Abstract:

Abstract:The exact solutions of displacement and inner force for clamped rectangular thick plate were deduced with twodimension finite integral transform method. With the employment of Mindlin theory for solving the control equation of elastic rectangular thick plate, twodimension finite integral transform was carried out for control equation without selecting displacement equation. And the high order partial differential equations were transformed to linear equations, and then the exact solutions can be obtained with integral inverted transform. The expression of displacement and inner force for clamped rectangular thick plate were deduced only with finite integral transform method and a case study was made for validation. And it was shown that the results from finite integral transform method for displacement and inner force are accurate.

Abstract:Outofplane instability is usually one of the failures for planar tubular truss without outofplane braces under ultimate load. The mixed model of beam and shell elements, with the characteristics of high solving precision and less elements, can undertake overall stability analysis as well as the joints mechanic property when solving the issue of outofplane stability. Based on the principle of mixed finite element, nodes constraint equations at the interface between beam elements and shell elements were derived. And advices on the element division and solving method were proposed in order to avoid numerical difficulty in solving the mixed finite element equations. With the numerical solution and experimental test, it was found that the outofplane instability process can be expressed accurately with less timeconsuming by the proposed method and the proposed solution. 

Abstract:Experiments and analysis were carried out for the axial compression performance of reinforcement concretefilled tubular steel(CFTS). The deformation capacity and ultimate load capacity were investigated with the analysis of loadbearing behavior, deformation capacity and failure modes of the reinforcement CFT short columns. And the influence of reinforcement on the deformation and ultimate load capacity were analysed as well. Finally, the calculation method for axial bearing capacity of reinforcement CFT short column was discussed and a simplified calculation formula was proposed. It was indicated that the columns’ failure modes were changed and their ultimate load capacity and deformation performance were improved by reinforcement.

Abstract:Based on strengthened construction technology of lateral tensioning and anchoring carbonfibre reinforced plastic (CFRP) sheet with waveshapedgear, theoretic analysis is made for the losses by material relaxation of CFRP sheet and strengthened member , the losses by temperature changing and the losses by action between screw bolt in waveshapedteeth grip and strengthened member. And prestress loss tests of CFRP after lateral tension are employed for eight members in two types of experiments (four for steel beam pedestal and four for concrete Tbeams strengthening test). Based on test and analysis, a design value of total prestress loss is proposed for CFRP sheet lateral tensioned and anchored by waveshapedgear.

Abstract:In order to consider the effect of shearing deformation and rotating inertia, an approximate method, which is based on modal perturbation method, is proposed for the free vibration analysis of nonuniform Timoshenko cantilever beams. With the eigenvalues and eigenvectors of uniform Euler beams, a set of partial differential characteristic equations of nonuniform Timoshenko beams is transformed into a set of algebraic equations for solutions of nonuniform Timoshenko beams. The method can solve the dynamic characteristics of beams with complicated crosssection, whether the crosssection variation is continuous or discontinuous. At the end, two types of beams, namely (a) discontinuous variation of thickness and (b) continuous and linear variation, are analyzed and shown that the method is simple, practicable and owns good precision.

Abstract:An incremental virtual work equation of threedimensional(3D) beamcolumn element is proposed based on the UL method. The geometric nonlinear tangent stiffness matrix for 3D beamcolumn element is deduced with the consideration of warping, shear deformation and effects of moment spatial rotation. Material nonlinearity is addressed by introducing plastic hinges at the element ends. And the Orbison sectional strength is modified in order to consider the effects of torsion moment and warping. The elasticplastic tangent stiffness matrix is acquired as the element ends are in plastic phase based on the flow theory. With a case studied, it is shown that the model can be used to predict accurately the ultimate bearing capacity and instability mode of 3Dspace frames by only one or two elements, and address the effects of warping and shear deformations effectively.

Abstract:With the actual threedimension element, the nonlinear finite element analytic models were established for boltweld joints between square concretefilled tubular (CFT) column and reduced beam section with inner separates, considering geometric large deformation, materials nonlinear and contact nonlinear. Compared with finite element model and experimental model, it was in good agreement in principle. And the characteristics of loaddisplacement(PΔ) curves, the stresses distribution of beam, the dissipating energy ability and destruction form were made with numerical analysis for bearing behavior of boltweld joints between square CFT column and reduced beam section . It was shown that the initial stiffness of joint with reduced beam section was close to that of nonreduced beam section joint. The bearing capacities of joints with reduced beam section were a little bit lower than those of nonreduced beam section joint. The plastic hinge in the joint with reduced beam section moved to the reduced beam region. The studied joints displayed a better ductility, energy dissipation and good seismic behavior.

