Abstract:For the purpose of engineering application of High-Performance Lightweight Composite Bridge Decks，it was necessary to study the approximate calculation method of structural design indices. On the basis of finite element modeling，orthogonal tests were designed to obtain the key factors influencing the maximum tensile stress of UHPC，the ratio of local deflection on bridge deck，and shear stress of stud. The Latin hypercube sampling method was used to find out the internal relations between structural design indices and their key factors. Approximate calculation formulas of the maximum tensile stress of UHPC，the ratio of local deflection ，and shear stress of stud were presented，which were examined by statistical tests，judgments based engineering experiences- full-scale model tests and push-out model tests The results show that the linear correlations and regression effects of the formulas were significant，and the qualitative analysis were consistent with the general engineering experiences. The relative error between the calculated value of the three indexes and the measured value is less than 10%. They are of good applicability.

Abstract:The is paper employed the stage critical strength-considered branch-bound method to explore the major failure mode of a cable-stayed bridge,and investigated the variations of major failure mode and system reliability in the cases of cable breakage and resistance deterioration.The study indicates that,in the case of without cable breakage,the correlation among the major failure modes of the structure is high,while the correlation appears to clear grouping characteristics in the case of a sudden failure of a cable.The system reliability decreased with the resistance deterioration of the cable.Moreover,the remaining structural system reliability indices decreased remarkably in the case of the breakage of the outside cable,and the dominant cable that has the greatest impact on the system reliability was captured to guide the further structural design.

Abstract:The existing studies on the fatigue analysis for suspender of arch bridges have been found with limited consideration of the vehicle-bridge coupled vibration and road surface progressive deterioration，and those previous studies cannot reflect the actual fatigue property of the suspender.Based on the international general evaluation system of pavement roughness，a model of road surface progressive deterioration of each operation stage was established.A new model of fatigue analysis was then established by considering the effects of random traffic load model and road surface progressive deterioration.An arch bridge was taken as an example，and the differences of the fatigue performance analysis results for the typical suspender were analyzed and compared by the two situations with or without consideration of the conditions of the bridge deterioration and vehicle-bridge coupled vibration.Compared with the existing numerical method，the analysis results obtained by the proposed method show that the effects of vehicle-bridge couple vibration and road surface progressive deterioration on the suspender fatigue are significant，and the suspender fatigue value obtained by considering the above two factors can be improved by 15 years to 30 years.Therefore，the numerical results are significant for the maintenance of existing arch bridges.

Abstract:The static coefficients of typical bridge section under the wind-rain coupling effect were studied using the numerical simulation by CFD（Computational Fluid Dynamics）.Based on secondary development for the computational fluid dynamics software by applying source term，DPM(Discrete Phase Model) model combined with a UDF(User Defined Function) function method was used to study the wind-rain coupling effect on static coefficients of bridge.Meanwhile，Euler method was used to simulate the air phase and Lagrangian method was adopted to simulate the rain with discrete phase model.Impact load on the bridge section was obtained by the impulse theorem.The accuracy of the method was verified by comparing with the existing results in the corresponding literature.The wind-rain coupling effect on the static coefficients of typical bridge section is then studied，and the mechanism research of wind-rain coupling on typical bridge section was realized，which provides a theoretical method for the study of the wind-rain coupling load on the bridge.

Abstract:A numerical simulation using large eddy simulation and FW-H equation acoustic analogy was performed to analyze the acoustic field of 2-D circular cylinders with different diameters.The calculating results of the standard model were compared with the experimental results and the numerical results of other researchers.The far-field aeolian noise characteristics of 2-D circular cylinders with different diameters were analyzed.The Results show that the simulation results of the standard model are very close to the experiment results，indicating the rationality of the simulation.The peak frequency of sound pressure level of the far-field receiver decreases with the increase of the diameters of 2-D circular cylinders，and is close to the peak frequency calculated from the Strouhal number 0.2，which is considered to be the theoretical value.The overall sound pressure level of the far-field receiver under conditions of 2-D circular cylinders with diameters of 10~38 mm increases almost linearly with the diameter.With the increase of Reynolds number，the overall sound pressure level and a-weighted overall sound pressure level have an upward trend in the sub-critical range and a downward trend near the super-critical range.

