Hasil untuk "Bridge engineering"

Selin Şahin, Ebru Kurtulbaş, İrem Toprakçı et al.

Deep eutectic solvents (DESs) have emerged as promising green alternatives to conventional organic solvents for the extraction of bioactive compounds from natural matrices because of their tunable physicochemical properties, low toxicity, and environmental compatibility. However, most existing reviews primarily focus on application-based results, with limited mechanistic and process engineering interpretations necessary for industrial applications. This review provides a comprehensive analysis of DES-based extraction from the perspective of separation and process engineering, emphasizing the relationships between DES composition, physicochemical properties, mass-transfer behavior, and extraction performance. Key parameters, including viscosity, hydrogen bonding interactions, solvent-to-feed ratio, temperature, and water content, are critically evaluated in terms of their influence on extraction efficiency, selectivity, and scalability. Furthermore, solvent recovery, process intensification strategies, and industrial implementation challenges are discussed to bridge the gap between laboratory research and large-scale application. By integrating mechanistic insights with process-level considerations, this review provides a systematic framework for the rational design and optimization of DES-based extraction processes as sustainable and scalable-separation technologies.

Benjamin Neale, Sakdirat Kaewunruen, Dan Li et al.

This study aims to define specific transferable engineering capabilities needed for the implementation (design and practices) of circular economy (CE) within a smart city setting. We conducted a critical literature review of over 100 studies on the core values of CE and smart cities to investigate the knowledge gap in this topic and understand what specific skillset is employed by industry experts that can be harnessed on a wider scale, which can allow for the optimization of CE. There is a lack of research on the skillsets needed to implement a circular economy in any setting, and there are very few studies on circularity practices in a smart city setting. Primary data collection allows us to bridge this knowledge gap, yielding new findings that do not already exist concerning the skillset employed by experts in the field, which can positively impact the smart city settings in which a circular economy is implemented. We conducted a qualitative analysis based on expert interviews of 21 participants who have experience in the circular economy. This information will benefit the industry by informing businesses and councils about the key skillsets and capabilities to look out for when employing people to implement any aspect of circular practices in a smart city setting, with an emphasis on enhancing efficiency, achieving deliverables, and thinking systemically to address complex challenges they may face during the implementation. We also investigated the implementation of CE in smart cities to provide a well-rounded view of the different achievements and challenges faced during the process. This mainly focuses on the work of governance in smart circular cities, a factor that has many important implications and externalities in different sectors. This study describes the methodology adopted to formulate a detailed questionnaire for expert interviews with respect to the skill gap and capabilities necessary for working in the industry, the results of which aid discussions regarding the different challenges faced in CE implementation. Our findings reveal that background knowledge in engineering and sustainability is the most ‘highly critical’ hard skill according to the experts, while communication and stakeholder engagement are the essential soft skills required to ensure the success of a circular economy within smart city settings.

ZHENG Kunlong, WANG Jianyun, LINGHU Yan et al.

In order to obtain similar materials for tunnel model tests with wide matching and simple preparation methods, engineering materials such as gypsum, cement, river sand, and machine-made sand were selected, so as to meet the requirements of pre-grouting model tests for tunnel fault fracture zone that investigate the grouting effect of permeable crystalline slurry. Similar materials for surrounding rock, fracture zone, and tunnel lining were prepared through methods such as similarity constant calculation, material selection, and performance testing. The results show that the similarity constant was determined, such as Cl=50, Cγ=1, CE=50, and CQ=2 500. The experiment is conducted based on an optimized material ratio and preparation process. Similar materials with weight, compressive strength, and elastic modulus ranging from 16.65 to 17.58 kN/m3, 0.21 to 0.93 MPa, and 29.72 to 113.74 MPa are prepared by using cement, river sand, and gypsum. When mRS∶mG∶mC∶mW=1∶0.15∶0.03∶0.04, the prepared materials meet the test requirements. Selecting machine-made sand with an average particle size of approximately 0.4 mm as a similar material for the fracture zone can effectively avoid particle size effects and reasonably simulate the characteristics of loose and broken rock and soil. Similar materials with an elastic modulus of 0.38‒0.62 GPa are prepared by using gypsum, barite powder, and cement. When mG∶mBP∶mC∶mW=1∶0.09∶0.05∶1.4, the prepared materials meet the test requirements, and the self-made polyvinyl chloride (PVC) assembly mould is used for pouring. The results indicate that similar materials of surrounding rock, faults, and lining all meet the similarity relationship requirements of tunnel fault pre-grouting model tests. At the same time, by adjusting the ratio, the research results can provide more material choices for similar engineering simulations.

