Abstract:Using the hysteresis test results of corroded reinforced concrete columns, the accuracy of the model of corroded steel in reinforced concrete structures was validated. The feasibility of OPENSEES program for the nonlinear dynamic analysis of reinforced concrete structure was verified with the shaking-table test results of reinforced concrete frame. With the program and 30 seismic ground motions selected from the PEER database, a dynamic elastic-plastic finite element model was built. And then, the seismic performance of a corroded reinforced concrete bridge column subjected to far-field earthquake, near-field earthquake with or without impulse action was measured by the nonlinear dynamic time-history analysis in order to study the steel corrosion effect on the structural response under three types of earthquake ground motions. Aiming at the near-field earthquake with impulse action, the Incremental Dynamic Analysis (IDA) was carried out, the IDA curves and the influence of steel corrosion on the seismic performance of the bridge columns were obtained. The results show that near-field earthquake with pulse action has the most significant effect on the structural seismic performance when considering the corrosion, and special attention should be paid to that during structural seismic design.

Abstract:Based on a 7-story reinforced concrete plane frame structure, the guarantee rate and suitability of Pushover analysis method were discussed by statistically analyzing the probability distribution of the performance point of the Pushover analysis method of plane frames with different seismic intensities, site conditions and design earthquake groups in various seismic fortification levels. The results show that Pushover analysis method is a static elastic-plastic analysis method, which is not suitable for evaluating the structural elastic seismic behaviour.

Abstract:Based on the experimental values of the RPC beams prestressed with CFRP tendons of different parameters, the ductility and deformability of these beams were studied, and a corresponding parametric study of the ductility was conducted on the basis of the numerical analysis program. The research shows that the RPC beams are of better deformation capacity than normal concrete beams, and the proposed unloading rigidity formula can be used to calculate the actual unloading curve. It can be concluded from the parametric study that the deformability and ductility of the RPC beam prestressed with CFRP tendons can be enhanced by increasing the ultimate compressive strain of the concrete, the unbonded length of the tendon, the percentage of the compressive reinforcement and the partial prestress ratio, and by decreasing the effective prestress in tendons.

Abstract:In order to investigate the shear behavior of prestressed ultra-high reinforced concrete beams, a total of 11 prestressed ultra-high reinforced concrete beams and 4 prestressed ordinary reinforced concrete beams were tested. The experimental study addressed failure mode, load-delfection curve, ultimate load capacity and the steel strain. The test results have shown that failure mode of prestressed ultra-high reinforced concrete beams is similar with that of prestressed ordinary reinforced concrete beams. Generally, prestressed ultra-high reinforced concrete beams have better higher stiffness and ultimate load capacity, as well as shear ductility. An increase in the shear span-depth ratio or space of stirrups decreases ultimate load capacity. In addition, it has positive effect on the ultimate load capacity for degree of prestress of more than approximately 0.34. A calculating formula for shear capacity of prestressed ultra-high reinforced concrete beams with stirrups was offered. The calculation results agree well with the test conclusions. The current China code (GB 50010-2010) used for the design of prestressed ultra-high reinforced concrete beams is very unstable and the dispersion ratio is high.

Abstract:Two different fillet weld connections and weld throat in tension and shear were tested under dynamic tensile load to study the influence of stress state under impact load on the failure mode, fracture angle and ultimate strength of fillet weld. Compared with the mechanical properties under a static load, the ultimate tension and shear strength increase significantly under a dynamic impact load, which shows obvious strain-rate effect. The dynamic fracture angles of the tensile fillet welds are 45°, which is quite different with static test results. The stain-rate effect of tension fillet weld is more apparent than that of shear fillet weld, and the influence of dynamic increase factor on ultimate strength of fillet weld is in accordance with test results of previous literatures.

Abstract:The aluminum alloy gusset joint has a good global stiffness performance, so the out-of-plane initial bending stiffness interaction of members cannot be neglected. Based on the existing research, the matrix for the bending stiffness of aluminum alloy gusset joint was defined, and the finite element (FE) analysis was developed. Fourteen FE models of aluminum alloy gusset joint were established to discuss the bending stiffness interaction of members, taking into account the thickness of plate, the radius of plate, the height of member’s cross-section and the number of bolts. According to the FE results, the theoretical formulae to estimate the bending stiffness interaction of members on the aluminum alloy gusset joint were proposed. Making a comparison of the theoretical results with FE results, the theoretical results have a good agreement with the FE results, which verifies the applicability of the proposed formulae.