Abstract:To study the influence of surface roughness on wind loads and wind-induced responses of super-tall building,a rigid model synchronous pressure measurement wind tunnel test of a square building was carried out by selecting two types of surface roughness—rough strip and sandpaper.After the analysis on the characteristics of the wind pressure distribution of the model,the aerodynamic force coefficients,the aerodynamic power spectra,and the wind-induced responses were subsequently analyzed.The results show that the spacing and thickness of the rough strip have a certain influence on the surface wind pressure of the high-rise building,but the influence is not obvious when the prominent coefficient is less than 0.4%;Sandpaper can obviously reduce the intermediate layers-average wind pressures on the windward side and the absolute values on the lateral side and lee side,and the fluctuating pressures,but would increase the absolute values of the mean wind pressures on the top of building (the influence rates are all less than 25%);The surface roughness has less effect on the along-wind aerodynamic power spectra,however,it would decrease the frequency a little (less than 5%),and meanwhile reduce the amplitude of the vortex shedding.The prominent objects on building surface in certain thickness range can reduce the surface wind loads and wind-induced responses.The roughened processing for building surface is generally conducive to structural wind resistance.

Abstract:Nonlinearly evolutionary process of damage due to material degradation is not considered in the seismic performance design of complex high-rise structure.Aiming at complex high-rise steel-concrete composite structure,the time-dependent characteristic of local component and whole structure induced by key parameters of concrete material was considered in this paper.Combining the time-dependent model of seismic damage with dynamic elastic-plastic time history analysis method,damage time-dependent characteristic of high-rise steel-concrete composite structure was studied.Because key parameters such as stiffness and damping not only have the “variable” character in service periods,but also have the “constant” character under seismic loads,the method regarding the key parameters as “quasi-variables” was proposed.Dynamic elastic-plastic time history analysis was used to obtain the dynamic response of the structure.Both the integral method based on interlayer displacement and the weighted combination method based on component’ damage were used to research on the time-dependent characteristic of the composite structure.The result shows that the structure in service period has significantly time-dependent characteristic.Time-dependent damage might exceed the corresponding threshold value under frequent earthquakes.The change of stiffness may lead to the change of the lateral force and the transmission capacity of earthquake action.Compareing the time-dependent damage in service period with design value without counting the time-dependent characteristics,it can be found that time-dependent characteristics of material have great influence on the accuracy of the seismic design and evaluation of the structure.

Abstract:To investigate the seismic performance of precast frame-shear wall structures comprised of cast-in-place concrete shear walls and prefabricated frame components，two 1/2 scale test specimens were fabricated and carried out under quasi-static reversed cyclic lateral loading in laboratory.One specimen named PCFW1 is a precast structure comprised of cast-in-place concrete shear walls and prefabricated frame components，and the other one named RCFW is a conventional cast-in-place concrete one，which is used as a reference specimen，all two test specimens are two bay-two story RC specimens.Some important characteristics such as failure process，failure mechanism，hysteretic response，displacement ductility，energy dissipation capacities and plastic hinge development process were studied.The test results show that the test specimen PCFW1 have similar failure mode compared with the test specimen RCFW.The lateral load-displacement hysteretic loops of both specimens are plump.The characteristic values of bearing capacity such as yield load，peak load，and ultimate load of specimen PCFW1 are larger than those of RCFW，but the difference is less than 10.0%.The displacement ductility of specimen PCFW1 is obviously less than that of RCFW；Grout-filled sleeves can transmit the longitudinal steel stress efficiently；The anchor bars in a knee connection in the top story can be replaced by bars wielded with anchor plate in precast shear wall-frame structures comprised of cast-in-place concrete shear walls and prefabricated frame components.

Abstract:Four RC shear wall specimens with a shear span ratio of 1.14 were subjected to rapid action of freeze-thaw cycles in artificial climate room，and then the quasi-static tests were carried out to study the deterioration of seismic behaviors of the shear walls under different action of freeze-thaw cycle.Six performance indicators，such as load carrying capacity，ductility，plastic rotation，strength degradation，stiffness degradation，and cumulative hysteretic energy dissipation，were used to evaluate the influence of the number of freeze-thaw cycles on the seismic behaviors of squat RC shear wall.The Results reveal that the embedded column and distributed reinforcement could restrain the growth and widening of frost heaving cracks and slow down the damage caused by freeze-thaw.With the increase of the number of freeze-thaw cycles，shear deformation is becoming more obvious in total deformation and the failure mechanism is changing from apparent flexure-shear dominated by flexural deformation to flexure-shear dominated by shear deformation gradually.The deterioration laws of seismic behaviors of the shear walls under action of freeze-thaw cycle are as fallows：with the increasing of the number of freeze-thaw cycles，the shear capacity is significantly reduced，but there is a significant increase in the ductility and plastic rotation; the degradation rate of strength is accelerated，and energy dissipation capacity is steadily deteriorated.

