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Due to the simple design and convenient construction of prestressed concrete box girder bridges, it is widely used in bridge construction in China. At present, the load test of bridge is the most direct and effective method to evaluate the actual bearing capacity of the structure. However, this method has barriers including high cost, long time, and unfriendly to the damaged structure. Besides, the calculation method of the ultimate bearing capacity of damaged structures is relatively subjective and uncertain. Therefore, this study combines the full-size model test results of a newly built 30 m prestressed concrete box girder, and the mechanical properties of the test beam under three different working states (elastic, elastic-plastic, and plastic stage) are obtained. The stiffness degradation and bearing capacity change law of precast prestressed concrete box girder during failure are investigated. Two different stiffness damage reduction coefficients are defined. Combined with the structural characteristics of this kind of precast prestressed concrete box girder and the calculation formula of flexural rigidity of cracked members given by the code, the calculation formula of the actual residual bearing capacity of members is proposed based on the stiffness damage reduction coefficient. The results show that the reduction coefficients of flexural stiffness defined by the two methods have the same variation trend. The stiffness reduction effect of the box girder after damage is evident. The stiffness reduction of the box girder from the cracking damage to the ultimate bearing capacity state is about 40%, and the stiffness reduction of the two adjacent sections can be approximately linear distribution. The deviation between the residual bearing capacity calculated based on the stiffness damage reduction coefficient and the test value is less than 5%. Combined with the distribution law of the stiffness reduction coefficient along the longitudinal section of the box girder, the distribution law of the actual residual bearing capacity along the longitudinal section of the box girder after the damage occurred in the midspan section can be calculated. This calculation method changes the previous assessment method of structural technical condition from qualitative assessment to quantitative assessment, which can be the reference for evaluating the technical condition of damaged bridges and the calculation of residual bearing capacity in engineering. [ABSTRACT FROM AUTHOR]

The Wan Jiang Bridge in China was damaged by ship impact and subsequently restored. This paper presents a detailed evaluation of the residual service life (RSL) of the bridge using the reliability analysis method of the Joint Committee on Structural Safety, based on the structural load-bearing capacity (LBC) of the bridge and the design load. Data were collected from bridge design codes, field loading tests and finite-element (FE) analysis. The LBC was initially calculated and subsequently revised using specific coefficients. Using FE analysis, the bending moment on the control section of the bridge was determined under the most unfavourable loading conditions and the ultimate LBC of the bridge was checked. Subsequently, static and dynamic loading tests on the restored bridge were conducted, with the load and capacity determined for the control section based on FE analysis. The loads considered were dead load, vehicle load and crowd load. A time-dependent reliability index was developed for the restored bridge using the probability distributions of capacity and design load variables, and the RSL was determined. This case study, predicting the RSL of the bridge based on a multitude of data, should be valuable for future bridge maintenance and management. [ABSTRACT FROM AUTHOR]

In addition to common synoptic wind system, the mountainous terrain forms a local thermally driven wind system, which makes the mountain wind system have strong terrain dependence. Therefore, in order to estimate the reliable design wind speeds for structural safety, the samples for extreme wind speeds for certain return periods at mountainous areas can only come from field measurements at construction site. However, wind speeds measuring duration is usually short in real practice. This work proposes a novel method for calculating extreme wind speeds in mountainous areas by using short-term field measurement data and long-term nearby meteorological observatory data. Extreme wind speeds in mountainous area are affected by mixed climates composed by local-scale wind and large-scale synoptic wind. The local winds can be recorded at construction site with short observatory time, while the extreme wind speeds samples from synoptic wind climate from nearby meteorological station with long observatory time is extracted for data augmentation. The bridge construction site at Hengduan Mountains in southwestern China is taken as an example in this study. A 10-month dataset of field measurement wind speeds is recorded at this location. This study firstly provides a new method to extract wind speed time series of windstorms. Based on the different windstorm features, the local and synoptic winds are separated. Next, the synoptic wind speeds from nearby meteorological stations are converted and combined with local winds to derive the extreme wind speeds probability distribution function. The calculation results shows that the extreme wind speed in the short return period is controlled by the local wind system, and the long-period extreme wind speed is determined by the synoptic wind system in the mountain area. The descending slope of the synoptic wind speed exceeding probability exceeds the local wind by about 20%. If the influence of mixed climate is not considered, and the wind speed samples are not divided by category, the decline slope will be 7% lower. [ABSTRACT FROM AUTHOR]

Automated truck platooning (ATP) has gained growing attention due to its advantage in reducing fuel consumption and carbon emissions. However, it poses serious challenges to highway bridges due to the load effect of multiple closely spaced heavy-duty trucks on the bridge. In China, ATP also has great application prospects in the massive and ever-increasing highway freight market. Therefore, the load effects of ATP on bridges need to be thoroughly investigated. In this study, typical Chinese highway bridges and trucks were adopted. ATP load models were designed according to the current Chinese road traffic regulations. The load effects of ATP on highway bridges were calculated using the influence line method and evaluated based on the Chinese bridge design specifications. Results show that the load effect of ATP on bridges increases with the increase in the gross vehicle mass and the truck platooning size but decreases with the increasing inter-truck spacing and the critical wheelbase. The Grade-I (best quality standard) highway bridges are generally capable of withstanding the ATP loads, while caution should be exercised for other bridges. Strategies for preventing serious adverse impacts of ATP load on highway bridges are proposed. [ABSTRACT FROM AUTHOR]

As a type of urban life project in China, bridges need a certain capacity of trains running safely after an earthquake to ensure and guarantee transportation on railway lines, post-disaster reconstruction and relief work. Since aftershocks may occur after the main shock, the earthquake-induced irregularity and aftershock intensity are fully considered, based on the running safety index in the seismic design of bridges. However, there is a lack of research on the running safety of trains after an earthquake; it is mainly judged on experience, and lacks theoretical basis. In this paper, the established finite element model of a train bridge interaction system with symmetry was considered. The point estimation method (PEM) combined with moment expansion approximation (MEA) is used for random calculation of the Housner Intensity (HI). Furthermore, running safety indexes were analyzed and the running safety performance of a simply supported bridge with symmetry was assessed under a post-earthquake condition. Then the limit value, to ensure the traffic safety performance after an earthquake, is calculated based on stochastic analysis. The HI can be calculated with full consideration of the randomness of aftershock intensity and structural parameters. On this basis, a calculation method of the HI that considers the randomness of aftershock intensity is proposed. This study can be helpful for the performance-based design of symmetric railway structures under post-earthquake conditions. [ABSTRACT FROM AUTHOR]

