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To widen the application scenarios of polyurethane concrete materials, a new type of polyurethane concrete material for steel bridge deck pavement in seasonally frozen areas was developed, and it was applied to the deck pavement engineering of steel bridges with orthotropic slabs. In this paper, we studied the properties of new polyurethane concrete through the tests of compressive strength, flexural tensile strength, and bond strength with steel plates of polyurethane concrete at different temperatures from −40 °C to 60 °C, totaling 11 temperature levels. We analyzed the elastic modulus, peak strain, and stress–strain relationship curve at the standard temperature. Then, we also conducted SEM test and IR test for the internal destruction form of polyurethane concrete, and analyzed the mechanism of its strength formation. The results show that with increasing temperature, the linear elastic range of polyurethane concrete material is shortened, the elastic modulus, compressive strength, and flexural tensile strength of the material all show a downward trend, and the peak strain and ultimate strain increase significantly. The failure state of the material is gradually transformed from brittle fracture at low temperature to plastic failure at high temperature, and the ductility of the material is significantly improved. Comparing with ones at the standard temperature, the compressive strength at 60 °C is 49.62 MPa downward by 45% and the bending tensile strength of the prism test at 60 °C is 12.34 MPa downward by 51%. Although the stress performance decreases significantly with the change of temperature, it can still meet the strength requirements of the bridge deck pavement for the pavement material. At present, the relevant research is mainly focused on the mechanical properties of new concrete under the influence of high temperature, but research on the mechanical properties of new concrete along with the temperature change is relatively limited. The proposed flexural–tensile constitutive model of polyurethane concrete for steel bridge deck pavement in seasonal freezing areas under the influence of temperature is in good agreement with the experimental results, which can provide a theoretical basis for the application of polyurethane concrete in engineering.

In practice, seismic intensity is evaluated in accordance with a macroseismic-intensity scale recognized in the field of seismic engineering globally. The application of different seismic-intensity scales to evaluate the seismic damage of a specific structure due to an earthquake yields diverse results. On this basis, this study compared a few extensively used macroseismic-intensity scales. The results can be used as a reference to develop an international intensity scale. According to empirical structural-damage survey data from the Wenchuan earthquake (Mw = 8.0) that occurred on 12 May 2008 in China, the European Macroseismic Scale (EMS)-98, Medvedev, Sponheuer, and Karnik (MSK)-81, and Chinese Seismic Intensity Scale (CSIS)-08 intensity scales were utilized to evaluate the resulting damage. This study carried out a vulnerability analysis of typical structures, established vulnerability seismic-damage matrices, and mapped out vulnerability curves under different intensities. Our objective is to demonstrate that the use of multiple intensity scales can lead to very different intensity levels. The differences in the damage of typical structures under different intensity levels were obtained from an evaluation using the three aforementioned intensity scales. As a result, a calculation model of the mean damage index is proposed herein. Ultimately, this article conducted an analysis on the failure characteristics of typical structures in an earthquake and provided effective measures to improve seismic performance for future reference.

PurposeThe effects of fatigue load level and plate thickness on the fatigue performance of reinforced concrete T-beam bridges.Design/methodology/approachFatigue load tests were performed based on the fatigue damage theory of reinforced concrete, combined with finite element model analysis. The other conditions are controlled separately, and the fatigue performance of the T-beam bridge carriageway slab under different fatigue load levels and different plate thicknesses is studied.FindingsThe fatigue process of the carriageway slab of a reinforced concrete T-beam bridge is divided into three stages: fatigue damage generation, fatigue damage development and fatigue failure. Under certain other conditions, as the fatigue load level increases, the fatigue damage of the carriageway slab accelerates; as the thickness of the carriageway slab increases, the fatigue resistance of the carriageway slab improves.Research limitations/implicationsTests and simulations have been carried out, but have not been applied to actual engineering for the time being.Practical implicationsIncreasing the thickness of the carriageway slab in actual engineering is conducive to improving the fatigue performance of the bridge, and heavy-duty traffic has a greater impact on the durability of the bridge.Social implicationsIt has certain reference value for bridge design, inspection and subsequent maintenance and reinforcement.Originality/valueThe originality of this article lies in designing and carrying out static and cyclic load tests separately, while introducing material damage models based on a large number of references and combining finite element analysis to consider the impact of a specific factor on fatigue performance. The test and analysis results can provide reference for bridge design and inspection.

