters such as stud space，thickness of the palate and stiffener on initial lateral stiffness of specimens. The results showed that the initial stiffness of composite shear walls increased with the thickness of steel plates and stiffening rib setting，but the factor of stud space had no obvious effect on it. The calculation formula of initial stiffness of composite shear walls with double steel plates and filled concrete was derived by using unit load method，theoretical hypothesis and simplified precondition. The calculation value was consistent with the experimental value. Moreover，the change process of lateral stiffness of shear wall specimens under cyclic loading was studied and it was found that the changing degree of the stiffness was different in the different stages of the change process of lateral stiffness.

Abstract:Quasi-static uniaxial tensile behavior of carbon textile reinforced cementitious composites (TRC) was studied,and the factors of reinforcement ratio and short steel fibres and prestress were considered in the tests. The test results showed that the efficiency of carbon fibers decreased with the increase of textile ratio for the TRC plates without steel fibres during the tests,the textile layer and matrix layer were gradually separated,and debonding failure of TRC plates occurred ultimately. Applying prestress force to the textile can increase the initial cracking stress of TRC plates,and thus improved the normal service life of TRC components. Adding steel fibres in TRC plates was helpful to improve the interfacial properties,and thus both the tensile strength and ultimate strain of the plates were enhanced. Compared with the application of prestress to the textile,more pronounced enhancements of mechanical properties were achieved by the addition of steel fibres. Applying prestress to the textile and adding 1% of steel fibres in plates at the same time can significantly improve the efficiency of carbon fibers. Eventually,carbon fibers were completely broken when the plates were damaged.

Abstract:On the basis of freeze-thaw damage theories，the freeze-thraw damage pattern and feature of ordinary Portland concrete (OPC) were studied under the aircraft de-icer with ethylene glycol. The micro-phase compositions of specimens were analyzed by X-ray diffractometer，microstructure was observed by scanning electron microscopy and Micro area element was analyzed by energy dispersion X-ray. The main results were remarked as follows: The frost resistance of concrete under the action of lower concentration of EG was more serious than that of water，while the freezing and thawing damage in higher concentration of ethylene glycol was slightly lower than that of water. The lower concentration of aircraft deicing fluid results in more serious damage to the concrete. The freeze-thaw damage of OPC with low concentration of ethylene glycol was mainly the surface spalling failure，and the mass loss reached the standard of failure firstly. However，when immersed in high concentration of ethylene glycol，the freeze-thaw damage of OPC was that the relative dynamic elastic modulus first came up to the failure stand，which was mainly embodied in severe spalling at the ends. In a whole，the freezing and thawing damage was a physical damage mechanism. No new substances were formed during the freezing and thawing experiment in EG. The hydrated calcium silicate gel and crystal of calcium hydroxide were not changed in cement. The freezing thawing damage mechanism of OPC in EG solution was the same as that in water，which was mainly dominated by the freezing pressure.

Abstract:In order to investigate the typhoon-resistance of wind turbines with different towers,four wind turbine integration models with different forms of towers were built by Abaqus finite element software and Autoregressive (AR) model was used to simulate the fluctuating wind for modal analyses and typhoon time-history analyses. The results show that the natural frequencies of wind turbines are greatly affected by wind rotor and nacelle. When the typhoon wind speed increases,the maximum along-wind displacement of the steel conical-cylindrical tower climbs linearly,while those of the other 3 towers show a significant nonlinear growth. As a lightweight flexible structure,the steel tube lattice tower exhibits the greatest dynamic response,and the steel conical-cylindrical tower exhibits the second one. Because of the considerable stiffness and weight,the displacement response of the reinforced concrete conical-cylindrical tower is the minimum,and the typhoon-resistance capability is the best.

Abstract:The existing researches for wind load characteristics of the downburst mainly concentrated on stationary impinging jet model，but rare investigation was for time-varying characteristics and the impact of mountain terrain. In this paper，based on the impinging jet model，the decay function was brought in to make the inlet wind velocity more close to the decay process of the whole life cycle of the thunderstorm，and the wind load characteristics of typical high-rise buildings on the top of the slopes and the characteristics of the thunderstorms on the slope landforms were analyzed by transient large eddy simulation (LES). The results show that the transient simulation of LES is more reliable，the wind speed fluctuation of the unsteady shock wind field is larger，and the variation law is similar to the measured wind speed curve. The unsteady wind load shows strong unsteady characteristics，greater fluctuations and rapid attenuation with wind speed. The wind load fluctuation of unsteady shock wind is wide and has strong potential to damage，the wind load on the sloping terrain is generally smaller than that of the flat ground，and the influence of the slope terrain on the upper part of the building is obviously higher than that of the bottom. With the enlarging of slope angle，the upper wind load gradually decreases.