With China's government facilitating railway projects, more railway bridges (RBs) are gradually built in complex and difficult mountainous areas (CDMAs). The construction activities of RB in CMDAs are facing formidable challenges in terms of the natural environment, technology, and organization management, which are hardly solved by traditional bridge design and construction techniques. Therefore, there is an urgent need for technology innovation (TI). Studies on the management of RB-TI in CMDAs are limited. As such, this study aims to offer an effective modular management approach to RB-TI in CMDAs. A system of demand and obstacle factors for RB-TI in CMDAs was identified firstly based on the literature review and the grounded theory, including seven intermediate codings and 29 initial codings. Then these factors were regarded as the system requirements for modular decomposition, to establish a "cut-to-fit" modular management approach to RB-TI in CMDAs. A case (i.e., the LD bridge project of the CZ railway) was selected to demonstrate and validate the developed approach. The results show that the proposed approach can be applied to manage RB-TI in CMDAs. The innovation of this study lies in the integration of grounded theory and modular theory and provides modular management ideas and measures for bridge engineering technology innovation. Findings from this study enrich the knowledge body of RB-TI and guide innovation subjects in the practical management of RB-TI in CMDAs. [ABSTRACT FROM AUTHOR]

To ensure the safe construction of bridge pile foundation in karst area, it is necessary to accurately detect the unfavorable geological conditions such as karst cave and soft layer before excavation. In this paper, the transient electromagnetic method is used to probe the geological conditions near the pile Y1 of an interworking main bridge in China's Hunan Province. By arranging 5 measuring lines at the pile Y1, the voltage variation laws of 21 monitoring points on each measuring line are obtained, and the resistivity variation cloud maps at the measuring line positions are inversed. The results show that the voltage signals at line 1 and line 5 are obviously abnormal, and the resistivity varies greatly within 50 m underground depth, which indicates that there may be adverse geological conditions such as karst cave and carbonaceous limestone interlayer. Further, through on-site hole digging and sampling, it is found that the slag sample in the area above 50 m of the stratum of pile Y1 is wet, and the slag sample below 50 m is dry without argillaceous interlayer, which verifies the effectiveness of transient electromagnetic detection method. Because the transient electromagnetic detection technology does not need drilling and the detection process is convenient, it may provide a new means for quickly detecting the integrity of the bearing layer of bored cast-in-place pile in bridge construction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The community structure of planktonic and benthic diatoms exhibited significant variations. • The biodiversity of planktonic and benthic diatoms showed exhibited significant variations. • The dispersal limitation dominated the assembly of planktonic and benthic diatom communities. • The dispersal limitation contributes more to the benthic diatom community assembly. Diatoms are an indispensable component of river ecosystem biodiversity and play an important role in aquatic ecosystems. The community assembly mechanism of diatoms has always been a central issue in the study of aquatic ecology. In recent years, many measures have been implemented in the Ashi River Basin (ASRB) to promote social and economic development, such as bridge construction, river bottom sand mining, agricultural irrigation, and urban expansion. However, there are few studies on the effects of these activities on the mechanism of diatom community assembly. First, we found that the α- and β-diversity of planktonic diatoms was higher in the normal season, while the α- and β-diversity of benthic diatoms was higher in the dry season, and the α- and β-diversity of both planktonic and benthic diatoms was reduced in the wet season. Second, the community structures of planktonic and benthic diatoms were significantly different in different hydrological periods, and the differences between planktonic diatoms communities were more evident than those between benthic diatom communities. Third, distance-decay analysis indicated that the distribution of the two types of diatom communities in the ASRB was influenced by both dispersal limitation and environmental selection. Finally, variance partitioning analysis revealed that dispersal limitation was the dominant driving factor for the spatial and temporal differentiation of planktonic and benthic diatoms. Our study reveals the important role of dispersal limitation in the community assembly of planktonic and benthic diatoms in rivers under different hydrological conditions. This study provides new insights for further understanding the relative importance of niche theory and neutral theory to aquatic microbial community assembly. Our research provides key information for analysing the structure of aquatic ecosystems and basic data for designing biodiversity conservation strategies in China's cold watersheds. [ABSTRACT FROM AUTHOR]

The Jinsha River rail–road double-deck arch bridge (bridge designed to 250 km/h) of the Chengdu–Guiyang high-speed railway (HSR) (designed to 350 km/h) is a complex system with a novel structure in China. The upper deck carries a four-track railway while the lower deck carries a six-lane urban expressway, with a height difference of 32 m. The bridge is located in the mountainous river reach of the city of Yibin. The 336 m main span adopts a high-pier, rigid steel frame, parallel tied-arch structure, built using cantilevers and temporary stay cables with the cable crane method. The 116 m and 120 m side-arches are reinforced concrete, simply-supported, basket-lifting tied-arches built by the mass cast in situ method. The rare layered structure gathers different arch types (top-bared, bottom-bared and half-through arches) into one bridge, which brought significant challenges to its design and construction. Other innovative solutions included flexible hangers passing through rigid hangers for the layered stiffening decks, ultra-high-performance concrete for the steel orthotropic deck road pavement and the use of boat shipments to overcome the scarce availability of flat land at the site. This paper describes some of the salient design and construction challenges of this landmark structure, the world's first double-deck HSR arch bridge. [ABSTRACT FROM AUTHOR]