Abstract:Eight concrete filled steel column-steel beam end plate joints connected with blind bolts were tested under axial tension and combined bending-shear static loading. The influence of the binding bars on the integrity of the panel zone of the joints was investigated, and the performance of the blind-bolted joints was discussed. The test results show that the blind bolts have good mechanical properties, and reliable working performance. The binding bars can effectively reduce the tube deformation of square concrete-filled steel tubes and improve the integrity of the joint panel zone. In contrast, binding bars are not so effective in enhancing the performance of joints with circular columns since the circular steel tubes are not susceptible to local buckling. Compared with binding bars, passing-through bolts are more effective in improving the joint performance. Under the combined action of bending and shear, the blind-bolted joints show good deformation capacity. The research results have provided a good basis for the future development of finite element models.

Abstract:Three straight mortise-tenon joints in the base of melon-column were built to study their flexural behavior. The relationships of moment-rotation and failure modes were obtained through monotonic loading tests. The flexural behavior was simulated with finite element software. On the premise of some basic assumptions, the simplified mechanical model was built on the basis of experiments and numerical simulation. Research results show that the main damage type of joints is pulling out, and the resisting torque is mainly synthesized by the vertical load on the top of columns to rotation point. The moment-rotation curve can be simplified as a double broken line model.

Abstract:In order to study the response of the single pile and soil under dynamic loading, the numerical calculation method was adopted to establish the pile soil interaction model considering the basic seismic intensity, then the pile friction force, pile axial force and surface settlement with the change of earthquake duration were analyzed. The results show that 1) negative friction of pile shows the trend of first increase then decrease, and the negative friction mainly appears in the range of 0.35 times the pile length; 2) under the dynamic loading, the pile friction force and axial force are constantly changing, when the earthquake time is 3 s, pile side friction and axial force reach their peak value; 3) as the earthquake continueds, the change of the relative displacement between pile and soil leads to the change of neutral point position; 4) as a result of the dynamic loading, the settlement of the soil increases obviously. Within the scope of the earthquake lasting 0 ~ 10 s, surface subsidence increases rapidly, the earthquake lasting 10 ~ 15 s, the surface subsidence increases slower. When the earthquake lasts until 15 ~ 20 s, the surface subsidence decreases.

Abstract:Based on the explicit dynamic nonlinear finite element analysis method, ANSYS/LS-DYNA was used to analyze the dynamic compaction, and the general steps of explicit dynamic nonlinear numerical simulation method were obtained. Combined with the example of an embankment compaction, a three-dimensional model of the compaction process was simulated to get reinforcement range and fields of stress and displacement. Compared with the field data, this numerical simulation method was proved to be applicable. On this basis, the rammer selection for improving the fly ash embankment in Yueyang by dynamic compaction was studied, and the settlements of soil after dynamic compaction were analyzed and compared, and the results show that the choice of a heavier hammer under the same energy level will have a better reinforcement effect.

Abstract:This paper focused on the macro-meso mechanism of the dynamic response of dynamic compaction in granular soils based on its discrete nature. A three-dimensional discrete element model was first established to simulate the dynamic compaction process by means of secondary exploitation by using the particle code PFC3D and the numerical results were compared with the laboratory model tests. The validation of this numerical approach allowed the extended study of the dynamic response of the tamper and soils and the particles movement. The results show: 1) the dynamic stress propagates within a certain zone and there is a lag in the onset of the peak value along the depth;2) the dynamic stress attenuates more rapidly in the horizontal direction than in the vertical direction; and 3) the particles beneath the tamper mainly move vertically, while the particles below the tamper corners mainly move obliquely downward and the particles side of the tamper move horizontally or obliquely upward. The findings of this study provide a new route for the study of the meso-mechanism of granular soils improved by dynamic compaction.

Abstract:In order to study the wind loads on rectangular high-rise buildings, the wind pressures on seven rectangular high-rise buildings with various length-to-width ratios were tested in a wind tunnel where terrain category B was simulated. The sectional body shape coefficients with respect to wind azimuth and length-to-width ratio were calculated. The distribution of total body shape coefficients along with wind azimuth and length-to-width ratio was studied. Finally, the test results were compared with those obtained from the Load Code. The results show that, when body shape coefficients reach their maximum value, the azimuth is in the windward direction when the wind blows on the long side of the building. However, when wind blows on the short side of the building, the azimuth corresponding to the maximum body shape coefficients is at 20 degrees deviated from the windward direction. The body shape coefficients on the short side of the builing will decrease if the length-to-width ratio increases. The variation of body shape coefficients with depth-to-width ratio obtained from the tests is almost the same as that obtained from the Load Code. However, the variation exists between two sets of the coefficients. When the depth-to-width ratio is less than 1, some of the test data will be larger than the Code data and the maximum data occurs at the depth-to-width ratio of 1∶2. When the depth-to-width ratio is large than 1, the test data is smaller than the Code data.