Abstract:Based on highfrequency force balance technique in a boundary layer wind tunnel, the root mean square (RMS) coefficients of generalized force and the analytical model of the generalized force spectra of the first mode of typical lattice towers in alongwind direction were proposed. And the generalized force spectra were deduced from deriving the method of the first mode and generalized force spectra of higher modes by mode shape corrections of generalized force spectra. The top RMS acceleration responses in aeroelastic model of three typical lattice towers were evaluated by using the generalized force spectra. And compared with experimental data of wind tunnel, the influence of mode shape corrections and the contributions of higher modes and aerodynamic damping on windinduced dynamic responses were analyzed and several conclusions were drawn.

Abstract:Diagonally reinforced coupling beams were proved to have good seismic behaviors by six low frequency cyclic loading experiments with different length to height ratios varying in 1.0, 1.5, 2.0 and 2.5. Based on mechanism analysis of diagonally reinforced coupling beams with the conditions of L/h(length to height ratio)≤1.5 and1.5<L/h≤2.5, a statically indeterminate strut and tie model was proposed to simulate behaviors of diagonally reinforced coupling beams with L/h≤1.5. And 16 formula, such as geometric equation, deformation compatibility equation, physical equation and equilibrium equation were established. Compared with the experiment results, it was found that the model was appropriate for the behavior simulation of diagonally reinforced coupling beams with L/h≤1.5 .

Abstract:Soil core is commonly used in seepage flow test of centrifuge test, in which soil samples do not scale with the same rate as the model so that the fluidflow doesn’t follow the similarity criterion of hydrodynamic. Based on the similarity criterion of hydrodynamic and centrifuge test, it was proposed to achieve good similarity with adjustment of particle diameters and hydro material parameters. As it was difficult to adjust particle diameters and hydro material parameters, and based on the characteristics of distinct element method (DEM), particle flow code (PFC) was adapted to simulate seepage deformation in centrifuge test. It was indicated that the seepage flow field of the model was in good consistent with that of soil core which approved by theory analysis and experimental test. And it was shown that PFC can be practicably used in studying centrifuge test and provide reference to use PFC in centrifuge test involved seepage flow.

Abstract:There are two kinds of definitions for safety factors based on strength parameters of c tan(Definition 1) and geotechnical parameters of a, k(Definition 2) in limit equilibrium analysis with dual safety factors. The influence of different definitions on the calculation of slope safety factors is analyzed with strength dual reduction finite element method(FEM). It is shown that the safety factors are different in two kinds of definitions while the reduction rates of strength parameters(c tan) and geotechnical parameters(a, k) are in same proportion. The different DP yield criteria are related to the parameters of a and k. If circumcircle DP yield criterion is adapted, the safety factors with Definition 1 are approximate to the ones with Definition 2 on all kinds of soil slope. And if DP yield criteria of the plane strain matching and criteria of homalographic circle are adapted, the safety factors are slightly lower with Definition 2 than those with Definition 1 for clay slope and much lower for landslide zone or slip with rough broken stone

Abstract:Slope safety stability is the bottleneck problem for the development of mountainous highway, especially high class highway in China, which results from greatness slopes along highway in mountainous area, complex geological environment and short forming age. The important degree arrangement of various indexes was carried out based on simple dependent function. And weighting system of indexes was modified with analytic hierarchy process and expert reliability. With indexes and weighting system, matter element extension model for highcutting slope along highway in mountainous area was proposed by matterelement extension method. A case study was undertaken for K88+680 highcutting slopes along WushanWuxi road in Chongqing city based on the model. It was indicated that the safety grade is Ⅲ and the slope is instable.

Abstract:The modal parameters are the key indexes for the damnification diagnosis and state evaluation. But for the complexities of the structure and soil interaction effect mechanism of cantilever retaining wall system, there is still no appropriate ways to simulate the modal parameters effectively at the moment. To solve the existing problem, practical modal parameters of structure system were obtained by field impulse hammering modal test. Compared them with the modal parameters of structure system ignoring the soil influence, it was concluded that the soil influence can not be ignored. And with the consideration of soil influence, calculation methods of additional stiffness and mass were analysed and modal analysis with the finite element method was undertaken for the retaining wall as well. It was approved that the calculating method for soil influence and impulse hammering modal test is feasible with good agreement with data from field test. Finally, the main disabled modes of the retaining wall, the modal parameters characteristics under damage state and health diagnosis methods were studies and a fast, simple, lossless and effective modal analysis evaluation method was proposed for the health diagnosis of cantilever retaining wall.

Abstract:The fatigue life of cementstabilized macadam specimen beams was analyzed through coupling fracture and failure mechanics. The fracture toughness of specimen beams was calculated by finite element method(FEM). And the damage evolution equation controlled by tension stress was given, in which coefficients were backcalculated based on the fracture toughness control index using partial fatigue tests data. The life prediction precision of this equation was verified using residual fatigue tests data. It was shown that FEM is effective to calculate the fracture toughness of specimen beams. And the damage evolution equation based on the fracture toughness control index had better life prediction ability comparing with the SN equation. The proposed method can provide a calculation model to predict the service life of practical road structure.