Xian Li, Jianzhuang Xiao, Liangyu Zhu et al.

Abstract Carbon emissions from engineering construction play a critical role in achieving urban carbon peak and neutrality goals. This study evaluates the carbon emission reduction benefits of the renovation project of Yihe Bridge on Beijing Road using a life cycle assessment (LCA) approach. The carbon emissions resulting from the renovation were compared with those of an alternative demolition and reconstruction plan. The calculation boundary for carbon emissions during the bridge construction period was defined based on the renovation project’s specifics, dividing the process into three stages: material production, material transportation, and mechanical construction. By integrating factor decomposition theory with the carbon emission factor method, a carbon emission mode was developed, allowing a comprehensive quantitative analysis for the construction period. Results indicate that total carbon emissions were 84 560.40 t, with material production contributing 94.73%, transportation 1.47%, and mechanical construction 3.80%. The carbon emission intensity of the newly expanded bridge section was 2.11 t/m2. Compared to the demolition and reconstruction, the renovation plan reduced carbon emissions by 53 643.44 t, achieving a 38.81% reduction.

Junhong Choi, Wei Chen, Hanna Liao et al.

One of the goals of synthetic biology is to enable the design of arbitrary molecular circuits with programmable inputs and outputs. Such circuits bridge the properties of electronic and natural circuits, processing information in a predictable manner within living cells. Genome editing is a potentially powerful component of synthetic molecular circuits, whether for modulating the expression of a target gene or for stably recording information to genomic DNA. However, programming molecular events such as protein-protein interactions or induced proximity as triggers for genome editing remains challenging. Here, we demonstrate a strategy termed ‘P3 editing’, which links protein-protein proximity to the formation of a functional CRISPR-Cas9 dual-component guide RNA. By engineering the crRNA:tracrRNA interaction, we demonstrate that various known protein-protein interactions, as well as the chemically induced dimerization of protein domains, can be used to activate prime editing or base editing in human cells. Additionally, we explore how P3 editing can incorporate outputs from ADAR-based RNA sensors, potentially allowing specific RNAs to induce specific genome edits within a larger circuit. Our strategy enhances the controllability of CRISPR-based genome editing, facilitating its use in synthetic molecular circuits deployed in living cells.

Michał Rybacki

Abstract: The first concepts for the construction of High-Speed Rail (HSR) in Poland date back to 1995. However, it is only in recent years that these projects have begun to take concrete shape. A key investment within the HSR program is the "Y" line, connecting Warsaw, Łodź, Poznań, and Wrocław, where trains will reach speeds of up to 320 km/h. An essential infrastructure element is the construction of the long-distance tunnel in Łodź, which will become part of a multimodal railway hub. Celebrating its 20th anniversary in 2024, TINES has played a signifi cant role in the development of modern railway track structures in Poland, particularly in slab track construction. Its innovative solutions help reduce vibrations and noise while enhancing infrastructure durability. TINES actively participates in infrastructure projects, adapting its products to meet EU and national technical standards. However, regulatory and legal challenges continue to pose a risk to the full utilization of Polish companies' potential in HSR construction. Nevertheless, the industry's commitment and growing expertise inspire optimism regarding the implementation and future development of Poland's high-speed rail system. Keywords: High-Speed Rail; Ballastless Track; Infrastructure Development

PENG Jianxin, ZHOU Pengcheng, CHENG Xiaokang et al.