Abstract:Force tests of tall buildings with openings at its two levels of 0.5H and 0.85H were conducted in the atmospheric boundary layer wind tunnel, and then the wind-induced base forces were obtained with different parameters, such as the dimension, height, location and amount of the openings. The influences on the wind effects of tall buildings with different openings were investigated on the basis of the basement bending moment coefficients and basement first mode aerodynamic force spectrums. The results show that the basement mean bending moment can be reduced efficiently by the opening at along-wind direction, the reduction is more evident for the opening at higher location than that at lower location, and the larger opening also plays more effectual roles for the reduction of basement mean bending moment. The basement mean bending moment at across-wind direction is small, and the value increases in case of large opening, contrary to that for small opening. Furthermore, both of the openings at along-wind and at across-wind directions have influence on the basement fluctuating bending moment. The narrow band frequency with a peak value of 0.12, which is close to the reduced frequency of the vortex shedding, is found for both the cases of large opening and small opening. The difference of power spectrum value is more remarkable in lower-frequency section than that in high-frequency section for different cases.

Abstract:By using the finite element method with consideration of time factor, the vertical differential shortening and member internal forces of steel frame-reinforced concrete corewall structures were analyzed. The studies show that the amount and the involvement time of concrete shrinkage and creep are determined by the time parameters in construction scheme, which change the effect of concrete shrinkage and creep obviously. To reduce the effect of shrinkage and creep, it is a good method to appropriately increase the number of floors of concrete corewall before the steel frame is constructed.

Abstract:Based on the results of continuous observations of the longitudinally connected ballastless track on curved bridges, the time-dependent deformations of vertical temperature gradient in different kinds of weather were discussed. Based on statistics and curve-fitting, raised temperature load models were fit for typical areas in our country. The analysis results reveal that the changing of the temperature in the track structure is fast, the temperature changing value of surface was 16.0℃ in maximum and 8.0℃ in average, the temperature changing value became small, and the time of maximum temperature come late with the increase of distance to surface, and at the bottom of the track structure, the temperature changing value was 1.5 ℃ in maximum, 0.8 ℃ in average, the fitting curve of vertical temperature gradient in longitudinally connected ballastless track on curve bridge can be exponential curve, and the distribution law matches the provisions about the vertical temperature gradient of the code for the design of railway bridges and culverts in China.

Abstract:In order to determine the allowable differential settlement between the bridge and the approach embankment, the vehicle comfort and safety of both the vehicle and the bridge were studied when the vehicle traveled through the transient section. A method based on comfort and safety was then proposed to determine the allowable differential settlement. The average weighted root-mean-square acceleration was used as the vehicle comfort evaluation index, the minimum dynamic wheel load was used as the vehicle safety evaluation index, and the local impact factor was used as the bridge safety evaluation index. The effect of vehicle running speed and differential settlement on the vehicle comfort level and local impact factor was analyzed. The results show that for expressways and first-class highways, the vehicle comfort is a more demanding requirement compared with vehicle safety. For secondary highways, the vehicle comfort is the most demanding requirement among the control indices for differential settlements, followed by bridge safety and vehicle safety. For highways below second-class, the bridge safety is the most demanding requirement, followed by vehicle comfort and vehicle safety. More rational control criteria for differential settlements based on vehicle comfort, vehicle safety and bridge safety can be proposed on the basis of the analysis method of this study.

Abstract:To improve the crashworthiness of bridge piers，a new type of annular anti-collision box with curved-shaped made by steel-polyurethane-steel sandwich plate was proposed. Using the ANSYS / LS-DYNA software with explicit dynamic transient nonlinear, the simulation model of ship collision with pier was established. This paper analyzes the energy conversion between the ship, the anti-collision box, the rubber fender and the pier with the changes of the impact force and the speed of the ship in impact process. It also analyzed the stress and deformation of impact parts of anti-collision box. The results show that the bridge pier's annular anti-collision box with curved-shaped made by the sandwich plate can absorb 70% of the ship impact energy when the anti-collision box is unfavorably impacted, and that the anti-collision box has a saving stiffening plates and brackets, simple structure, and light weight. The study not only shows that the anti-collision box can fully play the impact property and excellent elastoplastic property of the sandwich plate itself, but also provides a theoretical basis for its engineering application.