Due to its structural efficiency, durability, and cost-effectiveness, ultra-high performance concrete was utilized to build the first highway overpass bridge in China. The bridge was made of prestressed ultra-high performance concrete box girders of four continuous spans of 30 m each. As the original design of such bridge was observed to be somewhat conservative, its cross-sectional dimensions, in the form of the box girder wall thicknesses were optimized in this research to lower the material cost in future bridge construction. Then, a full-scale simply supported ultra-high performance concrete box girder of 30 m span, incorporating the new box girder wall thicknesses, was fabricated and then tested under static loading to obtain research data to justify the revised design. The loading system was designed to examine the flexural behavior of the girder using two concentrated loads symmetrically located at the mid-span. Experimental results show that the optimized girder has a favorable ductile behavior and excellent flexural strength, which can meet the design requirements for serviceability and ultimate limit states. A finite element model of the tested girder was developed, using ABAQUS software, and then was verified using the experimental findings. A parametric study was then conducted to investigate the influence of key parameters on the structural response, namely, the reinforcement ratio, the number of the prestressing wires, and the web thickness. Recommendations on minimum and maximum compressive strength and tensile property of ultra-high performance concrete were proposed. Also, a simplified calculation method of prestressed ultra-high performance concrete box girder was developed based on a verified strain and stress diagrams for cross-sectional analysis. The proposed methodology can be used in future practice with confidence. [ABSTRACT FROM AUTHOR]

Prestressed concrete continuous beam-arch composite bridge with concrete-filled steel tube is a new type of bridge developed in recent years. It has the characteristics of strong spanning ability and large in-plane stiffness, but the lateral stiffness of the arch ribs for this type of bridge is relatively weak. In order to effectively improve the construction quality and structure stability, and optimize the mechanical properties, and in addition of realize the design of large span continuous beam-arch composite bridge, a comprehensive safety assessment of the Liuxi River bridge during construction and serving stages located in China was conducted in this paper. The results show that the bridge had favorable safety margin during the construction and severing stages. The outcomes of this study can provide technical support for the safety and smooth implementation of the bridge's safeguard, which has important theoretical significance and engineering application value. [ABSTRACT FROM AUTHOR]

During the construction of suspension bridges, the stress state of the pylon (tower) is improved by pushing the pylon saddle by an appropriate distance at the proper time. An analytical algorithm for the assessment of the required timing and displacements for the pylon saddle pushing at particular construction stages is proposed and verified in this study. The timing calculation is based on the assessment of current hanger tensile forces at each construction stage and the pylon stress state, while the pushing distance/displacement is derived from the conditions of elevation difference closure and the conservation of unstrained length of the main cable segments. This algorithm was successfully applied during the construction of a particular suspension bridge in China with a main span of 730 m. The results obtained strongly indicate that the bending moment in the pylon bottom is contributed by both horizontal and vertical forces of the main cable. The horizontal constituent is dominant and its share gradually increases in the bridge construction process. In a suspension bridge with side spans of various lengths, the stresses in the pylon bottom on the side with a larger side span is more likely to exceed the limit. Therefore, the respective strength criterion controls the pylon saddle-pushing schedule. The proposed analytical algorithm is quite straightforward and is recommended for wider application. [ABSTRACT FROM AUTHOR]

Summary: A carbon footprint (CF) assessment of Chinese high‐speed railways (HSRs) can help guide further development of the world's longest HSR network. In this research, a hybrid economic input‐output and life cycle assessment (EIO‐LCA) method was applied to estimate the CF of the Beijing‐Shanghai HSR line. Specific CFs were analyzed of different subsystems of the line, different stages of production, and three calculation scopes. Results showed that the annual CF of the Beijing‐Shanghai HSR is increasing, whereas the per‐passenger CF constantly declined between 2011 and 2014. Scope 1 emissions account for an average of 4% of the total annual CF, Scope 2 contribute 71%, and Scope 3 comprise 25%. Among the different stages, operation contributes the largest (71%), followed by construction (20%) and maintenance (9%). In the construction stage, the bridges have the largest CF, followed by trains, and then rails. A trade‐off exists between the increase in carbon emissions due to construction of bridges and the reduction in operation emissions affected by leveling changes in terrain. The Beijing‐Shanghai HSR line has a relatively higher per‐passenger CF than eight other HSR lines, which is largely due to China's coal‐based carbon‐intensive energy mix of electricity generation, high proportion of bridges, higher operating speed, and heavier train body. In the future, cleaner electricity supply options, more efficient raw material production, and improvement of trains are keys to reducing the CF of Chinese HSRs. [ABSTRACT FROM AUTHOR]

Long-span concrete-filled steel tubular (CFST) hybrid arch bridge is one of the optimal solutions for large-span bridge construction, where the construction process and long-term sustained loading may affect the structural performance during its life-cycle. The trussed CFST hybrid arch of the Pingnan Third Bridge in China with a main span of 575 m was taken as a benchmark case to numerically determine the life-cycle based structural performance of long-span CFST hybrid arch bridge, and the construction process and long-term service period were considered. The accuracy of the numerical method was validated with the in-situ measured records of the real bridge and a series of available laboratory tests. Thereafter, the life-cycle based working mechanism of the trussed CFST hybrid arch was investigated. Parametric investigations were also carried out to evaluate the influence of key parameters on the load-bearing capacity of the hybrid arch structure. Furthermore, the resistance of the structure was examined using GB/T 51446–2021. It is shown that the simulated results agree well with the in-situ measured and experimental data. The stress redistribution exists in the CFST chord during construction and long-term service phases. The influence of CFST chords is significant to the load-bearing capacity of hybrid arch as the core concrete plays a prominent role, while the effects of the web (brace) strength and web (brace) - to - chord diameter ratio are limited. It is recommended to use GB/T 51446–2021 for resistance prediction of the long-span CFST hybrid arch bridge. • Life-cycle based structural performance of the long-span arch bridge was clarified. • Working mechanism of the trussed CFST hybrid arch was revealed. • Key factors affecting the load-bearing capacity of the structure were identified. • Resistance verification of long-span CFST hybrid arch bridge was conducted using national standard GB/T 51446–2021. [ABSTRACT FROM AUTHOR]