In order to accurately characterize the behavior of cracks in accelerating chloride ion transport on both sides of the concrete, the concept of effective influence distance of cracks was proposed, and the crack pores were non-uniformly distributed according to the distance perpendicular to the crack surface in the modified equivalent medium model. The expression of chloride ion diffusion coefficient in crack zones of concrete was established based on the principle of flux conservation. Based on the existing experimental data, the applicability of the modified equivalent chloride ion diffusion model established in this paper was verified. Finally, the characteristics of non-uniform acceleration of chloride ion transport on both sides of concrete by cracks were discussed, and the influence of crack spacing and number on chloride ion transport was explored. It finds that the results obtained by the modified equivalent chloride ion diffusion model are in good agreement with the experimental data. The parametric studies show that with the increase in the distance perpendicular to the crack surface, the chloride ion content continues to decrease, and the chloride ion content on both sides is only 19% of that at the crack center point at the same depth of effective influence distance of cracks. The number of cracks has a certain influence on chloride ion diffusion, and the maximum increase in chloride ion content in multi-crack areas is 2% and 17% compared with that of single cracks. In addition, with the increase in the number of cracks, the diffusion capacity of chloride ions first increases rapidly and then flattens. The crack spacing has a significant effect on the multi-crack area of concrete, and with the increase in crack spacing, the overall chloride ion content in the multi-crack area decreases rapidly, and the decrease is the most obvious in the central area.

Linfa Xiao, Heng Lin, Yongxiang Wang et al.

The fatigue crack propagation behaviour of Q550E high-performance steel (HPS) is studied in this paper. Static tensile testing and fatigue crack propagation testing were carried out, and the results were compared with those of Q235. Finite element models were developed and verified against the experimental results. The impacts of the initial crack angle, crack depth ratio, stress ratio, thickness, and corrosion pitting on the fatigue crack propagation behaviour of the HPS were analysed. The results show that the fatigue life of Q550 was reduced by 18% due to the corrosion pitting, but it did not change the crack propagation path. When the stress intensity factor is higher than a certain value, the fatigue performance of Q235 is better than that of Q550E. The initial crack angle of 52.5° is the critical angle of the crack stress intensity factor. The steel tends to fracture as the crack depth ratio increases, and more attention should be paid to the effective crack length in engineering practice. An increasing stress ratio leads to a smaller stress intensity factor, and the thickness affects the stress intensity factor in the later stage. The crack stress intensity factor around the corrosion pits gradually decreases along the thickness direction, and the crack tips around the corrosion pits tend to reach the yield state initially, accelerating the fatigue fracture of the specimen and ultimately leading to a decrease in fatigue life.

Alula Kassa, Shovon Raihan, Kimitoshi Hayano et al.

In this study, a novel testing method was developed to evaluate the water absorption and retention of waste-based stabilizers using suction filtration. Suction filtration was seen to remove most of the unabsorbed and unretained water from the waste-based stabilizer without losing any waste-based stabilizer particles. Therefore, oven-drying of the wet stabilizer, which can deteriorate the stabilizer, was not necessary. In addition, a formula was introduced to estimate the residual free water in the stabilizer after suction filtration based on the particle size. This estimate was used as a correction to determine the water absorption and retention rate (Wab) of the stabilizer. Subsequently, newly developed tests were conducted on fly ash (FA), a paper sludge ash-based stabilizer (PSAS), biomass ash (BMA), and the PSAS–BMA hybrid to evaluate Wab. The results show that the PSAS exhibited the highest Wab, followed by the BMA and FA. This is attributed to the CaO content of each stabilizer, which may have initiated hydration reactions. The Wab of the PSAS–BMA hybrid was similar to that of the PSAS, which is attributed to the synergistic effects of the components of each type of waste. Finally, the strength development of the FA, PSAS, BMA, and PSAS–BMA hybrid-treated clays was investigated via cone index tests. In addition to the stabilizer addition ratio (A), the Wab of the stabilizers is suggested to be an essential indicator for predicting the strength development of clays treated with waste-based stabilizers. Parameter β, which is the product of Wab and A, governs the cone index qc of the treated clays instead of A and Wab. Thus, the modified water content, w*, which considers the absorbed and retained water as a solid instead of a liquid, was applied to the cone index test results. The results show that the qc of the treated clays is more correlated to w* than to the measured water content. An empirical relationship for predicting cone index qc using w* was also proposed.