In this paper, we mainly studied the stress variation law of corrugated pipe culvert in permafrost regions under the influence of external load and temperature field, and formulated the corresponding experimental arrangement and observation scheme, in order to reveal the mechanical characteristics and action mechanism of corrugated metal pipe culverts.At the same time, we studied the law of the upper limit variation of permafrost foundation under corrugated pipe culvert, established the finite element model of corrugated pipe culverts, and for which we conducted mechanical analysis, frost heave analysis, and solution(thawing) settlement analysis; measured the variation of earth pressure and temperature field around pipe wall during and after filling soil.

Mechanical properties determine the use of two-component polyurethane materials. The compatibility of two components in the polyether polyol-MDI molecular system greatly influences the formation of mechanical properties in polyurethane materials. In this paper, we studied and evaluated the compatibility and mechanical properties of two-component polyurethane at multiple scales by combining molecular dynamics simulation with macroscopic experiments, which is an important guideline for synthesizing and preparing two-component polyurethanes. We evaluated the stability of the two-component polyurethane system by calculating the solubility parameter, binding energy, and diffusion coefficient at four temperatures with three isocyanate contents. The Perl scripting language obtained the mechanical properties of the MDI-polyether polyol system. The MD calculation results show that the solubility parameter of two-component polyurethane negatively correlated with temperature, and the intermolecular binding energy and MDI diffusion coefficient positively correlated with temperature. When the mass ratio of polyether polyol to isocyanate was 1:0.6, the solubility parameter difference between the two was 1.43 (J/cm3)1/2, the intermolecular binding energy was 531.68 kcal/mol, and the two-component system was more stable. A macroscopic direct tensile test was employed to assess the polyurethane elastomers’ tensile properties. Our results show that the tensile strength of polyurethane elastomers increased with the increase in isocyanate content and decrease in temperature. Furthermore, the elongation at the break decreased, and the modulus increased, which is consistent with the law of molecular simulation.

To research the seismic damage characteristics, mechanism and vulnerability of multi-storey reinforced concrete (RC) frame structures, statistics and analysis, were made on 930 RC frame structures in Dujiangyan during Wenchuan earthquake, China. Firstly, seismic damage of RC frame structure in Dujiangyan is investigated comprehensively. According to the investigation results, easily damaged locations of this kind of structural system are: infilled wall, frame column, beam-column, joints and stairs. However, a large number of RC frame structures are basically intact or slightly damaged. By using the method of numerical statistical analysis, the non-linear relationship model and the fitting curve of seismic damage investigation samples under multiple seismic damage grades are given. Considering the number of stories, multiple ages and seismic fortification influencing factors, the empirical seismic damage situation of structures under each factor is analyzed, and the non-linear regression curve is developed. The empirical seismic vulnerability matrix and continuous regression function model and curve of RC frame structure in multi-intensity region are established. A calculation model of mean seismic damage index (MSDI) is proposed, and the vulnerability matrix and regression curve based on this parameter are given in combination with the empirical seismic damage investigation data. The above research results can provide a basic reference for vulnerability analysis and intensity scale revision of RC structures.

A pile foundation in a permafrost region is in a negative-temperature environment, so concrete is affected by the negative temperature of the surrounding soil. It not only affects the formation of concrete strength but also leads to engineering quality accidents in serious cases. With the support of the two permafrost bridge projects of the national highway from Beijing to Mohe in the Greater Khingan Mountains region, a systematic remote dynamic monitoring method for ground temperature in ice-rich tundra is proposed. Based on the actual measurement of temperature at different strata depths and the comprehensive consideration of surface temperature, terrestrial heat flux and other parameters, the ground temperature profile evolution in relation to depth in Greater Khingan was established. The theoretical ground temperature profile curve is similar to the measured profile. The results show that the variation trends of ground temperatures in relation to the strata depth at different monitoring sites is similar, and all show seasonal variation: From June to November, the ground temperature at different depths tends to be constant. From December to May, the ground temperature at any depth within the range of 0 to 5.5 m follows the curve of the cosine function. Below 5.5 m, the earth temperature no longer varies with depth. The research results can be used as reference for pile foundation construction in a negative-temperature environment in ice-rich tundra.

