Abstract:The features of seismic analysis of long-span structures and the three methods which are commonly used in analyzing the seismic response of long-span structures under multi-support excitations are briefly stated, and then the research developments of multi-support response spectrum method at home and abroad are presented in detail. Finally, some problems needing further investigations are proposed.

Abstract:The method for forming damping matrix in explicit algorithm of LS-DYNA in the analysis of seismic response of soil layer was studied in this paper. First, based on the assumption of mass-proportional damping matrix, the influence on the damping ratio of each mode was discussed. Then the analysis methods of time domain and frequency domain were applied in the seismic response calculation of three different types of soil layer. Through the comparison of calculation results between time domain and frequency domain, the effects on calculation results by using mass-proportional damping matrix were explored. Finally the determination of damping coefficient of the mass-proportional was proposed. Only when the seismic displacement reaction of soil layer is calculated or when the fundamental frequency of soil layer is higher than the input seismic wave excitation frequency of the under lying bedrock to calculate the soil seismic acceleration response, it is feasible to apply the fundamental frequency of soil layer to determine the mass-proportional damping coefficient. When the fundamental frequency is close to and especially much lower than the excitation frequency of input seismic wave, substituting the arithmetic mean of soil layer fundamental frequency and response spectrum peak frequency of input seismic wave for the soil layer fundamental frequency is recommended to calculate the mass-proportional damping coefficient. This method can effectively improve the calculation accuracy.

Abstract:This paper analyzed the seismic force modification factor R of strength degrading modified elastic-perfectly plastic (EPP) model, bilinear elastic (BIL) model and shear-slipped elastic-plastic (SSP) model for different site and ductility factor. The system coefficient spectra of base shear were constructed to analyze the influence of the degradation of strength on seismic force modification factors. An ideal elastic-plastic model is proposed which is equivalent to the degradation model. Results reveal that the strength degradation has almost no influence on the R spectra of BIL and SSP model, but for modified EPP model, its influence increases with the degradation and cannot be neglected. When taking the strength degradation to define the ductility factor in practice in modified EPP model, it is necessary to adopt a ductility-definition-related strength reduction factor. For the strength degrading system, the strength demand and the deformation-capacity demand are found to be αEK times of the ideal elastic-perfectly plastic model.

Abstract:Based on the discrete element method, a numerical simulation method of the vibration control effects of particle dampers is established, and the method of determining the corresponding system parameters is introduced. In this method, a suitable particle damper system is modeled, a reasonable time step is determined, an efficient contact detection algorithm is adopted, and the interactions between particles and the container are represented. A shaking table test of a multi-storey frame with particle damper system is carried out. Compared the test results and the simulation results, they are agree well with each other, which demonstrates that the proposed numerical simulation method can yield reasonably accurate estimates of control effects of particle dampers.

Abstract:This study investigates the use of a kind of rolling-balls tuned mass dampers as an effective method to reduce the wind-induced vibration of wind turbines. The noval damper is characterized by single or multiple steel balls rolling in a spherical bowl. A 1/20 scaled experimental model was designed to investigate the performance of the damper through shaking table tests. The equivalent ground acceleration was inputted to obtain the equivalent dynamic response under different wind load cases. A series of forced vibration experiments were performed on the shaking table. The results indicate that the damper can effectively improve the damping capacity of the model. The standard deviations of the base moment and the top displacement were reduced 20%-46%. The damper is very simple in the construction and has a good economic performance, so it is a feasible means to suppress the wind- induced vibration of wind turbines.

Abstract:In particular, 24 push-out tests were carried out in Tongji University to investigate the performance of the shear stud at elevated temperatures. Three different floor arrangements including solid slabs, composite slabs with trapezoidal steel sheeting parallel to the steel beam and composite slabs with trapezoidal steel sheeting perpendicular to the steel beam, were considered in tests. It was observed in the test that the predominant mode of failure for the solid slabs and profiled slabs with trapezoidal steel sheeting parallel to the steel beam was headed stud shear failure while the predominant mode of failure for the profiled slabs with trapezoidal steel sheeting perpendicular to the steel beam was concrete cracking failure at low temperatures and stud shear failure at high temperatures. Also, the ultimate load in solid slabs was generally higher than that in the profiled slabs. In addition, the ultimate load and stiffness decreased with increasing temperature for all slabs. By analyzing the test results, an empirical equation was proposed to calculate the shear capacity of studs.