Highlights • Cyclic tests were carried out based on the first rocking bridge in China. • Buckling-restrained plates were adopted to enhance its seismic performance. • Improved force-displacement model considering the compression depth was proposed. Abstract Seismic resilient structures with low structural damage and self-centering behavior after an earthquake are focus issues of current earthquake engineering. Unbonded pretensioned rocking columns offer advantages for accelerated bridge construction in seismic regions, which utilize column-uplifting mechanisms, high strength post-tensioning, and replaceable energy dissipation devices to enhance seismic performance and resilience. The experiment of three 1:3 scale unbonded, post-tensioned rocking bridge bents with different types of external replaceable energy dissipation devices subjected to quasi-static loading protocols, were carried out according to practical engineering demand in high-intensity earthquake regions. An improved analytical model was proposed for predicting the force-displacement relationship of the post-tensioned rocking bridge bent systems considering the neutral axis depth. Minimal physical damage was observed for the post-tensioned rocking bridge bent systems, which exhibit good energy dissipation and self-centering behavior. Especially, the external replaceable buckling-restrained plates dissipaters can be easily replaced if severely damaged subjected to higher than expected ground motions. The satisfactory analytical and experimental comparisons are presented as a validation of the reliability for the high-performance seismic-resistant bridge bent systems and the modelling techniques in this study. [ABSTRACT FROM AUTHOR]

Asynchronous construction is a new construction method for composite girder bridges with corrugated steel webs. This new construction technology has multiple advantages over conventional cantilever construction technology, including a simple basket structure, low steel consumption, high material utilization, short construction period and superior stability. Herein, a 1:1 full-scale corrugated steel web model test is designed based on the Fenghua River Bridge, which is the longest span composite girder bridge with corrugated steel webs in China. This test analyzes the shear stress distribution of corrugated steel webs under the most unfavorable stress conditions and the ultimate bearing capacity of single corrugated steel webs under the most unfavorable load conditions during asynchronous construction. The deformation and stress conditions are measured to identify critical stress areas during construction. Additionally, the safety of each area during construction is verified to provide guidance for asynchronous construction plans for the same type of bridge structures. • A 1:1 full-scale test of a composite bridge with corrugated steel webs during asynchronous construction was performed. • The vertical deflection difference between adjacent sections should be considered to control the linear of the main girder. • A temporary horizontal support should be added to the corrugated steel webs to prevent the lateral deformation of the web. • The corrugated steel webs have sufficient safety factor during asynchronous construction. • The flange steel plates under loading points should be reinforced To prevent buckling. [ABSTRACT FROM AUTHOR]

Abstract Ship impact is a potential hazard for bridge piers located in navigation waterways. To avoid direct contact between the ship and the pier, protective structures of different types are currently widely used in bridge designs against ship impact. As one of these protective structures, the flexible floating device has drawn much attention in recent years. The main advantage of this device lies in its low cost and its ability to float on water surface regardless of water elevation. This paper aims to evaluate the effectiveness of a flexible floating anti-collision device adopted in the Zhanjiang Bay Bridge located in Guangdong Province, China, using finite-element models. Detailed illustrations of the structural configurations are provided. In addition, finite-element models of the ship and the floating device with calibrations using experimental data are developed. The influences of several factors upon the ability of the device to turn the navigation direction of the ship, the energy-dissipation capacity of the device and the effectiveness of the device for reducing the impact force on the pier, are thoroughly evaluated using the validated finite-element models. [ABSTRACT FROM AUTHOR]

A new closure joint construction of immersed tunnel, the deployable element, was developed in Island and Tunnel Project of Hong Kong-Zhuhai-Macao Bridge. The method shortens installation time at sea, enables positive connection and waterstop under water, and makes the work reversible. In this paper, the author presents the concept and critical issues of design and construction of this method. Further, its improvements for future application were discussed. [ABSTRACT FROM AUTHOR]

The immersed tunnel of the Hong Kong-Zhuhai-Macao Bridge (HZMB) is the first of its kind constructed using semi-rigid elements and making a breakthrough in the structural theory. This paper explains the reason for applying the semi-rigid elements in an immersed tunnel and provides the design details using the example of the HZMB Tunnel. A theoretical analysis method based on the body-spring model is proposed for segmental joints of the semi-rigid elements. Potential challenges in the application of the semi-rigid elements are identified. Compared with the rigid (monolithic) elements and flexible (segmental) elements, the semi-rigid elements can improve the safety of segmental joints by increasing the flexural rigidity and joint friction. In addition, applying the semi-rigid elements can reduce the construction cost by retaining prestressed cables. Despite the advantages of the semi-rigid elements, some uncertainties arise due to the functional change of prestressed cables from a temporary structure to a permanent one. The location, number, and prestress level of the remaining prestressed cables need to be studied in accordance with the mechanical and waterproofing properties. The long-term prestress loss of prestressed cables should also be taken into consideration, especially the loss of asymmetric prestress in a marine environment. With the development of economy in costal regions, more immersed tunnels will face the similar engineering geological problems as the HZMB Tunnel. Discussing the technology of semi-rigid element has both engineering and theoretical significance to the development of immersed tunnels. [ABSTRACT FROM AUTHOR]

Lateral berms are often constructed to protect highway bridges against debris flows in mountainous regions. Currently, different solutions for lateral berm design are debated. The lack of standardization results in the improper design of lateral berms, limiting the mitigating effect. In this paper, a monitoring case of the mitigating effect of a lateral berm is introduced. The lateral berm was constructed through a bridge culvert at the alluvial fan of a debris-flow gully. In September 2008, a debris flow in this gully completely buried the lateral berm. The proposed numerical integral method was used to back analyse the flowing velocity and mud depth in berm. Results supported the speculation that abrupt decreases in mud depth and flow velocity in the lateral berm caused deposits that compressed the effective berm depth and resulted in overtopping flow. Therefore, we suggested reducing the berm width in order to increase the flow velocity in the berm. In June 2011, another debris flow with a smaller magnitude occurred in the gully, and the reconstructed lateral berm reportedly performed well to protect the bridge of Yalu highway. The case studies highlighted that berm width should be one of the main considerations in the berm design. [ABSTRACT FROM AUTHOR]

This study investigated the backwater effect of the eight bridges along the Huaihe River in China using physical model experiments. The experimental data obtained were used to derive equations to parameterise the backwater effect of a single bridge. The cumulative effect of two bridges was then analysed, using the backwater effect of a single bridge as a reference. It was found that, in order to eliminate the cumulative effect, the minimum distance between two bridges should be no less than 215 times the bridge pier width. [ABSTRACT FROM AUTHOR]

