Abstract:With the increase of bridge main span，the slenderness ratio of the cables is getting larger and the fre? quency is getting lower and lower. Several new types of wind-induced vibrations，including wind-induced vibration of the hangers of suspension bridges，high-order vortex-induced vibration of stay cables，and galloping vibration of bridge cables attached with lighting lamps，were observed on real bridges. Due to these new challenge，the mecha? nisms and the corresponding countermeasures were carefully studied by using field observations，wind tunnel tests and theoretical analyses. The results show that the mechanism of the wind-induced vibration of the hangers of sus? pension bridges is complex and the effective measures on stay cables of cable-stayed bridges are not suitable for miti? gating the wind-induced vibration of the hangers. It seems that rigid spacers are an effective measure to reduce the relative vibration between the cables of the hanger. Large amplitude of vortex-induced vibration of stay cables is ob? served on several long-span cable-stayed bridges，which increase the difficulty of vibration control. It appears that installing two dampers at the end of the cable is an effective way to simultaneously reduce both the high-order vortexinduced vibration and the low-order rain-wind-induced vibration of stay cables. Galloping vibration can be easily evoked by installing lighting lamps on stay cables. This kind of cable vibration can be effectively mitigated by in? creasing structural damping and changing the aerodynamic configuration of the lamps.

Abstract:Multimode damping of a stay cable attached with a negative stiffness device（NSD）and a linear hys? teretic damper was studied. The frequency equation of a cable under transverse control forces at two locations is used for damping analyses by considering arbitrary NSD and damper locations. The effects of NSD and damper locations， damper parameters and negative stiffness values on multimode damping of stay cable are examined. It can be found that the multimode cable damping values can be significantly enhanced comparing with the single linear hysteretic damper. The closer the installation locations，the higher the damping level. Furthermore，multimode damping effect of the combinations is verified by using a long stay cable installed with a viscous shear damper on the Sutong Bridge， together with an inertial damper. The feasibility of the NSD is carefully discussed. The results show that the NSD is more helpful to enhance the multimode damping comparing with the inertial damper.

Abstract:Under the condition that the aerodynamic shape of the bridge and the incoming wind field are deter? mined，the Sc number is one of the key factors affecting the vortex-induced response of long-span bridges. In order to conduct a refinement study on the effect of Sc number on vertical vortex-induced vibration（VVIV）of long-span bridges，firstly a permanent magnet plate eddy current damper was developed，and it was utilized to provide linear and adjustable viscous damping for the spring-suspended sectional model system. Then wind tunnel test for a section model of a steel-concrete composite girder bridge with wind fairings was conducted under three different wind attack angles of +3°，0°and -3°，respectively，and several different Sc number. Based on the experiments，the variation of VVIV displacement with the wind velocity for different nominal damping ratio was obtained，the maximum displace? ment of the VVIV versus Sc number relationship was analyzed by curve fitting，and the higher-order modal vortexinduced vibration response of the bridge was predicted. It is found that the lock-in wind speed region as well as the maximum amplitude decrease with the increase of Sc number under all the three wind attack angles，though their varying tendencies are significantly different. The maximum amplitudes for different Sc numbers can be well pre? dicted by curve fitting of the results of wind tunnel tests for at least three different Sc numbers. On the assumption of the same modal damping ratio，the vortex-induced vibration amplitudes of all vertical bending modes of long-span suspension bridges are almost the same. As a result，the vortex-induced vibration amplitudes of higher-order modes are more difficult to meet the specification limits. The research results provide a novel method for refinement predic? tion of VVIV response of long-span bridges.

Abstract:Vibration characteristics of cable models with friction damper are studied experimentally. Firstly，the mechanical properties of the friction damper model made of copper and steel were tested. The relationship between torque and friction force of the damper bolt was obtained. Secondly，the experimental study on the free vibration char? acteristics of the friction damp-cable model was carried out. The logarithmic decay rate was obtained from the free vi? bration decay of displacement. The relationship between the logarithmic decay rate and vibration amplitude was ana? lyzed and compared with theoretical results. The free vibration acceleration time history was analyzed by the Fast Fourier Transform and Wavelet transform to derive the change of frequency spectrum with time. Finally，forced vibra? tion tests of the friction damper-cable system were carried out. The relationship between cable amplitude and excita? tion frequency was obtained by sweep-frequency technique. The mitigation effects of friction damper on cable resonance amplitude were investigated. The test results show that the friction damper can effectively reduce the reso? nance amplitude of forced vibration under small or large amplitude excitation. Friction damper was more efficient for the mitigation of amplitude excitation.