Abstract:Based on continuum mechanics and the principle of virtual displacements, incremental updated Lagrangian formulation (U.L.) were presented. The large displacement stiffness matrix was considered in U.L., which was rectified to be symmetrical matrix. According to the incremental updated Lagrangian formulation, small strain, large displacement, finite rotation of three dimensional fiber beam element tangent stiffness matrix was developed. Considering the nonlinear constitutive relationship of composites, large displacement and finite rotation, a new type of tangent stiffness matrix of the beam element was presented. According to the basic assumption of plane section, the displacement field of an arbitrary fiber was presented in terms of nodal displacement, and shear deformation effect was not taken account. Furthermore, a nonlinear finite element method program has been developed and several examples were tested to demonstrate the accuracy and generality of the three dimensional fiber beam element.

Abstract:In this paper, wind profiles of typhoon ‘Muifa’ are analyzed based on the long time measured data recorded respectively at 10,20,30 and 40 meters height levels above the ground in Pudong area Shanghai. The height of neutral ABL increases with wind speed. The average height of neutral ABL during typhoon ‘Muifa’ is 2063m by calculation, which greatly exceeds the gradient height(350m) recommended by Chinese National Load Code(GB50009-2001,2002) for open terrain. The stability parameter z/L is almost in [-0.1, 0.1] when the wind speed becomes high, which means near-neutral flow. Measured mean wind speed profile agrees well with the power law, the log law and Deaves-Harris ABL model. Based on expression form in ASCE7-10, the fitting equations of turbulence intensity profiles in longitudinal, lateral and vertical directions are presented. Finally, the formulas for gust factors are also derived using curve-fitting technique, which can provide reference for engineering designing.

Abstract:Shield tunnelling will inevitably lead to the vertical deflection of existing pipelines. Based on a Pasternak-type two-parameter elastic foundation model，a two-stage analytical method for estimating the vertical deflection of existing pipelines is presented in this paper. With respect to the first stage, the Loganathan and Poulos analytical solution is used to estimate the free-soil settlement caused by shield tunnelling at the existing pipeline's position; in the second stage, the free-soil settlement is imposed to the existing pipeline, which is simplified as an infinite beam on a Pasternak foundation. The governing differential equations of the pipe are formulated and analytically solved, and the deflection and internal forces of the pipeline are obtained. The effects of the lateral soil beside the pipe are considered and more reasonable results are obtained. Foundation model parameters are determined by the simplifying elastic continuum method. The superiority of the Pasternak foundation model, compared to Winkler foundation model, is qualified by comparing results with numerical results. The accuracy of the proposed method is verified by a good agreement with the engineering case study.

Abstract:Based on the upper-bound limit method, theoretical formula of the minimum support pressure to maintain the face stability of the homogeneous soil tunnel under high-water level condition are deduced for the first time. Taking advantage of the soil thickness-weighted average method, the multi-layered soil parameters and the water pressure are to simplify the analysis, then the theoretical formula above can be applied to evaluate the face stability of the multi-layered soil cross-river tunnel and estimate the support pressure of the cross-river tunnel project. With the Shanghai Yangtze River Tunnel and the Nanjing Yangtze River Tunnel for example, limit support pressures of face were calculated by using the theoretical formula, and the calculated results has achieved a good agreement with the previous studies and engineering practice.

Abstract:This paper suggests a set of analytical solutions to study pore pressure distribution and long-term settlements of ground and tunnel due to tunnel leakage. The analytical solution is obtained based on the conformal mapping of the complex variable methods. The accuracy of the analytical solution is verified with numerical solutions. The results indicate that the relative permeability between soil and lining is essential for water inflow. The water inflow into the tunnel increases with the decrease of the relative permeability of soil and tunnel lining. The settlements of tunnel and ground increase linearly with the increase of water inflow. Therefore, the leakage of the shield tunnel should be monitored carefully and the corresponding waterproof measures should be adopted for operation tunnel to control the tunnel deformation and ground settlement.

Abstract:Based on 8-DOF driving simulator, the effects of lane width, lane position and shoulder width on driving behavior in urban underground road have been examined. Participants drove in a separating one-way three-lane of underground road with a driving simulation. Speed, lane deviation and subjective perception were collected. The result shows that lane and shoulder width have significant effects on objective and subjective measures. The effect of lane width is greater than shoulder width. An interesting finding is that the inconsistence of the driving behavior measures with subjective perception of the lane position. These findings provided support for amending the current design specifications of urban underground road, such as relationship between design speed and lane width, speed limit, combination form of lanes.

Abstract:This paper points out that the tranditional axial model does not consider the key factor of the propertied of buildings around subway stations, however, different buildings have different generation and attraction of pedestrian activities. Then the paper selects building height and building density as two indexes to modify the axial model. According to the difference of building density of 500m radius area around a subway stations’ entrances and the domestic and foreign relevant rules for high-rise building regulations, the paper draws the conclusion of the applicable condition of the modified model. At last this paper compares the modified model’s applicability of subway stations in Shanghai and Nanjing, and finds out the accuracy of modified model is both higher than 91%, so the conclusion is drew that the modified model and applicable condition can be widely-used in different metropolis. This research provides theoretical support to the design of passageway width, fare gates number, parking facilities and bus station layout outside the subway station.