The mage trans-strait fixed links are constructed in different countries to promote regional economic and social development. This paper proposes a spatial impacts model for the trans-strait fixed links in the Pearl River Delta, China. To verify the rationality of the model, four quantitative indicators, including weighted average travel time, the economic linkage intensity, the economic linkage membership grade, and the fractal index are used to investigate the effect by construction of Humen Bridge, Hong Kong–Zhuhai–Macao Bridge and Shenzhen–Zhongshan Bridge. The results show that the Hong Kong–Zhuhai–Macao Bridge and Shenzhen–Zhongshan Bridge greatly improve the regional accessibility with a maximum decrease weighted average travel time of 1.38 h and 0.4 h. The central part of the Delta has greatest impacts. The links increase the economic linkage of cities of each side. The cities directly connected to the fixed links (Hong Kong, Shenzhen, Macao and Zhongshan) experience the highest increasing economic linkage. The regional spatial pattern evolves from unipolarity to multi-polarity and integrates a more advanced and sophisticated spatial network. The theoretical spatial impacts model for the trans-strait fixed links accords with the actual development in the Pearl River Delta. [ABSTRACT FROM AUTHOR]

• Flexural behavior of UHPC wet joint in prefabricated multi-girder bridge. • Eleven full-scale specimens were tested under bending moment. • Cracking resistance and flexural capacity of the specimens were discussed. • Key factors influencing flexural behavior of UHPC wet joint were revealed. • Configuration and flexural capacity were provided for UHPC wet joint. A new type of prefabricated multi-girder bridge with UHPC wet joint was used in an expressway bridge under construction in China, taking advantage of the excellent mechanical property of UHPC. As a kind of accelerated bridge construction (ABC) technology, the bridge decks are prefabricated in the factory with normal concrete and connected by cast in-situ UHPC wet joint. Straight overlapping of the longitudinal reinforcement was designed in this paper to simplify the complex configuration of the wet joint with annularly overlapped reinforcements in engineering practice. Eleven full-scale specimens divided into five groups were manufactured and tested to investigate the flexural behavior of the multi-girder bridge deck with UHPC wet joint. The influence of overlapping form, overlapping length and reinforcement ratio of the longitudinal reinforcement as well as the section form of the wet joint on the flexural behavior of the UHPC wet joint was revealed and discussed systematically, and compared with the integral concrete bridge deck. The crack load, location of the initial crack, nominal cracking stress, and ultimate load bearing capacity of the specimen were observed and discussed in detail. The test results indicate that the straight overlapped reinforcement is capable of providing sufficient anchorage effect between the rebar and UHPC with a minimum overlapping length of 10 times of the diameter of the reinforcement (10 d b). It is demonstrated that the adoption of UHPC is beneficial to simplify the complex overlapping of the reinforcement and minish the width of the wet joint. Increasing overlapping length of the reinforcement has marginal influence on the flexural behavior of the bridge deck in case that the minimum overlapping length is satisfied. However, increasing reinforcement ratio and using the diamond-shaped wet joint are helpful to improve the flexural behavior of the bridge deck including crack load, location of the initial crack and ultimate load bearing capacity. The ultimate bending capacity of the bridge deck with UHPC wet joint was analyzed theoretically and the theoretical analysis results agreed well with the test results and failure mode of the specimens. The present research findings are useful to provide comprehensive understanding on flexural performance and design guidance of UHPC wet joint in prefabricated multi-girder bridge. [ABSTRACT FROM AUTHOR]

The being built Hongkong-Zhuhai-Macao Bridge is about 50 km, and the major project of bridge and tunnel in the sea is 35.6 km, with a design life of 120 years and 6 years long construction period. This project has the longest mileage, largest investment and the biggest difficulty in construction in China construction history of sea-crossing bridge. In order to accelerate the progress and improve the quality, the technology of the integration of precast and aquatic installation is used in the pile caps and piers of the non -navigable bridges. Deep water pier is divided into two/three prefabrication, and prestressed rolling continuous external thread bars are settled in the pier, with a diameter of 75 mm, yield strength of 830 MPa, and tensile strength of 1 030 MPa. All the installation of steel bar and part of the tensioning of the bottom section pier are completed in the pier precasting yard. The rest of the connection, tensioning, and grouting of the prestressed steel bar are conducted in the water conservancy project site. We emphatically expounded the technical process of the installation of CB03 in pier precast yard and tensioning prestressed steel bars in Hongkong-Zhuhai-Macao Bridge project , which has certain reference value to similar construction engineering projects. [ABSTRACT FROM AUTHOR]

In China, large open-pit mines mainly adopts single shovel-truck technology. It always uses both sides of end slope for in-pit waste dump. Under certain conditions, the central bridge transport system can effectively shorten the travel distance of a truck and reduce the transportation cost. We established an inequality to optimize the reasonable service level of middle bridge under the complex geological conditions dumping considering that transportation distance with middle bridge is less than without one. Analysis of the feasibility of the central bridge transport system, when the bottom of the pit begins to enter the area of the sharp decline, rise and fault in coal seam. [ABSTRACT FROM AUTHOR]