Abstract:In order to investigate the control effects on a cable structure based on blowing through uniformly dis? tributed porous surfaces，we conducted a series of wind tunnel tests. The measurements of wake flow fields of the cable structure under the uncontrolled and controlled cases with Reynolds number Re 1.0×104 were achieved by a PIV system. Instantaneous and time-averaged flow characteristics was analyzed，and proper orthogonal decomposi? tion（POD）and dynamic mode decomposition（DMD）were utilized to analyze step-down modal characteristics. The non-dimensional control parameter in the blowing control was the equivalent blowing coefficient，CQ. The experimen? tal results show that with the increase of CQ，POD modal energy distributions tend to be uniform，dimensions of co? herent structures in the global flow fields are transformed to be homogeneous and the dominance of the first two POD modes is restrained. The wake vortex shedding frequency is changed and interactions between separated shear-layers are restricted. DMD modal eigenvalues are changed and spectral distributions of mode amplitudes shifted. Further? more，the recirculation region dimension in the wake is enlarged and the turbulence kinetic energy and Reynolds shear stress are significantly weakened.

Abstract:Wind load and wind-induced vibrations of stay cables are of great concern in engineering design and wind resistance research fields. Therefore，it is necessary to explore a new type of stay cable with less aerodynamic force and excellent wind-resistant performance. To this end，a wavy stay cable was employed to study the overall aerodynamic forces，wind pressure distribution，local forces，vortex-induced vibration and dry galloping characteristics，based on a wind tunnel test. The test results indicate that，during the Reynolds number range of 1.00×105~ 3.86×105，mean drag coefficients of the wavy stay cable are generally less than those of regular stay cables，with a maximum reduction of 18% in low Reynolds numbers. The maximum mean lift coefficients are decreased by around 80%. Variation in wind pressure distribution and aerodynamic forces with the Reynolds number is almost identical to those of regular stay cables，except for weaker spanwise correlation. The vortex-induced vibration is significantly suppressed by the wavy stay cable，whose maximum amplitude is decreased by 34% and the corresponding velocity is increased by 16%. However，dry galloping is nearly the same as regular stay cables，whose maximum amplitude is decreased by 5% and sustained wind velocity range is wider.

Abstract:The time-varying characteristics of cable modal parameters and cable tensions under good weather and heavy rain are systematically analyzed based on the one-year acceleration and temperature monitoring data of five cables on a long-span cable-stayed bridge. The modal frequency and damping ratio are derived using the fast Fourier transform（FFT）and stochastic random identification（SSI）method. It is found that the cable vibrates greatly under wind and rain conditions. The low-order mode dominates the vibration，and the modal damping ratio has certain differences in the two circumstances. The tension force of each cable throughout the year，derived using the frequency method，is a non-stationary time series and has annual and daily periodic fluctuations. The correlation analysis of the cable tension and temperature shows that the correlation between the two of each cable is different， even differs on the same cable in different temperature ranges. The half-power bandwidth method is used to calculate the damping ratio of each cable for one year，the autocorrelation function and its self-power spectrum are obtained， and the edge probability density distribution function of the damping ratio is also obtained by fitting. The analysis shows that the damping ratio of each cable has the periodic components of 1 day，12 hours，and 6 hours，and its edge probability density function can be described by Burr distribution. The damping ratio of the cable is less affected by the ambient temperature but more by the vehicle load.

Abstract:In order to determine the vortex-induced vibration of the flexible hangers equipped with lighting fix? tures of an existing arch bridge，numerical simulations and wind tunnel tests were carried out. Aiming at the lighting schemes for the existing hanger and the additional hanger，the flow characteristics around typical cross-sections with different yaw angles were simulated. The variations laws of the aerodynamic coefficients and the vortex-shedding be? havior with the yaw angle are discussed. Then，the vortex-induced vibrations of hangers with different yaw angles were determined by segment wind tunnel tests. The experimental phenomena are discussed together with the results of the numerical simulations. The results show that the installation of lighting fixtures significantly changes the vortex-induced vibration performance of existing hangers. When the incoming flow is perpendicular to the bridge axis，the vortices shed from two typical cross-sections along the cable axis are different in frequency and intensity， which decreases the possibility of the vortex- induced vibration of hangers. When the yaw angle of the incoming flow is around 30°，the vortex-shedding characteristics of the two typical sections tend to be consistent，which enhances the possibility of the vortex- induced vibration of hangers. The additional hangers，which are enclosed in rectangular lighting fixtures，show more flexible characteristics and are more likely to suffer from vortex-induced vibration，so additional countermeasures need to be considered.