Abstract:The problem of pavement rutting is getting worse, which reduces pavements’ life and greatly effects driving safety. Through comparative analysis, a single penetration repeated shear test (SPRST) for a research on asphalt mixture permanent deformation was put forward. Many SPRST tests on different load levels were did with four kinds of most commonly used asphalt mixtures in the upper and middle layer of asphalt pavements. Some conclusions were the followings. (1) The three-stage permanent deformation behavior of asphalt mixtures on loads could be got by SPSFT. (2) The bigger the load was the faster permanent deformation of asphalt mixtures increased and the smaller the shear fatigue life or the flow number were. Large load (≥1.3MPa) made the large deformation with not large load cycles and the mixture broke; but the smaller load (≤1.1MPa) got very slow increase of the deformation, which was stably in the second stage of three-stage permanent deformation and didn’t broke. (3) The asphalt mixtures with bigger shear strength had a greater ability resistance to shear deformation. Mixtures with modified asphalt had a greater ability resistance to shear deformation than with conventional asphalt. (4) Load stress levels had an equivalence to load cycles.

Abstract:Softening point and flow test results of twenty hot-applied sealants were analyzed. The results showed that softening point and flow value were related (significance level p<0.01), thus flow test can be abandoned. Cement concrete specimens and asphalt concrete specimens were conducted by bond test, respectively. Two-factor analysis of variance showed cement concrete specimens and asphalt concrete specimens didn’t have significant effect on bond test (significance level p>0.05). Asphalt concrete specimens were recommended to use in bond test. Asphalt pavement crack movements were observed, according to the observations, test temperature and extension requirements of bond test for four types sealants were: 0℃ and 25%, -10℃ and 50%, -20℃ and75%, -30℃ and 150%, respectively. The study provides a technical basis for the revision of the transportation industry specification for hot-applied sealant.

Abstract:Many scholars have studied the fatigue performance of orthotropic steel bridge decks and got fruitful achievements, but so far, few scholars have discussed the influence of pavements’ temperature on fatigue life of steel bridge deck. In this paper, actual stresses of the steel bridge deck were measured through fatigue test with full-scale model in different temperature conditions. The results showed that stiffness of the asphalt mixture reduced quickly with the increasing of temperature, and resulting in rapid increasing of stresses of orthotropic steel bridge deck under the pavement. The fatigue damage of the steel bridge deck at high temperature(about 55℃) condition is approximately 21 times at room temperature(about 10℃) under the same load conditions.

Abstract:To analyze the structural response of oil pipe under external loads, the interaction between oil pipe and its surrounding soil was simulated based on ABAQUS software, and the finite element models for apron oil pipe were established and verified. By applying the finite element models, the research presented the characteristics of additional stress distribution, and the structural stress and deformation of oil pipe varied with its buried depth induced by external loads including aircraft load, construction vehicle load and vibratory roller load respectively. The results indicate the additional stress distribution appears to be parabola curve in the range from the pipe top to the 60°side of pipe, and the additional stress values are distinct with different buried depth of pipe. The structural stress and deformation of oil pipe induced by aircraft load and construction vehicle load are far less than its allowable values, even if the buried depth approximates to its diameter, while those induced by vibratory roller load reaches strength failure criteria of pipe material, and is the most disadvantageous load type and has significant impact on the buried depth of oil pipe.

Abstract:Based on FEM software abaqus, a two-slab analysis model considering joint load transfer and interlayer contact condition is established, in which the model dimension, displacement boundary, load model, material model, joint load transfer are simplified. The Model can be used to study the mechanical behaviour of PCC pavement in process of breaking with pickaxe machine. Both deformation and tensile stress and interface shear stress of removal slab and reserved slab are calculated for typical breaking process parameter and pavement structure, the mechanism for destruction of reserved slab is also proposed.

Abstract:The Mindlin-Boussinesq uniting solution is used to calculate the additional stress, and the settlement is calculated by method of e-lgp curve. And then, the calculation results are analyzed comprehensively by comparing with existing calculation method and in-site measurement data. The research results show as follows：limitations exists in the settlement calculation of rigid piled-structure embankment under embankment loads and over-consolidated or strong structural soil by the method of existing code; the Mindlin-Boussinesq uniting solution is used to calculate the additional stress of soil between piles in rigid piled-structure embankment, the distribution along depth can accord with the actual engineering situation on; and the settlement calculated by method of e-lgp curve is relatively close to in-site measurement data, which can take the parameters of the rigid piled-structure embankment and stress history of foundation soil into consideration.