Abstract:This paper proposed a novel mechanical model of nail joint restoring force with seven model parameters were based on low-cycle and repeated tests of light wood structure nail joints. This model considers different pinch points and slip effect in both positive and negative directions. Model parameters were identified by using the Bayesian method.The results show that the accuracy of Bayesian identification method relies on the quality of raw data. The result of the most probable value and the associated covariance matrix can be determined and used to the calculation of nail joint with the same conditions. The model response obtained from the result of parameters identification is in good agreement with the experimental results. The restoring force model proposed in this paper provides a reference for future nail joints analysis. Furthermore，Bayesian method is extended to parameter identification of nail joints restoring force，providing a novel way to investigate nonlinear hysteretic analysis of light wood structures.

Abstract:It is very important to explore the damage evolution mechanism of wood under tensile loading at meso-scale，which is the foundation of establishing the damage constitutive model. In this paper，the component characteristics of wood at both macro and meso-scale were analyzed，based on the assumption that wood is equivalent to numerous tension fibers in parallel and every tension wood fiber is equivalent to an elastic brittle tensile micro-spring. The damage evolution equation was derived based on the assumption that the ultimate strains of tensile micro-springs are random variables that obey some form of distribution. Based on the correct setting of acoustic emission parameters PDT，HDT and HLT，the parameters of the ultimate strain distribution function were obtained by tensile acoustic emission tests on Northeast Larch wood specimens along the grain during the failure process. Furthermore，the damage evolution model was established.The analyzing results show a good coherence between the acoustic emission accumulative events and the damage evolution，and the acoustic emission tests are available for the damage assessment during the wood longitudinal tensile process.

Abstract:According to the construction and loading features of Tibetan ancient timber beam,a nonlinear spring was added at the end of the beam and the simplified mechanical model of temperature effect on the timber beam was established. Considering the second order of the counterforce of beam end,a theoretical model of the strain in the grain direction of the mid-span beam bottom under temperature effect was proposed. The strain in a temperature cycle was divided into four parts for calculations. A timber beam of a Tibetan ancient building from a monitoring system was employed as a calculation example. The results show that the strain returns to the initial value in a temperature cycle,while the curves of the temperature rising stage and temperature decreasing stage are not coincident but divided into two parts. The calculated strain curve matches well with the measurement. Finally,the parameter analysis of the structure parameters affecting the strain variations was proceed,and the results show that the different starting temperature makes no difference for the analysis results. Elasticity module is the most sensitive parameter,while the tension and compression stiffness of the dovetail joint is the least sensitive parameter.

Abstract:The vertical bending stiffness assessment of the cable-stayed bridge has been a hot research issue in the dynamics of bridge. Based on the mechanical characteristics of stay cable supporting deck，a new evaluation method was proposed for the vertical bending stiffness of a floating single-tower cable-stayed bridge. Firstly，a new dynamic model (i.e.，triple-beam with discrete springs) of the floating single-tower cable-stayed bridge was proposed and its corresponding dynamics theory was derived. In the proposed model，the stay cables were simplified as springs without mass and the single-tower was regarded as an Euler-Bernoulli beam with consideration of axial force. At the same time，the deck was divided into two segments at its intersection with tower，hence the deck was regarded as two Euler-Bernoulli beams. The eigenvalue and eigenvector of the dynamic system were then solved by the transfer matrix method，which was used for the evaluation of vertical stiffness of the floating single-tower cable-stayed bridge. Finally，the case study and its comparison with results obtained by the finite element method show that the evaluation method proposed is of high precision and efficiency，and can be used for the calculation and stiffness evaluation in engineering design.

Abstract:Based on the developed three-segment model with inner dynamometric suspension frame，the vortex-induced vibration (VIV) and the corresponding vortex-induced forces (VIF) of preliminary design deck of a long-span cable-stayed bridge were measured through wind tunnel test with aeroelastic section model. Through the analysis of VIV under 0° and +3° wind attack angle，the dynamometric model was proved to be effective for measuring aerodynamic forces on bridge deck. In addition，the recorded displacements and forces of VIV under different wind attack angles were compared，and the varying curves of VIV frequency，phase difference between force and displacement as well as the work applied by VIF in lock-in range were also discussed. The results show that the dynamometric model can measure the aerodynamic forces simultaneously when the model is vibrated. Furthermore，for the lock-in range，the VIF frequencies were the same as displacement frequencies，and the phase difference between VIF and displacement increased with the wind speed growth，while the work applied by VIF demonstrated the trend of increasing firstly and then decreasing.