Abstract:Aiming at the problem of stay-cable galloping caused by lighting lamps, the galloping vibration char? acteristics and the effect of increasing structural damping on galloping-vibration were studied based on the engineer? ing background of a stay-cable installed with an elliptical lamp and a rectangular box. First, the aerodynamic coeffi? cients of stay cable were measured by the force measurement wind tunnel tests. The wind attack angle range of cable vibration was predicted by using galloping force coefficient. Then, 2- dimensional and 3-dimensional vibration tests were carried out to measure the critical wind speed of galloping. The influence of damping ratio on vibration was also studied. The test results show that the maximum drag coefficient and lift coefficient of stay cables with elliptical lamp and rectangular box are 1.8 and 1.5, respectively. The static wind load on the stay cable can be increased by 83%. The influence of local bulge point light on the aerodynamic force of stay cable is small. For two-dimensional stay cables, the most dangerous wind attack angle is 8°. The minimum galloping force coefficient is -7.9 and the minimum critical wind velocity is 21.8 m/s. For three-dimensional stay cables, the yaw angle of vibration is 40°~56° and 186°~ 196°. Both in-plane and out-of-plane vibrations occur. When ζ is 0.1%, the critical velocity is 4.7 m/s. The vibra? tion amplitude increases linearly with the increase of wind velocity. When the reduced wind velocity is 77, the dimen? sionless displacement can reach 2D（D is the diameter of stay cable）. Increasing the damping can reduce the ampli? tude of vibration at the same wind velocity. When the damping ratio is less than 0.8%, the effect of increasing damp? ing on the critical wind velocity is limited. If the damping ratio is increased to 1.0%, the galloping vibration of stay cables installed with elliptical lamps and rectangular wire boxes can be effectively suppressed.

Abstract:In order to explore the dynamic mechanical properties of the adhesive layer between UHPC and as? phalt surface for ultra-high performance lightweight composite bridge deck，the servo-hydraulic system UTM-30 was used for dynamic shear loading on the UHPC- SMA interface. On the conditions of temperature 5 ℃，15 ℃，25 ℃，35 ℃ ，45 ℃，60 ℃ and frequency 0.1 Hz，0.5 Hz，1 Hz，5 Hz，10 Hz，25 Hz，dynamic shear tests were car? ried out. The variation laws of dynamic shear modulus and phase angle were obtained for two typical adhesive materi? als，i. e. hot-melt modified epoxy 202 and high adhesion elastomer modified asphalt PG100. Based on the timetemperature equivalence principle and Sigmoidal function，the master curve of dynamic modulus and phase angle were obtained by using the least square method. The experimental results show that the dynamic modulus decreases with the increase of temperature，and increases with the increase of frequency. The phase angle increases with the in? crease of temperature，and decreases with the increase of frequency. The adhesive materials are of viscoelastic char? acteristics in dynamic response. At the same temperature and frequency，the dynamic modulus of resin 202 is signifi? cantly higher than that of asphalt PG100，its phase angle is significantly lower than that of asphalt PG100，and this phenomenon became more obvious with the increase in temperature. At 60 ℃，the dynamic modulus of resin 202 is still greater than 1.13 MPa，while the PG100 is only about 0.15 MPa. Resin 202 has better shear resistance than as? phalt PG100. The most unfavorable working conditions of the adhesive layer between UHPC and asphalt surface are high temperature and low frequency. Compared with 25 ℃ and 25 Hz（about 120 km/h），the dynamic shear modulus of resin 202 and asphalt PG100 is decreased by 34.9%，and 88.8 % respectively at 60 ℃ and 5 Hz（about 30 km/h）. For the master curve of dynamic modulus，the goodness of fit R2 of resin 202 and PG100 are 0.993 and 0.996 respec? tively. For the master curve of phase angle，the goodness of fit R2 were 0.978 and 0.989 respectively. The regression equations have a good fitting degree. The master curves can not only find out the material characteristics at high fre? quency and for a long time，but also predict the life and long-term service performances of the adhesive layer material.