Abstract:Frost heave has caused serious distresses to railway roadbeds in seasonal, especially deep seasonal, frozen regions. Therefore, frost heave prevention is the basic principle of roadbed design in seasonal frozen regions for many years. Frost heave has caused serious distresses to railway roadbeds in seasonal, especially deep seasonal, frozen regions. Therefore, frost heave prevention is the basic principle of roadbed design in seasonal frozen regions. The coupled heatfluid transport equation and twodimensional finite element method were employed to simulate the maximum frozen depth in the coming 50 years under the roadbed with XPS insulation board in the conditions of different depth, width, thickness and construction season for studying the insulation effect. Based on numerical simulation, appropriate depth, width and construction season were proposed for insulation design and the relationship between the thickness of insulation board and the height of roadbed was analysed as well.

Abstract:The joints of steel and concrete (JSC) is the key substructure to composite bridge, the method of condition monitoring and safety assessment were carried out for JSC with perfobond shear connectors (PBL) and local prestressed tendon in largespan bridge. According to the damage mechanism of JSC, new monitoring parameters were proposed. The sensor location layout and the assessment thresholds of PBL were addressed with the consideration of the disadvantage influences of environment, load and concrete creep to local prestressed loss assessment and validated by the static load experiment. Compared the experimental results with field monitoring data, it was found that the new monitoring parameters and new assessment method were feasible and can be used as reference to the same type connectors in largespan bridges.

Abstract:Decisionmaking for urban development strategy is a fundamental step for urban master planning. A comprehensive assessment model for urban development decisionmaking has been tested with spatial information Tupu methodology. Taking Wusheng County as an example, an adaptive scheme for urban spatial expanding was proposed with spatially overlaying multiple influential factors. The urban development space has been split into sixteen parts by two buffer circles and eight spatial quadrants. Quantitative characteristics of land use suitability in every part were addressed and analysed with information Tupu by radar map. It is found that the appropriate development axial for shortterm is northeastsouthwest while inappropriate for northwestsoutheast. And for longterm development, the appropriate ones are east, south and north while unfavorable for southwest and northwest. Spatial information Tupu is a new mode for analyzing urban development, which is more explainable and simpler. Spatial information Tupu has the ability to integrate different kinds of information and expresses them in a visually and quantitatively way so as to better decisionmaking.

Abstract:River health assessment is an essential and effective approach to river control. Historical understandings on river health especially on urban rivers are analyzed. The characteristics of mountainous urban rivers on hydrology, morphology, runoff, pollution, ecological services and anthropogenic impacts are analyzed based on a branch of the Yangtze River in Chongqing City. The watersheds including the river, its landscape and human actions are thought to be a suitable study unit, and mountainous urban river health should be of the following four meanings: internal ecological integrity, elasticity and recoverability of the river system itself, security of spatial landscape pattern of watershed, harmoniousness between the river system and urban people, and the sustainability over time of the abovementioned attributes. An indicator system was proposed for the assessment of mountainous urban river health. Analysis of spatial landscape pattern assisted with GIS tools should be emphasized as an indispensable part. 

Abstract:Comparative experiments of indoor thermal environment were undertaken, with night ventilation, in lightweight buildings with Phase Change Material (PCM) and without PCM. And the lightweight building fabric with PCM is made of selfmaking compound organic PCM and attached with EPS. Analysing the influence of PCM dosage, phase change temperature and PCM wall structure on the PCM wall performance of heat storage and release and indoor thermal environment, it was shown that the thermal inertia of enclosure could be advanced with PCM and indoor thermal comfort could be improved as well. With the night ventilation, the heat accumulated in daytime could be released outdoor. And the maximum indoor temperature decreased 11 ℃ in PCM building compared with that in common building, which met the third grade requirement from spatial and indoor environmental parametric requirements for camping (GJB 4306-2002) and held remarkable energy efficient potential. With regard to the influencing factors, dosage and phase change temperature were the key factors. And with different phase change temperatures, the temperature difference could be increased from 3 ℃ to 11 ℃ when PCM dosage doubles. Optimization design of Phase change temperature and dosage could improve the PCM performance effectively.