Abstract:This paper proposed an identifying method of scour condition of cable-stayed bridge pylon by tracing the dynamic index. Firstly the quantitative relationship between the identification index and scour depth is theoretically simulated by a series of parametric study. Once the identification index is obtained based on the monitored dynamic performances during the bridge routine measurement,the scour depth of pylons at the moment of monitoring can be directly deduced by the pre-obtained quantitative relationship. In order to investigate the feasibility of this method,two identification indexes such as the natural frequency of bridge and deformation of modal flexibility were proposed. As a case study,the relationships between these two identification indexes and scour depth of pylon were carefully analyzed based on Finite Element (FE) model of Ningbo Zhaobaoshan bridge (a cable-stayed bridge). The results indicate that the pylon scour depth of cable-stayed bridges can be quantitatively identified by tracing the identification indexes. Especially,the indexes including the deformation of modal flexibility built by the vibration modes of vertical bending of girder and transverse bending of pylon show much more sensitive and better identification effects than those of other indexes. It can be concluded that the proposed identifying method for pylon scour depth by tracing the dynamic index has the advantages of accurate calculation logic,convenience,and good economical efficiency without underwater operation. The scour depth can be correctly predicted as long as the dynamic performances of bridges are accurately measured and traced.

Abstract:The existing computational methods of displacement release coefficient are too complex. Based on quadratic regression orthogonal design，a construction method of displacement release coefficient formula was given，and a series of numerical experiments of a circular tunnel in hydrostatic stress field were carried out by the above method. The regression equation of displacement release coefficient was established，and the sensitivity of parameters was determined. Through analysis of numerical examples and a case history，the equation was proved to be reasonable and effective. The results indicate that for different levels of surrounding rock，the effect of the same factor on the displacement release coefficient of the tunnel face is different. Stress level，disturbance of rock mass，GSI，H-B material constant and Poisson's ratio have a great influence on the displacement release of tunnel face，while the intact rock strength and deformation modulus have little influence.

Abstract:In order to investigate the interaction between GFRP pile and soil as well as dynamical mechanics effect in driving pile，model test of jacked GFRP piles was conducted，and the heave of topsoil and radial squeezing pressure were analyzed. The results show that the heave of topsoil reaches the maximum value when the radial distance is equal to 1.8 times the pile diameter. The maximum value decreases with the increase of the depth of piling and eventually stabilizes at about 5 percent of pile diameter. Radial squeezing pressure in a certain depth first increases and then decreases with the increase of the depth of piling，and reaches the maximum value when the depth of piling is equal to the depth of measure point. The maximum value of radial squeezing pressure，Pm，decreases with the increasing radial distance. When the radial distance increases to be three times of the pile diameter，Pm reduced to thirty percent of P mm (i.e.，the peak value of Pm) or less.P mm appears at the lower part of the pile，whose value is roughly in proportion to the pile diameter.

Abstract:Based on fictitious soil pile and generalized Voigt model，dynamic equilibrium equations of pile and cushion cap were established in the vertical vibration，displacement and velocity solutions of cushion cap were obtained on frequency and time domain，and the influence of pile subsoil on the vertical dynamic characteristics of cushion cap was studied. The results show that under the same initial displacement condition，the deeper thickness of single-layer pile subsoil results in the smaller displacement，velocity amplitude and vibration frequency of cushion cap，but the resonant frequency is the same. In the case of weak substratum，the deeper thickness of substratum and the worse substratum results in the smaller displacement and velocity amplitude of cushion cap. Finally，the comparison results with single Voigt model of pile subsoil and actual engineering curves show that fictitious soil pile model can accurately simulate the role of weak substratum and the calculation is more close to the measurements.

Abstract:In order to investigate the performance of castor oil-based bioasphalt blended asphalt mixture，design of AC-20C blended asphalt mixture with 5 different percentages of bioasphalt was conducted. Performance tests were then carried out on the specimens with optimum asphalt contents of respective percentages of bioasphalt. Based on the test results，the properties such as high temperature stability，moisture damage resistance，low temperature cracking resistance，and pavement structure design parameters were analyzed. The analyses indicate that with increasing percentage of bioasphalt，the high temperature stability，moisture damage resistance and compressive resilient modulus of the blended asphalt mixture decrease，but they satisfy the requirements of JTG F40-2004 within a certain range of percentage. The moisture damage resistance is significantly improved by adding hydrated lime. With increasing percentage of bioasphalt，the indirect tensile strength of the blended asphalt mixture decreases to the minimum value and then increases slightly，while the low temperature cracking resistance of the blended asphalt mixture increases. Hence，the use of castor oil-based bioasphalt as partial replacement to petroleum based asphalt in asphalt mixture is feasible.