Abstract:In order to study the dynamic response of a non-stationary crosswind on the train-long span cablestayed bridge coupling system，the EMD（Empirical Mode Decomposition）method is used to process the existing measured typhoon data to obtain the time-varying average wind speed of the typhoon. The average wind speed in the wind spectrum is replaced by the time-varying average wind speed，and the non-stationary crosswind fluctuating windspeed is simulated by the weighted amplitude wave superposition method. The finite element software ANSYS and the multi-body dynamics software SIMPACK are used to establish a train-track-cable-stayed bridge coupling analysis model. The non-stationary wind load includes the static wind caused by the time-varying average wind and the buffeting force caused by the non-stationary fluctuating wind. The dynamic response of the coupled system of wind-train-long-span cable-stayed bridge is calculated，and the acceleration responses of the train and cablestayed bridge under the action of stationary wind and non-stationary wind as well as the safety and comfort indexes of the train on the bridge are compared and analyzed. The results show that compared with the stationary wind，the maximum lateral and vertical acceleration of the train are increased by 12 % and 23 % under the action of nonstationary wind，respectively，and the maximum lateral and vertical acceleration of the bridge are increased by 16 % and 7 %，respectively. The wheel load reduction rate，wheel-rail lateral force and derailment coefficient of the train increase by 9 %，14 % and 4 %，respectively. The lateral Sperling index of the train increases to a certain extent， thus reducing the safety and comfort of driving on the bridge. The spectrum shows that in the low frequency region， the vertical vibration，transverse vibration of the train and the transverse vibration of the bridge are more intense un? der the action of non-stationary wind.

Abstract:To evaluate the serve status of bridge operation precisely，based on the bridge 3D point data model ob? tained at different times，the detection and tracking method of the bridge geometrical profile based on point cloud data and engineering knowledge is established. Firstly，based on the traditional ICP registration，combined with engi? neering professional knowledge，a point cloud registration algorithm that only uses relatively fixed points to partici? pate in the registration process is proposed. This algorithm is used as the main body to construct a bridge spatial de? formation identification method including the point cloud segmentation，registration，deformation identification and result verification. At last，the set of methods is applied to an engineering example to efficiently obtain the change of geometrical profile of each component of the bridge within one year，and the structural engineering knowledge is used to verify the reliability of the identification results. The results show that the proposed point cloud registration al? gorithm based on engineering knowledge can efficiently realize the precise registration of two point clouds. The change detection method of the bridge geometrical profile based on this algorithm can quickly and accurately identify the spatial deformation of bridge components（e.g. bending and torsion of girders and lateral bending of piers）in a period of time. This proposed method can provide more technical means and practical experience for the intelligent non-destructive testing of bridges.

Abstract:To identify the axle/total weight in the case of multiple vehicles，this paper proposes a twodimensional（2D）-BWIM algorithm considering the lateral position of passing vehicles. In this algorithm，only the responses of girders underneath the traveling lane are adopted to calculate the axle/total weight via using the concept of influence line. Considering the bridge′s 2D behavior，the axle weight is distributed on each girder based on the transverse distribution factors. The influence line of each girder was obtained through a calibration test with known vehicle information. In this study，an iterative method is used to identify the axle/total weight of passing vehicles in multiple vehicles present. This iterative method gives an assumption that the response of each girder is proportional to the transverse distribution factor when a single vehicle crosses the bridge. Using the assumption，the correspond? ing error is calculated based on the calibration test，and the results show that the absolute error is very small and will not affect the accuracy of axle/total weight identification later. Then，three field tests under random traffic were car? ried out to validate the proposed 2D-BWIM algorithm. For a single-vehicle passing over the bridge，the results show that the 2D-BWIM algorithm can significantly improve the accuracy of vehicle axle/total weight recognition compar? ing to the traditional Moses′ algorithm. In this case，for the 2D-BWIM algorithm，the average and variance of errors in total weight identification are 3.1% and 4.8%，respectively. While for traditional Moses′ algorithm，errors of those are 7.9% and 13.5%，respectively. For multiple vehicles presents，the average and variance of errors in axle weight identification of（Moses，2D-BWIM）algorithms are（7.34%，1.53%）and（26.33%，3.12%），respectively.