Abstract:To improve the convenience of grouting sleeve construction and explore its mechanical properties,a newly grouted sleeve lapping connector that two overlapped bars were placed,clinging to the wall of a hollow cylindrical standard steel pipe and anchored by high strength grout,was put forward.16 specimens varied in lap length were tested under tensile load.The failure mode,load displacement curve,ductility and hoop strain of sleeve were discussed.Based on the experimental results and plane section assumption,mechanical property analysis of grouted sleeve lapping connector were conducted.The relationship of sleeve hoop strain varying with lap length was studied.The lapping length is greatly reduced due to sleeve constraint.Because of sleeve deflection,the rigidity and ductility of the specimen are smaller than that of the corresponding steel.The tension in the middle of the lapping connector and the shear transferred through grout to sleeve are smaller than that in butting connector，so there is a lower requirement in anti-pull property of sleeve and bond property between grout and sleeve.When the sleeve length is short,slip in the interface of steel and grout increases the tension of middle steel,thus the resultant force of the sleeve and grout is pressure,on the contrary,the resultant force is tensile force.As the lap length increases,the maximum hoop compressive strain increases in the middle of the sleeve during the loading process.At ultimate load,as the lap length increases,the hoop tensile strain of the sleeve decreases.

Abstract:The dynamic mechanical performances of recycled aggregate concrete （RAC） incorporating with 1% to 2% nano-SiO2 or nano-CaCO3 were tested by Split Hopkinson Pressure Bar （SHPB）.The effects of different kind is of nanoparticles and different dosages on the mechanical performances of RAC were investigated.The results revealed that RACs with nano-SiO2 and nano-CaCO3 all zhowed higher dynamic compressive strength than the control RAC,and the nano-SiO2 was more effectire than nano-CaCO3 in enhancing the dynamic compressive strength of RAC.But RACs with high dosage of nano-SiO2 or nano-CaCO3 usually showed lower dynamic compressive strength than that of low dosage one,and the RAC incorporating with 1% nano-SiO2 achieved the highest dynamic compressive strength.Nano-CaCO3 exhibited more advantage in improving the deformation performance and energy absorption capacity of RAC.Both nano-SiO2 modified RAC and nano-CaCO3 modified RAC showed lower dynamic increase factor than control RAC.

Abstract:According to the highly nonlinear deformation characteristic of rocks caused by the change of voids （including initial and secondary voids），firstly，rocks can be regarded as composed of two parts: particle skeleton and voids.Then the relationships between macroscopic and microscopic aspects in stress and strain of rocks were developed by combining macro-analysis and micro-analysis respectively，which have revealed the deformation mechanism of voids rocks and have provided a theoretical basis for the simulation of the full deformation process of rocks.Afterwards，based on these researches，a new damage model considering the effect of voids change was established by Lemaitres hypothesis of strain equivalence，and then a statistical damage constitutive model stimulating the full deformation process for rocks was thus proposed by introducing statistical damage theory and the methods for determining its parameters was simultaneously given.This model can reflect not only the property of strain softening but also the nonlinear deformation characteristic of rocks caused by voids compression.Finally，through example analysis and comparison between the measured curves and the theoretical curves for this paper and similar models，the rationality and superiority of this model and methods have been indicated.

Abstract:In order to examine the influences of drying-wetting cycle on stability of cement-improved argillite-slate coarse-grained soil under dynamic loading，large-scale dynamic triaxial compression test on the soil at the standard curing age of 28 days was carried out.The mechanical characteristics parameters of improved soil，such as the change of dynamic elastic modulus，damping ratio and dynamic stress compressive strength with the drying-wetting cycles were studied by the tests.The influences of confining pressure on the dynamic properties under drying-wetting cycles were analyzed，and the influence mechanism of drying-wetting cycle was also discussed.The results indicate that：1) Both the maximum dynamic elastic modulus and dynamic compressive strength decay with the drying-wetting cycles until they are tending to be stable.2) The maximum damping ratio increases with the drying-wetting cycles until it reaches stable value.3) Under the drying-wetting cycles，the attenuations of the dynamic elastic modulus and dynamic compressive strength of the improved soil decrease with the increase of confining pressure，while the increment of the damping ratio decreases with the increase of confining pressure.