Abstract:Based on the disadvantages of existing building environmental analysis methods, a generic model of exergy analysis on environmental impact of building life cycle is introduced, taking into consideration of previous models and focusing on natural environment as well as building life cycle. And three environmental impacts were analyzed, namely energy consumption, resource consumption and pollutant discharge respectively. The generic model of exergy assessment on environmental impact of building life cycle thus was formulated and building environmental sustainability was evaluated through exergy footprint of building environmental impacts. With a residential building in Chongqing for case study, it was found that environmental impacts in building operational stage accounts for 88% of building life cycle and in the breakdown, environmental impacts from energy consumption and related emission were the fundamental parts with the share of 75% and 24% respectively. And for sustainability analysis, about 169 m2 earth areas with global average productivity was required to support the building’s life cycle of one m2 floor area.

Abstract:With respect to three vents located on both sides of the fire source in an asymmetrical arrangement, series of CFD simulations and reducedscale experimental tests are carried out. And further analysis is undertaken for several parameters, such as airflow distribution, flue gas temperature and smoke horizontal diffusion distance etc, with different combinations of the longitudinal velocity and exhaust rate. It is found that horizontal diffusion distance of smoke is confined in three vents bordering the fire source and optimization design with minimal exhaust rate is further proposed. With multiple CFD simulations, series of dimensionless correlations are recommended for further tunnel fire safety design with some parameters, such as heat release rate, tunnel inclination and optimized parameters with slope variation.

Abstract:The mix proportion design method of recycled concrete by close packing method of mechanically interlocked skeleton was studied, aiming at the various qualities of materials, surface properties and compact degree of recycled concrete aggregates (RCA) from different kinds. The proportion tests of four different kinds of RCA as the aggregate were carried out with the amount determination of RCA and cementing materials by close packing degree of RCA, and mortaraggregate ratio respectively. It was found that the amount of cementing materials determinated by mortaraggregate ratio was more appropriate than that by richmortar coefficient. In the testing condition, the preferable mortaraggregate ratio of C40 recycled concrete was near 0.49. And the slumps of the concretes and the 28 d compressive strengths reached at 155 mm and 52 MPa, respectively.

Abstract:The influences of the monocyclic aromatic high range water reducers on cement hydration were evaluated from four factors, such as hydration heat, hydration products, pore structure, microstructures of cement pastes. With measurement of hydration heat by the TAM Ai, it was found that monocyclic aromatic high range water reducer may delay early hydration and significantly decreased early hydration heat. And the monocyclic aromatic high range water reducers tended to increase porosity and pore volume of cement pastes with MRI analysis, while pore size distribution did not change remarkably. With analysis of XRD、TGDTA and SEM, it was shown that the monocyclic aromatic high range water reducers could restrain the production of Ca(OH)2 and Hydrated Calcium Silicates in the hydration process without affecting the end products, and refine the hydration products, such as Ca(OH)2, CSH gel and ettringite crystals.

Abstract:The theory and method of asphalt fireretardant surface modified with silane coupling agent is introduced and the optimum silane dosage is determined. The structure and performance of asphalt fireretardant before and after the surface modification is characterized through infrared spectrum and thermo gravimetric analysis. Dispersion effect of asphalt fireretardant before and after the surface modification is studied and the influence of surface modification on the hydrophilicity and lipophilicity of asphalt fireretardant is analysed contrastively. It is shown that obvious physical and chemical action occur between silane coupling agent and asphalt fireretardant, which reduce the surface polarity of asphalt fire retardant with the optimum dosage of 0.95% for the asphalt fire retardant. And Surface modification strengthens the thermal stability, dispersibility and lipophilicity of asphalt fireretardant so as to improve compatibility of asphalt and asphalt fireretardant.

Abstract:The long term shrinking strain (1~90 d) of ordinary cement mortar and styrenebutadiene rubber (SBR) latex modified cement mortar were tested by micrometer calipers, and the microimage and microstructure of mortar aged at 28 d was analyzed by pore size distribution method, density method and scanning electron microscope(SEM) image. The hydration heat of SBR latex modified neat cement mortar was measured. It was shown that the long term shrinking performance of mortars was improved when the content of SBR latex was above 3%, especially before the age of 28 d. The long term shrinking strains of mortars reduced as the increase of SBR latex content. The improving mechanisms of SBR latex on the shrinking of mortar were as follows: 1) The hydration heat reduced before 72 h, with which it reduced the thermal expansion crack of mortar. 2) The water around the SBR grain was lost during the processing of hydration, and polymer films were formed, with which it played the role of “microfiber” and restrict the shrinking of mortar. 3).As the incorporation of SBR latex, the mean pore diameter, mode pore diameter, median pore diameter of mortar aged at 28 d decreased. And the quantity of harmful and multiharmful porosity reduced with the increase of quantity of harmless porosity. Therefore it was indicated that the microstructures of mortars were improved by the content of SBR latex. 4) The total porosity of mortars declined slightly as the incorporation of SBR latex, and the proportion of closed porosity to the total pore remarkable increased, which played the role of maintaining internal water of mortar.