The pile foundation in the permafrost region is in a negative temperature environment, so the concrete is affected by the negative temperature of the surrounding soil.It not only affects the formation of concrete strength, but also leads to engineering quality accidents in serious cases.Based on the actual measurement of temperature at different strata depths and the comprehensive consideration of surface temperature, terrestrial heat flux and other parameters, the law curve of temperature change along depth in Greater Khingan is established.The calculated results of the curve are consistent with the measured results of ground temperature.The results show that the variation trend of ground temperature along the strata depth at different monitoring sites is basically the same. From June to November, the ground temperature at different depths tends to be constant.From December to May, the ground temperature at any depth within the depth range of 0 to 5.5m follows the law of the cosine function.Below 5.5m, the earth temperature no longer varies with depth.The research results can be used as reference for pile foundation construction under negative temperature environment.

Acoustic emission (AE) technique was used to characterize the damage fracture process of reinforced concrete (RC) beam subjected to four-point bending. Mechanical performances and AE parameters were recorded through laboratory experiment. Gaussian filtering was adopted to interpret the AE energy and b-value obtained during testes to characterize the crack intensity and behavior. The results reveal that Gaussian filtered AE energy can realize the identification of the damage fracture process, and five stages can be classified. As for Gaussian filtered b-value, crack behavior identification effect of b-values calculated from all sensors is unsatisfactory. However, Gaussian filtered b-values obtained from amplitudes recorded through sensors at critical damage regions present clear trend and favorable identification effect.

In order to understand the seismic performance and mechanism of bottom frame seismic wall masonry structure (BFSWMS) and its vulnerability in empirical seismic damage, based on the statistical and numerical analysis of the field seismic damage observation data of 2178 Dujiangyan structures in the Wenchuan great earthquake urban of China on May 12, 2008, a non-linear function model between the seismic grade and the number of field damage samples is established, and the regression curve is given. The empirical seismic vulnerability matrices in multiple intensity regions are established, and the regression model functions of each intensity region and the vulnerability curves based on seismic damage grade and exceeding probability are obtained, respectively. A vulnerability matrix model with mean damage index (MDI) as its parameter is proposed, and the empirical vulnerability matrix is embedded in it. The vulnerability matrix based on this parameter and the regression curve of MDI in Dujiangyan city are derived. The above research results can provide the necessary practical reference for the vulnerability study of BFSWMS and the seismic code of China.

Glass with composition of 45 P2O5–53SnF2–2B2O3 (mol%) was prepared by using the one-step melt quenching method. The effect of nitrogen on tin-boron-fluorophosphate glass was investigated. Full characterizations have been carried out by the XRD and FTIR, as well as by the XPS spectroscopies. Infrared results reflected that intensity of the P = O bonds and bridging oxygen declined since the oxygen was replaced by nitrogen. XPS results suggested transformation in the bond type of glass network. The new P-N and P = N bonds was proved to exist in structure. Differential scanning calorimetry (DSC) of glass showed that the transition temperature increased with the increasing NH4H2PO4 content. Similar tendency was observed in results of thermal expansion curves (TEC), Tf =160.1℃. The weight loss of bulk glass decreased as the concentration of NH4H2PO4 increased. This work proves that the nitride tin-boron-fluorophosphate with satisfied properties has potential to be low-temperature sealing material.