Abstract:For an embankment engineering，vehicle loads act on the pavement faceplate directly and then affect geocell reinforcement through the embankment fill.Considering this load transfer mechanism，and the effect of embankment fill stiffness and consolidation of soft soil，a geocell reinforced subgrade was regarded as a lower beam placed on Kelvin foundation and the pavement facelate was regarded as a upper beam placed on Winkler foundation.On the basis of the double-Euler-beam theory，a deformation control differential equation of geocell reinforcement and its solutions were proposed by taking into account the effect of the interaction among the pavement faceplate embankment fill，geocell reinforcement，and foundation soil.There is a good agreement when internal force and displacement calculated by the method in this paper are compared with internal force and displacement calculated by traditional method for elastic foundation beam.On this basis，the factors influencing the stress-deformation characteristics of the geocell reinforcement such as stiffness of geocell reinforcement，stiffness of embankment fill，coefficient of subgrade reaction force and the degree of consolidation of foundation soil,were discussed.The results show that flexural deformations of both pavement and geocell reinforcement reduce with the increment of stiffness of geocell reinforcement and the increment of coefficient of subgrade reaction force.And the deformations increase with the development of the consolidation of foundation soil.In addition，with higher embankment fill stiffness，the deformation of the pavement is smaller，while the deformation of geocell reinforcement is larger.

Abstract:The compaction of the red beds filling material with repeating“crush-scarifying”process in site has the property of self-similar characteristics,therefor the particle characteristics of resulting crushed products could be described by fractal dimension.Based on the fractal mechanism of repeating crush process,the method using laboratory test equipment to imitate the crush process in site was created,then the variation law of fractal dimension on the red beds filling material produced by“crush-scarifying”process was studied.Then,the inflence of partical characters on compaction and hydrogical properties was studied on the filling material with different fractal dimention,which were prepared with the method.The results show that for filling material within the same compaction parameters,the bigger fractal dimension the materail is,the easier it could be compacted;within the same compaction of the filler,the bigger fractal dimension,〖JP2〗the fewer soaking expansion and the lower compression performance the material is.To a certain extent,this paper reveals the rule of the red beds road construction affected by the particle characteristics.

Abstract:In order to improve the stability evaluation system of tunnel face，considering the effects of declined ground and tunneling footage，the upper bound expression of supporting force for three-dimensional shallow tunnel face was derived and the optimal upper bound solution of supporting force was obtained by further using the planning procedure.The results show that the ratio of supporting force of tunnel face to soil cohesion is linearly affected by the dimensionless parameter γD/c(γ is soil bulk density，D is tunnel section diameter，c is soil cohesion)，ratio of tunnel footage to tunnel depth，and ratio of ground overload to soil cohesion，whereas it is nonlinearly affected by the ratio of tunnel depth to tunnel section diameter，inclined ground surface angle，and internal friction angle. The internal friction angle，inclined ground surface angle，ratio of tunnel depth to tunnel section diameter，and ratio of tunneling footage to tunnel depth have a significant effect on the passive failure mode，while the dimensionless parameter γD/c and ratio of ground overload to soil cohesion have less effect on it.