Qinghua Xiao, Hongwei Huang, Chao Tang

Abstract The city development is closely related to the performance of the transportation network system. Bridges and roads are important parts of the transportation system, and are also inseparable components of the transportation network. However, the effect of the correlation between bridges and roads on the network system has not been studies thoroughly in the literature. Therefore, it is necessary to analyse the vulnerability of the road network when both bridges and roads are involved. In this paper, the urban road network is modeled into the form of network connection and node, based on the analysis of the related research results of road network vulnerability in the literature. Taking the urban roads at all levels as the connection and the transportation hubs (including bridges) as the nodes, the paper puts forward the corresponding measurement indexes and calculation methods, and establishes the importance and correlation analysis model of roads and bridges in the urban road network. At last, the model is applied to the road network which is 5 × 3 km2  besides Yangpu Bridge of Shanghai for verification, the importance and correlation of specific roads and bridges in the analyzed urban road network are calculated, which provides a certain basis for dealing with various emergencies leading to the decline of urban road network vulnerability. In this paper, the importance analysis of urban road network is extended to the bridge correlation analysis, so that the proposed model of the vulnerability assessment of the urban road network system is more suitable for the increasingly demand of road and bridge construction in China, and provides a certain basis for dealing with the decline of road network vulnerability caused by various emergencies.

Haiying Ma, Minghui Lai, Xuefei Shi et al.

In practice, bridge foundations and pier columns are usually constructed with cast-in-place concrete. Precast columns are currently widely used in highway bridges in China, which can save construction time and improve concrete quality. The connection between precast bridge columns and the foundation can affect how forces transfer from one to the other. This paper investigates using external sockets to form a connection between the bridge column and foundation. This method can accelerate the bridge construction time with the additional advantages of improving the orientation and creating a large erection tolerance. Two types of connections are presented and tested to investigate the behavior of the column-foundation connections and find a more suitable way to use external socket connections. The experimental results show that the column-foundation connection design satisfies the design requirements. The results also show that roughening the column surface within the external socket is more effective at connecting the column to the foundation when using an external socket compared to attaching a steel plate on the column. The experimental results are validated with a finite element analysis, resulting in a proposal regarding the column-foundation connection behavior as well as design recommendations for the external socket connection.

Amir Hossein Jafarieh, Mohammad Ali Ghannad

In this research the simultaneously effects of foundation uplift and nolinear behavior of soil were investigated. Previous studies have showed that the effects of soil-structure interaction on seismic performance can be described through introducing a limited number of nondimensional parameters. In most studies it was assumed that the foundation is bonded to the soil and the behavior of the soil is considered to be linear or equivalent linear. In study it is showed that this concept can be extended to the nonlinear soil-structure systems by introducing number of new nondimensional parameters. The main goal of this investigation is to study the variations of nonlinear displacement and ductility of nonlinear soil-structure systems. To achieve this goal, the structure was considered as an nonlinear single degree of freedom with concentrated mass which mounted on rigid foundation rested on distributed dampers and springs. Then the variations of the response of nonlinear soil-structure systems are assessed by conducting nonlinear time history analyses for a wide range of nondimensional parameters. It was shown that the total displacement of soil-structure systems increases because of nonlinear soil behavior but the ductility of the structure as a part of soil-structure system decreases in comparison to the systems with linear soil behavior. So in this study, it was proposed to decrease the safety factor for the design of foundation. Since the permanent settlement of foundation is an important index in performance of soil-structure systems therefore it was calculated for some applicable systems and it is shown that although the permanent settlement of the foundation increases by decreasing safety factor of foundation but the value of permanent settlement is acceptable for ordinary systems.