Abstract:To investigate the influence of the half-lapped joints on the bending moment capacity in the two-way directions of Cross-Laminated Timber（CLT）floors，out-of-plane bending tests in the major and the minor strength directions were performed，respectively. The test phenomena and failure modes at ultimate state in both loading di? rections were discussed，and the effects of the screw diameter，the screw spacing，and the lap length on the bending moment capacities and the strains in the mid-span cross-sections were investigated. Combined with the test phenom? ena，the deformation characteristics of the self-tapping screws in the minor direction at ultimate state were summa? rized. A calculation method for determining the bending moment capacity in the minor direction was developed，and the calculation results were compared with the test values. The results showed that the failure mode of the specimens in the major direction was the mix mode（the embedment failure，and the tensile fracture or the rolling shear of the layer），and those of the specimens in the upper lap in the minor direction were characterized by two failure modes， including the mode I（the embedment failure and the pull-through failure），and the mode II（the splits along grain in the upper lap and the pull-through failure）. The increase of the screw diameter and the decrease of the screw spac? ing had no significant influence on the bending moment capacity in the major direction. The increase of the lap length and the decrease of the screw spacing significantly improved the bending moment capacity in the minor direction. The calculation method proposed in this paper predicted the ultimate bending resisting load in the minor strength di? rection reasonably，which laid the theoretical foundation and provided the structural design reference for the promo? tion of CLT two-way slabs in the engineering application.

Abstract:To improve the calculation method of normal section bearing capacity of eccentric compression mem? ber reinforced with steel bars and Fiber Reinforced Polymer（FRP）bars，this study summed up three typical failure types，then analyzed the limit failures among each failure type，and gave relative-boundary compressive region′s height based on several tests of concrete members reinforced with steel bars and Glass Fiber Reinforced Polymer （GFRP）bars under eccentric compression. The second-order moment augmentation factor was obtained through pa? rameter analyses using ABAQUS. By considering the basic assumptions and the influence of the second-order bend? ing moment，the calculation formulas for the normal section bearing capacity of the rectangular section eccentric com? pression members were derived. By comparing the calculation results with the test results，it was proved that the cal? culation formulas proposed in this paper had good accuracy and practicability（the mean value of the ratio Nu，t/Nu，e between the experimental values and the calculated values was 0.99 and the standard deviation was 0.053），which can provide a certain theoretical guidance and design reference for the application and promotion of concrete eccen? tric compression members reinforced with FRP bars and steel bars in practical engineering.

Abstract:To study the seismic behavior of reinforced concrete（RC）frame joints affected by acid rain corro? sion，the artificial climate method was used to simulate the acid rain environment. The accelerated corrosion tests were conducted on eight RC beam-column joint specimens，and then quasi-static tests were carried out. The apparent phenomenon of the specimens corroded by acid rain was observed. The influence of corrosion cycles，axial com? pression ratio and sulfate ion concentration on the failure characteristics，hysteretic behavior，shear performance and shear capacity of the RC frame beam-column joints were analyzed. On this basis，the damage index was intro? duced，and the parameters of damage model were determined. Then，the damage evolution of the specimens during the loading process was revealed quantitatively. The results of test and analysis show that，aggregate exposure，crys? tal precipitation and eroded holes appear on the specimens due to acid rain corrosion，but the maximum shear force of corroded joint core area is still less than the threshold of the seismic shear capacity calculated by the current Chi? nese standard. With the increase of corrosion cycles and sulfate ion concentration，the bending cracks at the beam and the shear cracks at the core area appear earlier and develop rapidly，and the bearing capacity，deformation ca? pacity，energy dissipation capacity decreased gradually，while the shear proportion and damage development rate in? crease continuously. For the specimen with a larger axial compression ratio，the bearing capacity is relatively large， while the deformation capacity is poor，and the shear proportion and damage development rate increase are large.

Abstract:Determining the hot spot stress distribution along the intersecting weld of a tubular joint is the basis for calculating the peak value of hot spot stress. The study on the hot spot stress distribution along the intersecting weld of circular hollow section（CHS）T-joints is carried out and a stress distribution curve equation under out-ofplane bending moment is proposed. The finite element mesh model of CHS T-joints is established by the radial ten? sion method. The reliability of the calculation results of hot spot stress distribution at the weld toe is analyzed. The stress analysis results of three mesh models with different mesh densities are compared，which shows that the basic mesh density meets the requirements of calculation accuracy. The hot spot stress distribution along the intersection line of CHS T-joints under out-of-plane bending moment is analyzed，utilizing experimentally validated FEA mod? els，and the effects of four dimensionless geometric parameters on the shape of stress distribution curve are investigated. On this basis，the curve revision formula based on trigonometric sine function is proposed and determined. The statistical analysis compared with the UCL formula and experimental data shows that the formula proposed in this paper has higher accuracy.