Abstract:Based on the project of Shuangbei highway tunnel,the finite element analysis software was wsed to simulate the situation that there was the small-scale salt cavern during the construction period, and according to the critical distance calculated, a self-created device for simulating the salt cavern was taken, and then a model test with a geometric similarity ratio of 1∶25 was carried out to research the transformation law about the rock pressure,displacement of tunnel face,inner force of primary support when the tunnel was excavated to the position of critical distance and the inner pressure of the salt cavern increased until the tunnel face was broken.The results showed that,with the increases of inner pressure of the salt cavern, the tunnel face increased as almost direct proportion firstly, and then the ratio of increase became higher and higher and finally the tunnel face was broken; when the inner pressure of the salt cavern increased until the tunnel face was broken, the rock pressure showed a trend of increase in which the rock pressure of vault was the most effected location, followed by the spandrel and inflected arch, while the impact of other places was small.The bending moment distribution of steel arch is almost the same as the inner force of salt cavern increased.And as the inner force of salt cavern increased, the bending moment of vault and inverted arch showed a trend of increase in which the most effected location was focused on the vault and inverted arch while other location was less effected; what’s more, with the increases of the inner force of salt cavern, the axial force of steel arch all showed a trend of increase, and the most effected location was the vault, followed by the right and left haunch while the impact of inverted arch and spandrel were little; effected by the inner force of salt cavern change, the rock pressure,displacement of tunnel face,inner force of primary support all showed the ratio of change became faster and faster.

Abstract:Terrestrial laser scanning has been widely used in tunnel engineering，the extraction of tunnel cross sections is often based on tunnel centerlines，which is the most difficult part.A novel method for automated extraction of tunnel centerlines was presented in this paper.In this process，the boundary points of a tunnel are extracted from tunnel point clouds，the inliers for multiple model fitting are estimated from tunnel boundary points using RANSAC （RANdomSAmple Consensus） algorithm，the final centerlines are determined using a global optimization based on a re-sampled algorithm.The proposed method was applied in the Xieziyan tunnel in Sichuan.The results of application showed the extraction of tunnel centerlines achieved a high accuracy.The RSME of centerlines fitting was 16.5mm.Compared with total station surveying，the RMSE of the deviations was 10.3 mm.

Abstract:The strength reduction theory of the shortest path was used in the analysis of finite element strength reduction and limit equilibrium strength reduction,the cohesion and internal friction angle were assumed to be reduced by different reduction factor,and the reasonable reduction ratio of cohesion to internal friction angle was discussed in the case of double parameter strength reduction.Considering the influence of the buried depth of the tunnel and tunnel span,the existence of strength reduction of the shortest path in the limit analysis of shallow buried tunnel was proved.The results show that,in the shortest path of the strength reduction of shallow buried tunnel,with the increase of cohesion and internal friction angle reduction ratio，the reduction factor of cohesion increases gradually,the reduction factor of internal friction angle decreases gradually,the reduction path length decreases first and then increases, the reduction ratio and path length approximation follow a parabolic distribution,which proves the existence of the shortest path.In the shortest path of the strength reduction,the reduction range of the cohesion is greater than the internal friction angle,and with the increase of buried depth,the reduction range is gradually approaching.

Abstract:To examine the influence of slope angles and horizontal loading angles on the foundation proportional coefficient m in slope grounds，model tests of in-slope steel piles were designed and implemented，and the m-values under different slope angles and horizontal loading angles were then obtained.Model tests revealed that the m-value decreased nonlinearly with the increase of the slope angle α，horizontal loading angle β and lateral displacement x of piles at the ground surface.The m-value almost kept the same when the value of x was more than 10 mm.Moreover，the relationship among m-value and slope angle α and horizontal loading angle β was established.The contrastive analysis showed that the theoretical calculation result under the consideration of the slope space effect when determining the m-value was close to the test result，and the maximum error was no more than 10%.It is suggested to adopt the m-value when the value of x is 10 mm for the design of in-slope piles.

Abstract:Using the self-developed visualization test apparatus with constant slope and rainfall intensity and making six sets of slopes with different fine contents，centrifuge model tests on rainfall-induced debris flow were carried out.Through the analysis of slope failure patterns，the development of pore water pressure，moisture migration，and the influence of fine contents on the debris flow initiation process were studied.The test results indicate that there is a critical fine content（about15%）with the initiation of debris flow，the failure pattern of slopes is retrograded sliding when fine contents are blow the critical value，and the start time of debris flow with 10% fine content is the shortest.During the initiation of debris flow，the pore pressure increases to the peak before it declines like a wave and the curve of pore pressure tends to be gentle with the increase of fine contents.Fine contents influence the infiltration rate and the path of water，which affects slope failure patterns and determines whether the debris flow can start.