Rinaldo Paar, Ante Marendić, Ivan Jakopec et al.

The role and importance of geodesists in the planning and building of civil engineering constructions are well known. However, the importance and benefits of collected data during maintenance in exploitation have arisen in the last thirty years due primarily to the development of Global Positioning Systems (GPS) and Global Navigation Satellite System (GNSS) instruments, sensors and systems, which can receive signals from multiple GPS systems. In the last fifteen years, the development of Terrestrial Laser Scanners (TLS) and Image-Assisted Total Stations (IATS) has enabled much wider integration of these types of geodetic instruments with their sensors into monitoring systems for the displacement and deformation monitoring of structures, as well as for regular structure inspections. While GNSS sensors have certain limitations regarding their accuracy, their suitability in monitoring systems, and the need for a clean horizon, IATS do not have these limitations. The latest development of Total Stations (TS) called IATS is a theodolite that consists of a Robotic Total Station (RTS) with integrated image sensors. Today, IATS can be used for structural and geo-monitoring, i.e., for the determination of static and dynamic displacements and deformations, as well as for the determination of civil engineering structures’ natural frequencies. In this way, IATS can provide essential information about the current condition of structures. However, like all instruments and sensors, they have their advantages and disadvantages. IATS’s biggest advantage is their high level of accuracy and precision and the fact that they do not need to be set up on the structure, while their biggest disadvantage is that they are expensive. In this paper, the developed low-cost IATS prototype, which consists of an RTS Leica TPS1201 instrument and GoPro Hero5 camera, is presented. At first, the IATS prototype was tested in the laboratory where simulated dynamic displacements were determined. After the experiment, the IATS prototype was used in the field for the purpose of static and dynamic load testing of the railway bridge Kloštar, after its reconstruction according to HRN ISO NORM U.M1.046—Testing of bridges by load test. In this article, the determination of bridge dynamic displacements and results of the computation of natural frequencies using FFT from the measurement data obtained by means of IATS are presented. During the load testing of the bridge, the frequencies were also determined by accelerometers, and these data were used as a reference for the assessment of IATS accuracy and suitability for dynamic testing. From the conducted measurements, we successfully determined natural bridge frequencies as they match the results gained by accelerometers.

Marck Anthony Mora Quispe, Leonardo Todisco, Hugo Corres Peiretti

Construction of bridges span-by-span with Movable Scaffolding Systems (MSSs) is a very efficient and competitive technology. Normally used for spans between 25 and 70m, the technology has allowed reaching longer spans due to technological advances, specifically in bridge construction equipment. Thereby, the use of MSS has become widespread and well-accepted in a large number of locations across the USA and Europe. Nevertheless, despite its extended application, there is no single specific code provision that can explain, control, and give recommendations about all aspects of MSS during its design and usage. On the contrary, the information is spread over several documents. This paper aims at bridging this gap by providing an extensive review of code provisions and recommendations that can be valid for the MSS design. Applicability of these documents is discussed by analysing loads, safety factors, load combinations, limit states, as well as structural analysis and design. After this, a proposal of a design basis for MSS is presented for each aspect mentioned following provisions and recommendations of the considered codes.

behnam shirkhanghah, Houshyar Eimani kalehsar

Rapid growing of population, limitation of space, economic and social parameters are reasons that have led to the construction of tall buildings. On the other hand, due to invention of strong and lightweight materials, tall buildings had low damping ratio and long vibrational periods. For this reasons, it is necessary to investigate and analyze tall buildings under wind loads. In the present research, wind-structure interaction is performed on standard tall building CAARC using computational fluid dynamics (CFD), computational structural dynamics (CSD) and ABAQUS finite element software. The wind mean velocity profile is modelled using exponential formula in the boundary layer of atmosphere, wind turbulence is simulated using implicit large eddy simulation method (ILES), and co-simulation method is used to transfer non-uniform loads from fluid domain to structural nodes. Structural damping is determined by Rayleigh method. To validate the modelling, results are compared with reliable numerical and experimental findings. Results show that non-damped structures have responses significantly higher than damped structures. It is concluded that the distribution of the average wind pressure in high-rise buildings is influenced by the average wind speed. Therefore, in order to assurance in the design of tall structures, mechanical properties of wind and structure must be considered.