Aluminium foam sandwich structures have notable advantages in energy absorption for impact protection. In this study, experiment and numerical analysis were conducted to explore the dynamic behaviours, mechanisms of deformation and damage, and energy absorption for aluminium foam sandwich structures suffering from low-velocity impact. Using a drop-hammer tester, the low-velocity impact experiments were conducted on the sandwich structure under different impact energies. The numerical calculation model was established based on ABAQUS, and the corresponding numerical analysis was performed and verified against the test results. The influences of face sheet thickness, core height and density on the performance of energy absorption for the sandwich structures were quantitatively evaluated according to energy absorption indicators. The researches indicate that the force–displacement curves exhibited three typical patterns for aluminium foam sandwich structures suffering from various low-velocity impact energies. The thickness of face sheet, core height and density had significant influence on the property of sandwich structure resistance to impact, and the combination of impact energy and energy absorption indicators play a vital role in the optimal design of sandwich structures. The present work can provide a significant reference to anti-collision design and energy absorbing evaluation for aluminium foam sandwich structures suffering from low-velocity impact.

Tinfluride-tungsten-borophosphate (SnF2-WO3-B2O3-P2O5) (SWBP) glass was prepared for sealant material by the traditional melt-quenching method. Full characterization has been carried out by FTIR and Raman spectra, as well as by the XPS spectroscopies, concluding that the non-bridging oxygen existed extensively in network, the ratio of non-bridging oxygen (NBO) to bridging oxygen (BO) was 16:1, which was considered to be sign of a stable structure. Meanwhile, the Sn(IV) to Sn(II) was 7:3, and the F Sn to F P was 7:3. The distinct structure lead to unique properties. Differential scanning calorimetry (DSC) of glass showed that the transition temperature was below 150 °C, and no crystalline points were found. Relative to chemical stability, the glass exhibited remarkable water durability and have a weight loss about 0.5 wt% in immersing measurements. In addition, proposed glass powder showed superior liquidity on metal substrate at 300 °C, which provides new ideas for the development of lower temperature and environmentally friendly of sealant materials.

The permafrost in wetland area is very sensitive to temperature change due to its special geological conditions. By observing the temperature data of the pile-soil junction of the bored concrete pile, as well as measuring the geotechnical parameters and thermophysical parameters of the soil around the pile, it statistically analyzes the significant correlation factors related to the time when the temperature of the pile-soil junction rises to the peak, including the dry density and liquid index of the frozen soil. The formula for calculating peak time is summarized and the fitting effect is compared. The results show that peak time is positively correlated with dry density and obeys cubic curve. It is negatively correlated with the liquid index and follows the growth function curve. The peak time was not significantly correlated with the buried depth of the temperature sensor, peak temperature corresponding to the peak time, natural ground temperature, original temperature of pile wall, soil thermal conductivity, volume heat capacity, natural moisture content and plasticity index of frozen soil. The influence of concrete ratio on peak time is significant, and its correction coefficient follows S-shaped curve.

The temperature field of concrete box girder under sunshine is an important factor to be considered in the design of bridge superstructure. Based on the meteorological parameters and the semi-empirical formula given by related bridge specifications, the vertical temperature gradient distribution model of prestressed concrete box girder was established using SPSS software. The amplitude of the temperature gradient model is calculated according to the theory of statistics. The index function model considering wind speed, solar radiation and temperature variation was obtained, and the method to determine the amplitude of vertical temperature gradient was summarized according to different building climate zones in China. The applicable conditions of the model are as follows: sunny and cloudless days with high radiation quantity should be selected; The selected months are generally from May to July, and June in extremely cold regions. It is verified that the calculated value fits well with the measured value by monitoring data of 3 real Bridges in different zones. The model of temperature gradient heating in warm areas was calculated. For the temperate climate regions without real bridge measured data, the recommended value of temperature gradient amplitude in this region is given after trial calculation. It explores the method of using only meteorological data without surveying and mapping, which can save a lot of manpower and material resources.