Abstract:In order to make the adjustment of blinds angle in double skin facades (DSF) more scientific and reasonable，the models of indoor comprehensive heat and average daylight factor were established，respectively.Based on the standardized process of the above two models，the evaluation model of the blinds angle of DSF was established by using the linear weighted method.The construction process of the angle evaluation model in Changsha under the condition of natural ventilation from 8 to 18 was introduced in detail.Through the simulation analysis，it is found that in sunny summer of Changsha，the optimum angle is 82°，and the optimum angle range of blinds is 73° to 90°.In cloudy summer of Changsha，the optimum angle is 0°，and the optimum angle range of blinds is 0° to 36°.

Abstract:Thermal insulation is an effective way to reduce the energy consumption of buildings.And it is friendly for environment because the reduction of energy consumption means less emission.In this paper，the transient heat transfer model was used to calculate the energy consumption caused by the heat transmission cross the exterior wall into room.P1-P2 economic model was used to analyze the life cycle total cost of exterior wall of residential building.The optimum thickness of the commonly used insulation materials including extruded polystyrene and expanded polystyrene was calculated with respect to East，South，West and North.The life cycle savings and payback periods were analyzed.The equivalent coal was calculated according to electricity consumption which is generated by the coal-fired power.Then the emission of CO2 and SO2 was estimated.The reduction potential of emissions was calculated when optimum insulation thickness was applied in comparison to un-insulated situation.Taking Changsha for example，the results show that the optimum insulation thickness is between 0.08 and 0.13m.The maximum life cycle saving varies from 116.26 to 133.45 yuan/m2.The payback period ranges from 3.1 to 3.5 years.The economic performance of expanded polystyrene is better than that of extruded polystyrene according to the economic indexes.The emission of CO2 can be reduced by 17.4~19.51 kg/m2 year，and the emission of SO2 can be reduced by 0.036~0.04 kg/m2year.The emissions can be reduced by 74.5~78.6%.

Abstract:In order to study the changes of human sweating under simulated weightlessness，the -6° Head-Down Bed Rest (HDBR) experiment usually employed in the researches of Space Medicine and the traditional experiment of human thermal comfort were carried out.During the experiment，micro current of skin，which was presumed as an indicator of human sweating，was measured on 6 male subjects under different air temperatures and relative humidity.The results showed that higher air temperature was required under lower air humidity for sweating after HDBR，and the sweat rate was found to be lower than that before HDBR.In addition，the sweat rate，indicated by skin micro current，increased with the air temperatures under neutral air humidity，but it was significantly less than that before HDBR.Furthermore，the sweat rate of the subjects after HDBR was found to increase rapidly when the air temperature was higher than 29℃ under high air humidity (80%)，and its value was approaching that before HDBR.Moreover，attenuated sensitivity of sweating was observed among the subjects during HDBR，and the sweat rate at the forehead，thorax and back was more significant than those at the lower body and forearm.The results suggest that the human sweating under simulated weightlessness is different from that under terrestrial condition，which can provide evidences for the improvements of the thermal environment during the manned spaceflight.

Abstract:As a complementary research on human thermal adaptation in air conditioning environment,this study aimed to explore human physiological thermal responses in real air conditioning environment and discuss their effects on air conditioning closing behaviors.For this,one office room,equipped with one split air conditioner,was selected to provide real air conditioning environment,and 12 students volunteered to be subjects.20 field surveys about human thermal responses to air conditioning environment when subjects just leave a non-air-conditioned environment,to simulate the intermittent running of air conditioners in real conditions,were conducted in this office room.During each survey,skin temperatures of the main body parts were measured; and human thermal sensations were recorded.Additionally,the indoor temperature and relative humidity were measured.The results showed the significant variations of foot skin temperatures and their great effects on human thermal sensations when human limbs and neck were almost exposed in air conditioning environment.In response to this,human thermal sensations presented the“step-down”trends from the votes of“thermal neutrality”to the votes of“cool”or“cold”,demonstrating the great impacts of foot skin temperatures on human thermal sensation votes.Moreover,foot skin temperatures were also found to have statistical effects on human thermal acceptance level in air conditioning environment and their actions to turn off air conditioners,which eventually resulted from human exposure environments and their thermal history.The lower the indoor temperature in air conditioning environment,the more likely subjects to turn off air conditioner.By comparison,the correlations of human thermal sensation votes and their actions to turn off air conditioners with skin temperatures of the other body parts as neck,chest,hand,forearm and thigh,as well as heart rate and blood pressure have not reached statistical significance.