Daihai Chen, Yinxin Li, Zheng Li et al.

Taking a 62 m CFST bridge with a curved-string truss as the research object, according to its reinforcement scheme, the spatial finite element models of the bridge before and after reinforcement were established by using the general finite element software ANSYS. The natural frequencies of the bridge before and after reinforcement were calculated, and the seismic performance of the bridge was analyzed by using the response spectrum method. The results show that the frequencies of the reinforced bridges increase in varying degrees, especially the vertical and torsional frequencies. Before and after reinforcement, the maximum axial force in the upper chord of the bridge is the largest, and the shear force and bending moment are small. The maximum internal force appears at the two ends of the upper chord. This position should be regarded as the weak link of the bridge seismic resistance. Under the same conditions, the axial force of the bridge after reinforcement is reduced by about 30% compared with that before reinforcement, and the displacement of the bridge after reinforcement is reduced in varying degrees. The reinforcement measures can improve the lateral and vertical stiffness of the bridge, especially the stiffness of the deck system.

Xinping Li, Junlin Lv, Yi Luo et al.

In view of the influence of blasting excavation in the deep burial underground powerhouse on the dynamic disturbance and blasting vibration of side wall and surrounding rock, the blasting vibration test method is often used for on-site monitoring and control. Taking the blasting excavation of the high side wall of an underground powerhouse of a hydropower station as the engineering background, a long-term blasting vibration test is carried out on the site. The measuring points are arranged along the elevation direction and horizontal direction of the high side wall of the powerhouse. Through analyzing and comparing the blasting vibration velocity values extracted from a large number of on-site measured data in the elevation direction, an interesting phenomenon is found. The measured vibration velocity of the rock anchor beam in the area far away from the blasting is greater than that in the area near the blasting, and the vibration velocity after the casting of the rock anchor beam is greater than that before the casting. In order to avoid the randomness and contingency of the measured data, based on the blasting parameters, loading quantity, and rock mechanical characteristics used in the field, the elevation effect of the numerical model of the underground powerhouse is established by using the dynamic finite element software. By comparing the numerical simulation and the on-site monitoring of the elevation direction vibration velocity at the same location, it is found that the two have the same law, which verifies the reliability of the numerical calculation model. By changing the elevation and horizontal distances to select the measuring points in the numerical model, the propagation curve of the blasting vibration of the high side wall of the underground powerhouse in the elevation direction is obtained and the wave propagation phenomenon and the local elevation amplification effect of blasting vibration velocity in the side wall of the powerhouse are found. By means of changing the morphology characteristics of the rock anchor beam, a numerical calculation model of the rock anchor beam before casting is established, and the blasting vibration velocity in the elevation direction of the same measuring point as the original model is extracted. The analysis and comparison results show that the “whiplash effects” caused by the reflection superposition of the convex morphology characteristics of the rock anchor beam on the blast wave and the vibration response of the rock mass at the step part is the main factor for the elevation effect. The fluctuation phenomenon of the vibration velocity in the elevation direction is caused by the natural frequency and the main vibration mode of the high side walls, and the reflection superposition of the convex geomorphology characteristics of the rock anchor beam will aggravate this fluctuation phenomenon. Therefore, in the construction of deep underground powerhouses, attention should be paid to the blasting construction and support design of the rock anchor beam.