Abstract:To reveal the interfacial bond behavior between square steel tube and recycled aggregate concrete （RAC）after exposure to high temperatures，a push-out test of 20 specimens after exposure to high temperatures was designed and completed by considering two parameters including the maximum temperature（T）and the replacement percentage（γ）. The failure process and morphology of the specimens were observed，the load-slip curves of the loading end and the free end were obtained，and the influence laws of test parameters on the interfacial bond behav? ior and the bond damage process were analyzed. The regression bond strength formulas and bond-slip constitutive equations of RAC-filled square steel tube（RACFSST）subjected to high temperatures were proposed. The results show that the curves shape at the loading end and the free end are similar，but the initial slip at the loading end devel? ops earlier. The shape of the load-slip curves can be divided into two types according to the maximum temperature（i. e.，T≤200 ℃ and T≥400 ℃）. The interfacial bond behavior of RACFSST is worse than CFSST（The average differ? ence of the corresponding bonding behavior is about 3.10% to 19.05%）. With the increase of T，the bond strength and the bond shear stiffness decrease at first and then increase，and the energy dissipation capacity of the interface in? creases gradually. With the increase of γ，the bond strength decreases gradually. Moreover，the bond shear stiffness and the energy dissipation capacity of the interface show the law of first increase，then decrease and then recovering slightly with the increase of γ. The initial bond damage of the interface is delayed at 600 ℃，and it tends to be earlier with the increase of γ. However，the influence of T and γ on it is not obvious at T≤400 ℃. The development speed of bond damage increases first and then decreases with the increase of T and γ.

Abstract:In order to study the influence of the aggregate silica-fume modification on the scale effect of cubic compressive strength of recycled concrete，240 recycled concrete cube specimens were conducted under the com? pression tests，taking the water-binder ratio of silica-fume paste，the recycled aggregate replacement ratio and the dimension of specimens as test parameters. The test results show that the improvement of the cubic compressive strength of recycled concrete with silica-fume modification（w/b=1.0）reaches the maximum value，while the reduc? tion in scale effect is also the most significant. The scale effect of cubic compressive strength becomes more obvious with the increase of recycled aggregate replacement ratio，and the scale effect of recycled concrete with the recycled aggregate replacement ratio of 100% is about 1.4 times that of ordinary concrete. Silica-fume modification can re? duce the scale effect of recycled concrete. When the recycled aggregate replacement ratio is 100%，the scale effect of recycled concrete with silica-fume modification is about 19.2% lower than that of recycled concrete without modifica? tion. The calculation equations of scale effect law are proposed，which can be used to analyze the cubic compressive of recycled concrete.

Abstract:To determine the pipe pressure drop characteristics in the coarse aggregate paste backfill（CPB）pro? cess. An industrial-scale loop test on the transportation characteristics of CPB was carried out. The actual rheological parameters of CPB are obtained by fitting the Buckingham equation to the loop test data，and the resistance equation was established based on the fluidity test. The response surface method（RSM-BBD）was used to analyze the trans? portation behavior of the CPB，and the effects of single-factor and multi-factor coupling on the pressure loss were ob? tained，respectively. Finally，RSM-BBD was used to optimize the pipeline transportation parameters of CPB. The re? sults show that the rheological parameters obtained by the rheological test were generally larger than those obtained by the loop test，where the differences in yield stress and plastic viscosity between the two are 10.4%~12.2% and 21%~32.8%，respectively. Response surface analysis showed that the sensitivity of a single factor on pressure loss was as follows concentration > pipe diameter > flow rate. And it was found that the interaction between factors had a significant effect，in which the interaction between mass fraction and pipe diameter played a decisive role. Taking the actual filling demand of Jinchuan as the background，the transport parameters optimized by response surface were as follows：pipe diameter 220 mm，flow rate 142.4 m3 /h，and concentration 73.2%. The research results are of great significance to the selection of the CPB system operating parameters.