Abstract:The wind-resistant performance of Jiang-shun Bridge in Guangdong, a cable-stayed bridge with a main span of 700 meters, was investigated by means of wind tunnel tests and computational fluid dynamics method (CFD). The experiments and numerical simulations of the aerodynamic parameters of the main deck and pylon, the wind-induced vibration experiments of the main deck with a sectional model with a geometry scale of 1 to 60, the vortex-induced vibrations (VIV) experiments of the main deck with sectional model with geometry scale of 1 to 25, and the wind tunnel tests of the full bridge aero-elastic model were conducted. The research results have shown that the aerodynamic stability of the bridge during the construction stage or in-service stage is sufficient. The performance of VIV and buffet response under the design wind speed satisfies the demand of the code of wind-resistant design of highway bridges. The VIV amplitudes of the main deck from the section model with geometry scale of 1 to 25 are less than that of the main deck from the section model with a geometry scale of 1 to 60, which indicates that it is conservative to assess the VIV performance of the bridge deck with a section model of conventional scale section.

Abstract:Based on the feature that outdoor environment has a significant impact on the performance of the heat sink of the thermoelectric cooling system, a numerical simulation study was carried out on the heat sink of outdoor electronic devices, which adopt the thermoelectric cooling system. And the optimum thermal conductance ratio of the heat sink was obtained for the design of the heat sink of the outdoor electronic device. The simulation results indicate that the optimum conductance ratio is 0.42～0.54 when the outdoor monthly average temperature ranges from 0 ℃ to 40 ℃. Besides, the total thermal conductance of the heat sink increases from 30 to 50 W·m/K, and the cooling load undertaken by single TEC is from 20 to 30 W, both of which has little influence on the optimal results.

Abstract:The effect of indoor thermal environmental parameters on human body exergy consumption was analyzed from the thermodynamic point of view. The definitions of human body exergy and human body exergy consumption were given, and also the calculation base point of human body exergy. Typical office building environment in winter was selected as research object, and the effect of indoor thermal environmental parameters on human body exergy consumption was quantitatively analyzed. The results show that the change of indoor air temperature or mean radiant temperature has relatively small effect on the human body exergy consumption when indoor air relative humidity ranges from 10% to 50%, and the change of indoor air relative humidity has relatively large effect on the human body exergy consumption when both indoor air temperature and mean radiant temperature are less than 20 ℃.

Abstract:To understand the sustainable development ability of a regional eco-economic system, this paper constructed a DEAHP model and an evaluation index system by combining the connotations and characteristics of the internal structure of a regional eco-economic system. Furthermore, we evaluated the sustainable development level of both provincial and regional eco-economic systems from 2007 to 2012 in China. The results showed that the degree of the overall order in China increased monotonically and was relatively low. In addition, the results show that, for the three regional eco-economic systems in China, the eastern region differs remarkably from the western region but two neighbouring regions are relatively closer. The results are very much the same at the provincial level. Also, at the provincial level, the sustainable development ability of a provincial eco-economic system is positively correlative with the development of local economy. This paper presents a feasible research framework, which uses a DEAHP model to evaluate a regional eco-economic system and provides theoretical and practical guidance for the sustainable development of regional eco-economic system in China.

Abstract:To address the uncertainty of the target weight in assessing science and technology awards, the Random Forest Weighting Method was proposed. Reliability analysis was used to calculate the generalization error of expert evaluation data，and according to the minimum error rate, to obtain the evaluation project of each evaluation index weight and to reduce the impact of subjective weighting.Consistently reliable information, inconsistently reliable information and net reliable information were introduced. An improved ELECTRE-Ⅲ method was put forward to solve the problem of expert evaluation data for order variability. A specific number to measure a certain degree of an evaluation project is superior to other evaluation project. Empirical evidence shows that the combination of the Random Forest Weighting Method with the improved ELECTRE-Ⅲ method not only improve the accuracy and reliability of weight estimation , but also solve the problem of inability to set threshold level and rank completely, leading to more scientific, objective and reasonable evaluation results.