Based on the concrete test of foundation pile and the heat transfer theory between pile and soil, the heat transfer rule of pile and soil in ice-rich tundra is studied. The results show that the heat flow of foundation pile can be divided into vertical and horizontal heat flows. The vertical heat flow mainly occurs at the top of the pile and reaches the maximum value of 15.36w /m2 on 3d. It caused the pile top temperature to drop so fast that it dropped below 0°C in 3d. The value of the horizontal heat flow is 2~3 times that of the vertical heat flow. Its distribution is in descending order: the middle, the top and the bottom of the pile. The maximum temperature difference between pile center and pile wall is 6.8°C because of transverse heat flow. Local high temperature zone is formed inside the pile due to the relatively slow absorption process of thawing permafrost. Then the temperature dropped rapidly, reaching 0°C at 28d. The maximum disturbance radius in the frozen soil reaches 1.5m. Insulation layer can be added to the outside of the foundation pile during construction to obtain more uniform concrete temperature field, so as to improve the concrete strength and reduce the disturbance to the frozen soil. The construction period should be in summer.

By using ANSYS/LS-DYNA explicit dynamical analysis software, finite element models for an ice sheet and a T-frame bridge were set up individually. On the basis of the deformation compatibility condition and momentum equation, the impact force of a drift ice sheet on a bridge pier was computed. The effects of ice-breaking nose shapes on the ice impact force were investigated. The parameters studied included the nose angle of a wedge-shaped ice-breaking nose, the inclination angle of both wedge-shaped and bow-shaped ice-breaking noses, and the curvature of a bow-shaped ice-breaking nose. The research results indicated that the inclination and nose angle of a wedge-shaped ice-breaking nose and the curvature and inclination angle of a bow-shaped ice-breaking nose are important factors affecting the drift ice impact force. On the basis of the study results, design parameters for the ice-breaking nose shapes were proposed.

A detailed investigation on the fatigue performance of concrete beams strengthened with glass-fiber composite (GFC) is performed in this study. Cyclic load tests were conducted on reinforced concrete beam specimens strengthened with two layers of GFC bonded to the beams’ bottom surface using a special epoxy resin. Midspan-deflection and cracks were measured at different numbers of load cycles and varying fatigue loading levels during the tests. Investigated parameters include total midspan-deflection, residual midspan-deflection after unloading, crack width, crack length, and crack distribution at different loading stages. The fatigue performance of concrete beams strengthened with GFC was evaluated by comparing the deflections, crack sizes, and crack distributions with unstrengthened beams. The concrete beams strengthened with GFC investigated in this study showed significant improvement on fatigue performance.

Conventional asphalt bridge expansion joints used in low-temperature regions generally show cracking within the first 2 years. To improve the low-temperature performance of these joints, the commercial MEIJIA asphalt binder commonly used in bridge expansion joint construction was modified with two polymers: thermoplastic rubber and rubber. The goal is to find an optimum combination of polymers, binders, and aggregates to improve the performance of asphalt expansion joints in low-temperature regions. The polymer modified binders and mixtures were evaluated for their low-temperature properties using ductility, penetration, indirect tension, and bending tests. The study indicates that performance of these joints at low temperature can be enhanced significantly with the right combinations of polymers, binders, and aggregates. Four expansion joints made with the polymer modified asphalt mixtures were installed on two bridges in a cold region. A construction procedure was also developed to install these joints properly to minimize low-temperature cracking along the interface between the joint and bridge deck. After 7 years of service, the four joints show good performance without any visible cracking or rutting.

In this study, ice force on bridge piers during collision was investigated. A field test was performed on the Huma River Bridge in northern China and a laboratory test was performed on ice specimens to measure the compressive strength of the ice at various temperatures and strain rates. Test data was analyzed using the Universal Global Optimization (UGO) technique. Relations for ice compressive strength as functions of ice temperature and strain rate were obtained. The temperature distribution in a floating ice sheet was measured continuously for three days using Cu50 temperature sensors. The temperature distribution was observed to be nonlinear, with the lowest temperature in the middle and increased temperature toward the surfaces. A weighted-average temperature in the ice thickness was proposed to be used to determine the ice strength. Using ice strength determined by the obtained relations, the ice forces on the Huma River Bridge piers was calculated. Comparative analysis between calculated results and field tests was carried out. The computed ice force using the equation for Heilongjiang province with the ice strength determined by the obtained relations showed good agreement with the measured values.