Abstract:Based on the mass and momentum conservations of the continuum，this paper presents a novel coupled material point method based on the v-w formulation，which fully considers the large deformation mechanics of saturate and unsaturated structures under the interactions between the solids and the fluids. For simplicity，the gas phase is neglected in the formulation，while an additional item，i.e. degree of saturation，is incorporated in the gov? erning equations to simply study the saturated/unsaturated soils. The detailed derivation process of the governing equations，discretization process in the matrix forms and the computational cycles of CMPM is introduced. Via two benchmark examples，i.e. one-dimensional Terzaghi consolidation solution，and the Liakopoulos test，the validity of the CMPM is proven. In the end，a slope failure analysis due to the rainfall infiltration is presented，where both deep progressive and superficial slope failures are shown，further demonstrating that CMPM is a promising tool in simulat? ing hydro-mechanical problems.

Abstract:After the outbreak of COVID-19，it is worrisome that how to cope with the spread of the pandemic. Ventilation is the most important engineering control measure，ASHRAE，REHVA，SHASE and authoritative insti? tutions in China have issued many documents on how to apply HVAC system to prevent and control the spread of COVID-19，and thus this paper summarizes the contents related to the ventilation rate and air distribution. Besides， traditional total volume ventilation has the disadvantages of insufficient ventilation rate，less efficiency for shortterm exposure events at short range and high energy consumption during the pandemic. Source control based on ad? vanced air distribution has the advantages of high control efficiency，personalized adjustable，fast response and high energy saving potential，which can make up the disadvantages of the total volume ventilation scheme. Therefore，this paper systematically summarizes the technical types of source control based on advanced air distribution in coping the spread of respiratory infectious diseases. Considering that the design of ventilation system in the post-pandemic era is facing the development of“combination of normal time and pandemic period”，the advantages of applying source control in the post-pandemic era and the application schemes of source control in high-risk scenarios are dis? cussed，and the directions that need to be further explored in order to implement the design concept of“combination of normal time and pandemic period”are also discussed. This paper aims to provide a reference for the compilation of subsequent guidelines，and to bring some new ideas and enlightenments to the ventilation design for future pandemic prevention.

Abstract:Building type and built year are critical parameters to infer archetype buildings for urban building en? ergy modeling（UBEM）. Currently，it is difficult to directly obtain these data for most cities. For the building type identification，taking 21 538 building footprints（without a point of interest and community boundary information）in Changsha City as an example，this paper used the random forest algorithm to successfully identify low-rise resi? dences，apartment residences，and other types based on the geometric characteristics，with an overall accuracy of 81.7%. For the determination of built year，7 900 building footprints in the downtown area of Changsha were selected as a case study，and this paper applied the convolutional neural network algorithm to automatically extract building footprints from different historical satellite imageries，with an average precision of 80%. Then，the intersection analy? sis showed that 5 077 buildings were built before 2005，1 606 buildings were built from 2005 to 2014，and 1 217 buildings were built from 2015 to 2017. The proposed method can be easily applied to other cities，and provide data support for UBEM in the future.

Abstract:Personal comfort systems（PCS）are commonly used in residential buildings in hot summer and cold winter zone，such as infrared heaters，foot warmers，local air heaters and so on. In order to explore the characteris? tics of thermal comfort under the action of personal comfort system，Hangzhou City was selected as the object，and the questionnaire survey，field test and laboratory test. The results showed that the PCS was used more than 50% of the characteristics of thermal comfort of residents under the action of personal comfort system in winter were studied bytime from late December to early February，with peak use between 18：00 and 20：00 on a typical day. Local operating temperature around the human body can be increased by 2.7℃ on average by the PCS. Under the action of the PCS，neutral operating temperature is 15.8 ℃. From the perspective of comfort and energy saving，the operating tem? perature around the human body is suggested to controlled at 13.9 ~ 20 ℃. The body parts with significant sensation of heat feeling under the action of PCS are the head，hands and feet. The optimal skin temperature of each part was obtained as 33℃ for the head，37℃ for the front chest，35℃ for the upper arm，36℃ for the back，37℃ for the abdo? men，36℃ for the lower arm，31℃ for the hand，36℃ for the thigh，38℃ for the calf，and 35℃ for the foot. It pro? vided a basis for the quantitative demand study of the residents′ personal heating equipment to improve their thermal comfort in winter.