Abstract:Layer-parallel direct shear test was carried out on the double-layered asphalt concrete specimens with geotextile interlayer. The influence significances of temperature and deformation rate on the bond failure behavior of geotextile interlayer in asphalt overlay were analyzed by using the index of interlayer shear strength based on ANOVA and multiple comparing methods. The mathematical relationship among temperature，deformation rate and interlayer shear strength was then derived from an exponential function. Moreover，the sigmoidal master curve of interlayer shear strength was built based on the time-temperature superposition principle (TTSP) and the equivalent character of time-temperature for interlayer shear strength was also validated. The results showed that the influences of temperature and deformation rate were significant. The interlayer shear strength was lower when the temperature increases or deformation rate decreases. Furthermore，exponential model was used to predict the interlayer shear strength in laboratory，and the simulation results agreed well with the experimental results. The change tendency of the interlayer shear strength was showed in a broader range of deformation rate by using the sigmoidal master curve. The interlayer shear strength of specimen with geotextile interlayer had equivalent character of time-temperature which was validated by the consistency of shift factors for creep compliance and interlayer shear strength.

Abstract:The energy consumption,exergy consumption,CO 2 emissions and cost of five public buildings in Hunan area in its life cycle were calculated based on life cycle theory and exergy method,taking into account the formation of building envelope. On this basis,two indicators including the building exergy-energy ratio and greenness were introduced. The greenness of each building was obtained by analytical hierarchy process. The comparison of the greenness indicators shows that office buildings are much better than commercial buildings in terms of greenness. Comprehensive comparison of the two indicators illustrates that there is an optimal range for exergy-energy ratio. The greenness indicator takes into account the building life cycle resources consumption,cost input and environmental impacts,and the exergy-energy ratio demonstrates the use of high quality energy. Therefore,these two indicators can serve as a supplement to the passive energy saving clauses in the existing sustainable building assessment systems.

Abstract:This study focused on thermal comfort of subjects with radiant cooling workstation and desktop fan in hot-humid environments. Twenty-four human subjects participated in the experiments and reported their thermal sensation，thermal comfort，thermal acceptability and thermal preference in the hot-humid environments at 26，28 and 30 ℃ in an environmental chamber. The obtained results show that radiant cooling workstation and desktop fan significantly improved the thermal comfort of subjects in the hot-humid environments，but the effect was not obvious at 26 ℃. Subjects can still well maintain the neutral thermal sensation condition although indoor environment was as high as 30 ℃ and the relative humidity was 80%. Therefore，radiant cooling workstation and desktop fan can extend comfortable temperature range in summer. This study provides a new way for maintaining comfort in non-neutral environment and saving energy in buildings.

Abstract:Aiming at the heating problem of hot-summer and cold-winter areas，the experiment system of air source heat pump and capillary floor radiant heating was established. The characteristics of indoor temperature，the walls temperature and indoor thermal environment were tested and analyzed under different water supply temperatures of 40 ℃，37 ℃，35 ℃，33 ℃，30 ℃. Under the condition that the cover area of capillary radiation over the ground is 50%，spacing of capillary is 20 mm，the filled pomegranate concrete thickness is 50 mm，the surface covered with the wooden floor thickness is 12 mm in Chongqing，the experiment results show that the indoor temperature is stable at 18.73 ℃，18.06 ℃，17.03 ℃，16.09 ℃，and 15.28 ℃，the indoor thermal sensation (PMV) is -0.65，-0.82，-1.09，-1.31，and -1.44，and the percentages of dissatisfaction (PPD) is 14%，19.08%，30.18%，40.71%，and 47.39%，respectively. The maximum temperature difference in the vertical and in the horizontal is 0.39 ℃ and 1.12 ℃ in the rooms with different conditions. When the water temperature is equal or greater than 33 ℃，it satisfies the requirements of indoor temperature ，and when the water temperature is equal or greater than 37 ℃，the indoor PMV and PPD meet the evaluation of thermal comfort standards. In addition，the distribution of indoor temperature is uniform under different conditions.