Abstract:The calculation method of track settlement which caused by subgrade differential settlement, is based on continuous elastic point supported beam model. Then the method is put forward through introducing the nonlinearity boundary conditions of cosine-type subgrade differential settlement. And the corresponding C++ calculation programming is also worked out. Finally, the calculation method is applied to the actual engineering in western extended section of Shanghai metro line 2 of shield tunnel construction, which underpass Shanghai-kunming railway. The comparative analysis between the computation result and field measurement data is conducted. And it can be concluded that the calculation result can meet the actual measurement well. The calculation value of track settling tank width is as same as the measured value basically, and the calculated subsidence amplitude of track settling tank is slightly smaller than the measured value, but the difference is less than 1 mm (approximately 4% of track settlement value).

Abstract:Abstract: On the basis of analyzing urban rail transit line operational safety，the line operational safety evaluation index system of urban rail transit is established, the meanings and calculation methods of indexes are studied and the line operating safety grade of urban rail transit is delimited. The line operational safety indexes of urban rail transit is evaluated with the method of analytic hierarchy process and entropy method combination weights, which accords with system integrity. Beijing metro line 4 is evaluated as an example to verify the rationality and reliability of this method. And it provides theoretical basis for operational safety decision-making and safety control measures of urban rail transit.

Abstract:To acurately predict the temperature fields inside a lithium-ion battery is key technology for the enhancement of battery thermal managment and the improvement of battery performances. In this paper，the dimensional analysis method is uded to derive similarity criterions and the similarity coefficients of battery interior temperature fields, based on the governing partial differential equations describing the three dimensional transient temperature field. To validate the similarity criterions and the similarity coefficients, three dimensional finite element models of battery temperature field are established, on the assumption that the battery has single-layer structure and multi-layers structure. The simulation results show that the similarity criterions and the similarity coefficients are certified correct, and they can be used for battery temperaure fields simulation and analysis.

Abstract:Conditional moment closure (CMC) model was coupled with the computer fluid dynamics (CFD) software to establish the combustion model of diesel spray in active thermo-atmosphere, the effect of ambient pressure on auto-ignition critical temperature was analyzed, meanwhile the combustion characteristics of diesel spray crossing the critical temperature range were studied. The results show that as the ambient pressure increases, the critical temperature remains around 1048K, in simulation conditions, when the co-flow temperature gets close to 1048K, 2K's co-flow temperature changes can greatly influence the flame temperature and the distribution of active components such as OH, H, HO2 etc.

Abstract:The basic principle and general scheme of disc cutters layout of shield machines were summarized, and a method of solution for general double spirals coefficients were proposed according to the optimal cutter distance and adjacent cutter phase-difference. Consequently, a different layout pattern in double spirals was provided and discussed in detail with the Shiziyang shield tunneling engineering as the case of application. Moreover, the sequence and efficiency of rock-breaking when the cutter head rotating normally and reversely were analyzed. Analysis of the statistical data of the Shiziyang tunnel construction shows that there exists a significant local wearing at the crossing of two spirals. The shield cutter layout in reverse cross double spirals pattern can raise the rock-broken efficiency when the cutter head rotating reversely, but the cutters will be worn out quickly and unevenly.

Abstract:Elevation change analysis was conducted on the ICESat (Ice, cloud, and land elevation satellite) altimetry data collected around the Amery ice shelf (AIS) from 2003 to 2009 with a repeat-track method. The average cross-track separation between the repeat-tracks at AIS was 100m, and the general slope was 0.3%. An existing digital elevation model was used to correct for effects caused by the surface slope across the repeat-track pairs. The average elevation changes were achieved in the entire study area and also within several layers of elevations in the study area. The results show that coastal areas with lower elevations tended to have significant elevation changes, varying from -40 cm to +40 cm, while interior areas with higher elevations tended to change at a low level in the range of ±10 cm.

Abstract:Considering the limitations of regular classification model using Sparse Representation (SR), this paper proposes an innovative model named Random Matrix-Nonnegative Sparse Representation (RM-NSR) to improve the classification results of hyperspectral imagery. The RM-NSR model introduces a random matrix inspired by random projection to improve the Restricted Isometry Property (RIP) condition of measurement matrix in the regular SR model. The new model also considers the non-negativity of reconstructed sparse coefficient vectors. Based on Urban and PaviaU hyperspectral datasets, three different schemes in the RM-NSR model are utilized to recovery the sparse efficient and the classification results are compared with that of the regular SR model. Experimental results show that the RM-NSR model obviously outperforms the regular SR model in the average classification accuracies (ACAs). Furthermore, the relationships between projected dimension of random matrix and the ACAs show that a greater projected dimension guarantees the improvement of ACAs by the RM-NSR model.