T. Davies-Barnard, T. Davies-Barnard, A. Ridgwell et al.

The terrestrial biosphere is thought to be a key component in the climatic variability seen in the palaeo-record. It has a direct impact on surface temperature through changes in surface albedo and evapotranspiration (so-called biogeophysical effects) and, in addition, has an important indirect effect through changes in vegetation and soil carbon storage (biogeochemical effects) and hence modulates the concentrations of greenhouse gases in the atmosphere. The biogeochemical and biogeophysical effects generally have opposite signs, meaning that the terrestrial biosphere could potentially have played only a very minor role in the dynamics of the glacial–interglacial cycles of the late Quaternary. Here we use a fully coupled dynamic atmosphere–ocean–vegetation general circulation model (GCM) to generate a set of 62 equilibrium simulations spanning the last 120 kyr. The analysis of these simulations elucidates the relative importance of the biogeophysical versus biogeochemical terrestrial biosphere interactions with climate. We find that the biogeophysical effects of vegetation account for up to an additional −0.91 °C global mean cooling, with regional cooling as large as −5 °C, but with considerable variability across the glacial–interglacial cycle. By comparison, while opposite in sign, our model estimates of the biogeochemical impacts are substantially smaller in magnitude. Offline simulations show a maximum of +0.33 °C warming due to an increase of 25 ppm above our (pre-industrial) baseline atmospheric CO₂ mixing ratio. In contrast to shorter (century) timescale projections of future terrestrial biosphere response where direct and indirect responses may at times cancel out, we find that the biogeophysical effects consistently and strongly dominate the biogeochemical effect over the inter-glacial cycle. On average across the period, the terrestrial biosphere has a −0.26 °C effect on temperature, with −0.58 °C at the Last Glacial Maximum. Depending on assumptions made about the destination of terrestrial carbon under ice sheets and where sea level has changed, the average terrestrial biosphere contribution over the last 120 kyr could be as much as −50 °C and −0.83 °C at the Last Glacial Maximum.

Lipeng An, Dejian Li, Peng Yu et al.

To systematically study the vehicle–bridge coupled dynamic response and its change rule with different parameters, a vehicle model with seven degrees of freedom was built and the total potential energy of vehicle space vibration system was deduced. Considering the stimulation of road roughness, the dynamic response equation of vehicle–bridge coupled system was established in accordance with the elastic system principle of total potential energy with stationary value and the “set-in-right-position” rule. On the basis of the self-compiled Fortran program and bridge engineering, the dynamic response of long-span continuous girder bridge under vehicle load was studied. This study also included the calculation of vehicle impact coefficient, evaluation of vibration comfort, and analysis of dynamic response parameters. Results show the impact coefficient changes with lane number and is larger than the value calculated by the “general code for design of highway bridges and culverts (China)”. The Dieckmann index of bridge vibration is also related to lane number, and the vibration comfort evaluation is good in normal conditions. The relevant conclusions from parametric analyses have practical significance to dynamic design and daily operation of long-span continuous girder bridges in expressways. Safety and comfort are expected to improve significantly with further control of the vibration of vehicle–bridge system.

Zigang Xu, Qiang Han, Junfeng Jia et al.

In order to assess the vehicle load carrying capacity of existing bridges on the national highway G103 in Beijing, the vehicle load model for the practical traffic flow conditions needs to be determined. Based on the traffic axle load data measured by the weigh-in-motion system and the methods proposed by General Code for Design of Highway Bridges and Culverts (JTG D60-2004) and Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004), the vehicle load parameters under practical traffic flow conditions are investigated. A typical 6-axle vehicle model with a 2-1-3 axial pattern is proposed by using the statistical analysis of total weight, axial weight, etc. The live load effects of Daliushu No. 2 Bridge, one highway bridge on the national highway G103, are analyzed using the proposed model and compared to the vehicle load model given in the Chinese code. The results show that there are great differences in the vehicle load parameters and the live load effects from the proposed vehicle load model increased by 20–50% compared with the model given by the code. The overweight vehicles are potential threats to the safety of existing bridges.