Study of load effects on bridges with large windward sides has to consider not only passing vehicles but also wind actions. This paper concerns the method to calculate actual load effect and fatigue damage under combined actions of traffic and wind, taking one of the steel rods of Anyang Bridge as an example project. Firstly, internal force time-history of the rod was simulated based on measured data of traffic load and wind field. Then, extreme values of internal force of the rod were extrapolated using an improved method based on level crossing, and stress spectra of three fatigue-prone details on the rod were gained using the rain-flow method. Finally, the rod was checked under ultimate limit state and fatigue limit state, respectively. It was found that characteristic values of internal force of the rod under combined actions of traffic and wind increased from +5 849/-4 063 kN (considering vehicle actions alone) to +6 350/-5 466 kN and the maximum damage degree of fatigue-prone details increased from 0.61 (considering vehicle actions alone) to 0.63. These results suggest that wind load contributes a significant increase to internal force characteristic values of the rod but a small increase to fatigue damage. However, high stress amplitudes due to wind load do not allow infinite life design. The actual load level is much higher than that prescribed in the design code. Hence, wind actions should be fully considered. Lasteinwirkung und Ermüdungsschäden an Brücken unter kombinierter Belastung von Verkehr und Wind: Eine Fallstudie. Bei Untersuchungen zu Lasteinwirkungen bei Brücken mit großer Windangriffsfläche müssen neben den Verkehrseinwirkungen auch die Windeinwirkungen berücksichtigt werden. Der vorliegende Beitrag erörtert anhand eines Stahlstabes der Anyang Bridge beispielhaft ein Verfahren zur Berechnung der tatsächlichen Lasteinwirkung und Ermüdungsschäden infolge kombinierter Einwirkung von Verkehr und Wind. Zunächst wurde anhand von Messdaten zu Verkehrslast und Windfeld die zeitliche Entwicklung der Schnittkraft des Stabes simuliert. Anschließend wurden anhand der verbesserten Methode auf Basis des Last-Kollektivs (Klassengrenzen-Überschreitungen) die Extremwerte der inneren Kräfte des Stabes extrapoliert. Die Belastungsspektren dreier ermüdungsanfälliger Details des Stabes wurden anhand des Rainflow-Verfahrens ermittelt. Abschließend wurde der Stab im Grenzzustand der Tragfähigkeit bzw. im Grenzzustand der Ermüdungsfestigkeit geprüft. Es wurde festgestellt, dass die charakteristischen Werte der Schnittkraft des Stabes unter kombinierter Einwirkung von Verkehrs- und Windlast von 5 849/-4 063 kN (bei ausschließlicher Betrachtung der Verkehrslast) auf 6 350/-5 466 kN anstiegen. Der maximale Schadensgrad ermüdungsanfälliger Details stieg von 0,61 (bei ausschließlicher Betrachtung der Verkehrslast) auf 0,63. Diese Ergebnisse deuten darauf hin, dass die Windlast erheblich zum Anstieg der charakteristischen Werte der Schnittkraft des Stabes beiträgt und einen kleinen Anteil am Anstieg der Ermüdungsschäden hat. Dennoch erlauben die hohen Belastungsamplituden infolge der Windlast keine Auslegung für unbegrenzte Lebensdauer. Die tatsächliche Belastung ist deutlich höher als nach der Bemessungsnorm zulässig. Windeinwirkungen sind daher in vollem Umfang zu berücksichtigen. [ABSTRACT FROM AUTHOR]

Limit state design method based on probability theory is used in the Chinese highway bridge design codes which adopt partial factors in the design equations. In this paper, a virtual bridge dataset (VBD) including a total of 8064 RC T-beam bridges designed based on the Chinese highway bridge design codes was established. With this VBD, the influences of the different design parameters including span length, girder spacing, concrete grade, reinforcement grade, number of design lanes, and actions on the reliability of the RC T-beams were studied. A Monte-Carlo simulation combined with first order second moment method was employed to calculate the reliability indices of the bridges in the VBD. By conducting a statistical analysis on the calculated reliability indices, it is shown that the reliability indices follow a normal distribution and there is good consistency in the reliability of the bridges with different parameters. Construction cost for the bridges with spans of 16 m in the VBD was calculated, indicating that the construction cost increases along with the increase of the reliability indices. Suggestions with regard to the determination of the target reliability of the bridges in multi objects were also proposed. [ABSTRACT FROM AUTHOR]

Underwater sound generated by pile driving was recorded during the Hong Kong-Zhuhai-Macau Bridge (China) construction in 2014.The important parameters on the source level, the transmission loss, the time-frequency characteristics, and the method of the noise measurement were introduced in this paper. Signal analysis showed that the waveform of pile driving resembles a series of short pulses, composed of many different frequencies with main frequency energy distribution from 100 Hz to 2 kHz; the maximum value occurs at about 200 Hz. The best-fit shallow water sound propagation model gave a root-mean-square source level of 208.2 dB re $$1~\upmu \hbox {Pa}$$ at 1 m, a transmission spreading coefficient of 17.76, and an absorption coefficient of 0.015 dB/m. The value of transmission loss is in good agreement with the results calculated by the Marsh and Schulkin (M&S) semi-empirical expressions above 1 kHz, but is higher than the M&S results under 1 kHz, which may be due to the muddy seabed and turbid sea water in our study area. Although it is difficult to compare our research results with other studies as there is a lack of details on monitoring conditions (including pile size, hammer energy, environmental background, etc.), this paper provides a new method for underwater noise monitoring and analysis for pile driving in shallow water. [ABSTRACT FROM AUTHOR]

Continuous rigid-frame bridges are usually used in building bridges with long span and high piers. It is characterized by the consolidation between piers and beams in the middle of bridge piers and flexible bridge piers in the lower part. Among all the factors, curvature has the most obvious influence on the stress of curved continuous rigid-frame bridge, because of which, the curved beam bridge produces coupling effect of bending moment and receives complicated stress, leading to the deformation such as torsion and displacement of radial direction. No matter it is the castscaffold construction or cantilever construction, for continuous rigid-frame bridges, considering that after the long term creep of concrete, structure stress tends to be in a drop-frame state, so it is necessary to know the mechanical properties of the finished bridge. Taking the Chongqing Yangtze River Bridge as an example, this paper mainly analyzes the internal forces and deformations of a finished curved continuotus rigid-frame bridge by establishing a spatial finite element model with Midas Civil 2006 software and by changing the model's radius of curvature. The results show that as the curvature increases, the vertical deformation and torsion angle of the long-span curved continuous rigid-frame bridge are both reduced under the effect of a dead load and prestressed load, presenting mechanical properties of bridge, namely, "coupling effect of bending moment". In the model analyzed, the deformation of the bridge in the transverse direction also behaves a trend of gradual decrease with an increase in radius of curvature with the range 500-2000 m. [ABSTRACT FROM AUTHOR]

In China, rapid and continuing infrastructure growth will significantly affect the feasibility of achieving CO 2 emission reduction targets. It is uncertain whether the current infrastructure designs are consistent with the national emission targets of China, consequently posing a threat to the national commitment to reaching carbon neutrality. To illustrate the gap in achieving the emission targets with respect to bridges, we present carbon intensity reduction targets relevant to bridges by 2040. By exploring three policy–economic scenarios that combine with CO 2 emission reduction policy scenarios of the International Energy Agency and shared socioeconomic pathways, we assess the adaptability of the bridge designs to short-, medium- and long-term carbon intensity targets. We propose a new sustainability design approach based on a bridge big data set that integrates reliability, environmental impacts, and cost. We show that, under the current policy–economic scenario, more than 50% of code-based bridges would meet the five-year CO 2 emission target, whereas only one in ten thousand could meet the ten-year target under the new policy–economic scenario. Under the sustainable development policy–economic scenario, none of the bridge designs would meet the carbon reduction targets over the next 20 years. Our findings highlight that the bridges in China need to be duly considered in setting CO 2 reduction targets, and in the national move toward zero carbon, careful consideration should be given to implementing our proposed bridge sustainability design. • Three policy–economic scenarios present reduction targets for bridges to 2040 are designed. • Assess the gap of achieving CO 2 emission reduction targets for China's bridges. • Reliability, environmental impact, cost integrated in sustainability bridge design for the first time. • New sustainability design approach based on a bridge big data set. [ABSTRACT FROM AUTHOR]

With the rapid economic development over the past decades, China has witnessed a significant development in the construction of all types of large-span and extra-long sea-crossing bridges, with the maximum span up to 330 m for the box girder type, 552 m for the arch type, 1088 m for the cable-stayed type and 1650 m for the suspension type. Furthermore, two major sea-crossing bridges over 30 km long have been open to traffic. This paper describes the technical progress of Chinese bridges, including bridge design, construction, maintenance and management, as well as the application of bridge health monitoring technology. [ABSTRACT FROM AUTHOR]

The Tianjin Haihe movable bridge in China has the largest span among similar bridges in Asia. Owing to the dual characteristics of being both a bridge and heavy machinery with mechanical, hydraulic, electric and intelligent control devices, the construction of its steel box girder requires appropriate installation and control technology. Because of the stringent on-site navigation restrictions and blockage conditions, as well as mechanical characteristics during construction, a semi-supported cantilever installation and erection scheme is proposed, in which a bridge-erecting machine, temporary steel pipe support, bridge cantilever construction and other traditional methods are used in combination. Unlike traditional bridge closure technologies, new alignment closure and central locking closure control technologies are employed. The latter requires that the locking device be precisely assembled and adjusted to be horizontal for the suitable operation of the central locking equipment. The execution of this construction practice shows that the technology is feasible and effective. [ABSTRACT FROM AUTHOR]

The article discusses the role played by the water transport in pre-1959 Tibet, China. Topics discussed include the association of the study of water transport with the socio-cultural, technological, and infrastructural ideas, the difficulty in the construction of bridges due to the characteristics of the Tibetian rivers, and the first use of water craft on the plateau of the country.

This paper investigates the behavior and the failure mechanism of a double deck bridge constructed in China through nonlinear time history analysis. A parametric study was conducted to evaluate the influence of different structural characteristics on the behavior of the double deck bridge under transverse seismic motions, and to detect the effect of bidirectional loading on the seismic response of this type of bridge. The results showed that some characteristics, such as the variable lateral stiffness, the foundation modelling, and the longitudinal reinforcement ratio of the upper and lower columns of the bridge pier bents have a major impact on the double deck bridge response and its failure mechanism under transverse seismic motions. It was found that the soft story failure mechanism is not unique to the double deck bridge and its occurrence is related to some conditions and structural characteristics of the bridge structure. The analysis also showed that the seismic vulnerability of the double deck bridge under bi-directional loading was severely increased compared to the bridge response under unidirectional transverse loading, and out-of-phase movements were triggered between adjacent girders. [ABSTRACT FROM AUTHOR]

• The vehicle collision accident of the Dongguofenli Bridge is simulated to scrutinize the causes of bridge damage. • The simplified bridge model with girder is proposed for simply-supported bridges under vehicle collisions. • A nonlinear soil-pile interaction behavior is significant for the accurate prediction of vehicle-collision-induced response. • The cargo carried by heavy truck plays a key role in determining the vehicle-bridge collision response. • The ESF method in current codes without considering cargo characteristics would result in anunconservative design for a bridge pier. On May 5, 2019, a truck-tractor-trailer loaded with six coils of steel crashed into a pier column of the Dongguofenli Bridge located on the Yongjin Highway in Shengzhou, China, resulting in severe damage to the impacted pier column. Prior studies on heavy truck collision with bridge piers mainly based on finite element (FE) simulations. However, none of them examined the behavior of bridges under a real vehicle-bridge collision accident. To fill in this gap, this paper aims to reproduce the Dongguofenli Bridge vehicle collision accident and scrutinize the causes of the observed bridge damages. This is achieved by using the high-resolution simulation models for both the impacted bridge structures and the colliding heavy truck. The typical heavy truck model widely used in previous studies was employed and validated based on the experimental data. Four different methods were examined to reasonably capture the soil-pile interaction behavior during vehicle collisions. Important lessons were learned from the FE simulation that reproduced this accident: 1) the characteristics of the cargo (i.e., cargo type and cargo's fixing method) play an important role in determining the response of the bridge and 2) the damage that occurred to the bridge pier is most likely attributed to the direct impact between the bridge and the cargo (steel coils) that slipped off the truck. The analysis results also revealed that using the state-of-practice method for defining the impact force may lead to an unconservative bridge design for vehicle impact resistance. The applicability of the bridge design provisions related to vehicle impact design was also examined and the code-prescribed vehicle collision load was found to be inadequate to produce the damages that are observed in either the high-resolution simulation results or the real collision accident. [ABSTRACT FROM AUTHOR]

Abstract: Double curved arch bridges have played an important role in the history of bridge construction in China. The strengthening or retrofitting of this type of bridge has attracted a great deal of research attention in the Chinese bridge engineering community. In this paper, a novel strengthening method, i.e. the extrados section augmentation strengthening method (ESASM), has been reported. Firstly, the rationale behind this new method and the changes in internal forces after strengthening have been studied in details. A numerical optimization analysis was then performed to derive a strengthening design solution based on these results. Secondly, a trial use of this novel strengthening method in a double curved arch bridge has been reported. A numerical simulation was carried out to analyze the internal forces in the bridge both before and after it was strengthened. Results show that internal forces have been favourably redistributed after the bridge has been strengthened by using ESASM. Lastly, the adopted construction method and the strengthening effect for that project were described. [Copyright &y& Elsevier]

The proposed bridge between Chiang Khong and Houay Xay will form the remaining crucial link of the Asian Highway 3, connecting Bangkok to Kunming, a project highly anticipated in the Greater Mekong Subregion's (GMS) development. With China funding half the cost of the bridge, it signifies a strong player in the economic borderland. The article seeks to uncover the locals' thoughts and feelings of the bridge to raise awareness of ‘voices’ from the Thai-Lao border in relation to the further destinations the bridge will serve. The local perceptions of the proposed bridge are used to provide a form of comprehension of anticipatory cross-border geopolitical relations between the Thai-Lao border and China. Drawing on the concepts of critical geopolitics, anti-geopolitics and geoeconomics, it concludes by underscoring the need to listen to local perceptions at the Thai-Lao border as they signal potential ill-feelings that could jeopardise future cross-border geopolitical ties and trade. [ABSTRACT FROM AUTHOR]

Abstract: There were several tendons breakout on bottom slabs happening during construction stage of continuous pre-stressed concrete bridges in recent years in China. The paper studies one case based on numerical simulation that happened on a 47+75+47m continuous pre-stressed concrete rigidframe bridge. In this paper, both linear elastic and nonlinear inelastic analysis are developed, concrete and reinforcements stress levels before and after pre-stressed tendons stressed are compared, and the path of crack appearance are revealed by calculation. The effects of the incorrect arrangement of reinforcement during construction are also analyzed, which is proved not to be the leading reason of the failure. The outcomes of the finite element analysis indicate that oversize of the longitudinal prestressed tendons and unreasonable sizes of the bottom slab are the main reasons of the failure. Some advices to avoid similar accident are given for future design. [Copyright &y& Elsevier]

The coming Chinese specification for the steel highway bridge will adopt the design method of probability limit state on the basis of the structure reliability theory. The limit-state equation with load and resistance factors plays a key role in this method, so determining the reasonable value of the factors is the foremost work in load and resistance factor design (LRFD). The primary objective of this paper is to calibrate the target reliability index of the steel highway bridge according to current specification by the first-order secondary-moment method (JC method) and to calculate the recommended resistance factors of Q235q and Q345qD (two commonly used steels for bridges in China) by means of an optimization method. The primary and adjunctive load combinations of the steel highway bridge are taken into account, respectively. The calibrated reliability index is used to calculate the five types of loading members' factors, which are axial tensile, axial compressive, eccentric compressive, flexural, and shear member. Then the results are compared with the relative parameters in the 'Unified Standard for Reliability Design of Highway Engineering Structures' (Ministry of Transport of China GB/J50283-1999). It is demonstrated that the value put forward in this study shows precision and application well. Hence, the recommended resistance factors of the steel highway bridge can be a reference for the new specification of the steel highway bridge. [ABSTRACT FROM AUTHOR]

This paper describes the detailed design of the steel deck of Stonecutters Bridge in Hong Kong. The 1018 m main span deck and first 49·75 m of each back-span deck are steel, whereas the remaining lengths of back-span decks are prestressed concrete. The 53·3 m wide bridge deck consists of twin box girders connected by cross girders. The aerodynamic performance of the steel deck is fundamental to the overall behaviour of the bridge and the design is dominated by the dynamic effects of typhoon winds. Other design considerations including intense fatigue loading from heavy goods traffic and high summer temperatures were also influential in the design. [ABSTRACT FROM AUTHOR]

To erect a main span of a bridge across the entrance of one of the busiest container ports in the world without causing disruption is a complex operation. Stonecutters Bridge, Hong Kong, was also the second longest cable-stayed span in the world with a unique twin box deck design that was being erected through a typhoon season. Extensive preparation works were carried out from wind tunnel tests in the UK, marine simulations, new erection procedures, typhoon studies and continuous erection analysis. The main span consisted of 53 steel segments weighing between 500 and 600 t and lifted from a purpose-built self-propelled barge. The closure of the main span posed special problems with the large deflection and expansion from a 500 m cantilever, and that the closure segment was in two pieces erected at the same time. The 224 parallel wire strand stay cables were some of the longest and heaviest cables ever erected. [ABSTRACT FROM AUTHOR]

In late 1999 the Highways Department of the Government of the Hong Kong Special Administrative Region issued an open invitation to bridge designers to pre-qualify for a design competition for a road bridge across the entrance to the Kwai Chung container port. The bridge would have a span of at least 1000 m with a vertical clearance of at least 73·5 m over the full 900 m navigation channel. The purpose of the competition was to establish a reference scheme to be used as the basis for the detailed design for Stonecutters Bridge. The design competition aimed at securing a world-class design which would also be a fitting landmark and gateway for the port underlining and promoting the image of Hong Kong as a vibrant and important centre of international trade. The competition took place in early 2000 and this paper describes some of the background choosing this approach and the reasoning behind the selection of the prize-winning proposals. [ABSTRACT FROM AUTHOR]

For Stonecutters Bridge, Hong Kong, the foundation support is most efficiently provided by bored piles utilising end bearing and friction in the hard rock stratum, which is typically between 45 m and 67 m below ground level on the east side and between 48 m and 75 m below ground level on the west side. Local areas of deeper weathering are observed beneath the west tower and the adjacent back-span pier. The foundations for each pier and tower comprise a thick reinforced concrete cap supported on a grid of large-diameter, bored piles. The bored piles are socketted in rock and typically enlarged at the base up to 1·5 times the pile shaft diameter to provide resistance through both shaft friction and end bearing with no contribution from the overlying superficial deposits. The design used an iterative process to achieve compatibility between the bridge superstructure and substructure. Additional considerations for seismic loads and ship impact were also taken into account. [ABSTRACT FROM AUTHOR]

During the initial phase of the detailed design of Stonecutters Bridge, Hong Kong, site-assembled multi-strand stay cables were the preferred option owing to their ease of installation. However, when more detailed information on the wind climate at the bridge site became available during the detailed design, it became apparent that the wind effects were significantly higher than had been assumed during the review phase. As a result of this, the bridge could no longer be made to perform satisfactorily without extensive changes to the back-span superstructure unless more compact parallel wire system stays were used in the design. This paper describes the design of the stay cables, some of the tests carried out during fabrication and the geometry control of the bridge deck and towers during erection of the bridge. [ABSTRACT FROM AUTHOR]