Precast segmental construction can shorten the construction time of the bridge and reduce the impacts on traffic and environment. Thus, this approach has been widely used in many countries. The ...relevant literature suggests that in the existing segmental precast bridges, nearly all of the centerlines of the girders are aligned with the centerline of the bridge piers. This paper introduces a wide urban viaduct comprising twin separate box girder cells using segmental prefabrication. To save space under the bridge, the bridge has only one row of piers and long cantilever crossbeams are set at the top of each pier. Additionally, the centerline of the girder and the centerline of the pier do not overlap. To prevent eccentric loading and improve the construction speed, two bridge erection gantries are used for synchronous construction. This study is a pioneering attempt at bridge construction with a precast segmental twin‐deck box girder bridge simultaneously erected with double gantries. To investigate the stress state of the whole system (crossbeam, gantries, and box girder segments) during construction and demonstrate the feasibility of the construction method, a real bridge was used. The test results provide a reference for the design and construction of similar projects.
The key issues in designing ballastless track for high-speed railway bridges are to reduce maintenance and improve track smoothness by understanding fatigue damage characteristics. This paper is ...based on the principle of bridge-rail interaction and train-track-bridge coupling dynamics, the refined simulation model of bridge-CRTS I Bi-block ballastless track system is established by using the finite element method. The longitudinal force distribution law of CWR (Continuously Welded Rail) and the dynamic response characteristics of coupling systems are studied, based on the Miner rule and S-N curve. The fatigue characteristics of ballastless track system laying on long-span bridge under the dynamic train load and the effect of ballastless track system design parameters changes on fatigue characteristics are discussed. The results show that the extreme values of longitudinal force of CWR all appear in the middle of the bridge span or near the bridge bearing, and attention should be paid to the strength checking of CRW laying on long-span bridge. Under the dynamic train load, the fatigue life curve of rail on the bridge is relatively smooth and the minimum life of rail which is laying on continuous bridge decreases from 27.1 years to 17 years that which is laying on cable-stayed bridge. The life curve of track plate laying on continuous bridge is relatively smooth, and the life curve of track plate laying on cable-stayed bridge is related to the stiffness of elastic cushion, which decreases in a stepped manner, and there will be no fatigue failure on the track plate during service. The life curve of the baseplate is related to the type of bridge, the minimum life value of the baseplate appears near the bridge bearing, and there will be no fatigue failure on the baseplate during service. Increasing the stiffness of elastic cushion can effectively improve the fatigue life of track plate, and increasing the vertical stiffness of fasteners can enhance the connection between rail and track plate and improve the fatigue life of rail. The increase in train speed will increase the dynamic stress amplitude of track structure and reduce the fatigue life of the rail.
•Estimation of vehicle-induced displacement response and influence line using radar device under moving vehicle.•Displacement calculation using simulated static load test scenario.•Estimation of load ...rating factor and load carrying capacity from moving vehicle testing.•Full-scale verification of load rating factor in a PC girder bridge using both static load test and truck pass-by test.•Displacement estimated by the truck pass-by test is reasonably accurate compared to the conventional static load test.
Efficient and reliable load-carrying capacity evaluation of deficient bridges is essential for bridge maintenance and management. Based on load-carrying capacity evaluation of an existing bridge, operator can formulate strategies and implement countermeasures such as repair, strengthening or traffic regulation. Currently, static load test is used widely for evaluation of bridge load-carrying capacity. The test, however, is often considered expensive and requires massive traffic closure that hinders frequent implementation on highway or bridges in the rural area. In this paper, an efficient method for load-carrying capacity evaluation of girder bridges based on displacement under moving vehicle is proposed. The method consists of three main procedures, namely, radar-based dynamic displacement measurement under truck pass-by test, influence line extraction, and estimation of the displacement under the static load test scenario. Based on these procedures, evaluation of load-carrying capacity is conducted following the AASHTO manual. The method was verified in numerical simulations using three-dimensional finite element model of typical girder bridge under vehicle loading. Effects of vehicle weight, vehicle speed, and road roughness on the accuracy of displacement estimation were investigated in the numerical simulations. Full-scale implementation of the method was conducted on a simply supported prestressed concrete girder bridge to investigate feasibility of the proposed method and to provide guidance for practical application. The results reveal that load rating factor of the girders can be reliably evaluated. The evaluation process was also more effective and economical than the conventional method.
•Multi-material topology optimization is used to design a steel–concrete bridge.•An efficient and elegant rigid frame bridge with a main span of 350 m is proposed.•A feasibility analysis of the ...construction process of the new bridge is carried out.•The new bridge exhibits superior techno-economic indicators to conventional bridges.
This paper proposes a novel bridge design approach based on multi-material topology optimization, which realizes the process from conceptual design to detailed design, and an innovative bridge form is obtained with the proposed approach. In the present study, the multi-material bi-directional evolutionary structural optimization (MBESO) method, which is developed from the bi-directional evolutionary structural optimization (BESO) method, is used as the algorithm which can effectively handle topology optimization problems involving multiple materials. Since the method assigns two different materials to the tension and compression members in a structure, it is particularly suitable for designing bridge structures composed of steel and concrete. A three-span bridge with a main span of 350 m is used as an example to apply the MBESO method for the topology optimization design, and a set of techniques are introduced, such as the variation of the design domain, the utilization of symmetry, the selection of the non-design domain and the consideration of multiple load cases, to obtain multiple optimization results. By comprehensively studying the functionality, ease of construction, and aesthetic properties, a competitive result is selected as the proposed conceptual design for the bridge, and then a detailed design, including an implementable construction process, is achieved and verified by finite element analysis. The comparison between the proposed bridge and other typical bridge types based on technical and economic indicators clearly shows the obvious advantages of the new type of bridge design. This research work realizes the whole process to obtain the detailed design of a new bridge type from the form-finding with the MBESO method, revealing the considerable value of applying multi-material topology optimization to the design of practical long-span bridges.
•The traffic composition and the variation over time on four grades of road in China were explored.•Statistical models of speed, axle weight, and gross vehicle weight were established.•A fatigue load ...model of vehicles was established based on a two-stage method.
Bridge vehicle load is an important parameter that is relevant to the construction and maintenance stages of a bridge. In recent years, a large number of orthotropic steel deck bridges have been built in China, and it is urgent to establish a fatigue load model that reflects the actual traffic conditions of the bridges. This study has investigated the variation of vehicles over time on four grades of road (expressway, first-class highway, second-class highway and urban main road) according to the weight-in-motion (WIM) data. Subsequently, the statistical model was established in terms of speed, axle weight, and gross weight of vehicle (GVW) acting on the four grades of road. Finally, a fatigue load model of vehicles on the four grades of road was established based on a two-stage method. The results show that (1) the speed of vehicle on the four grades of road obeys the unimodal distribution; (2) the GVW of two- and three-axle vehicles on the four grades of road belongs to the t-distribution and the log-normal distribution, respectively; (3) the GVW of four- and five-axle vehicles on expressways is a finite mixed distribution, whereas the GVW of four- and five-axle vehicles on the remain three grades of road obeys the log-logistic and log-normal distribution respectively; (4) the GVW of six- and above axle vehicles on expressways and second-class highways obeys a finite mixed distribution with two variables, whereas that on first-class and urban main roads obeys the log-normal distribution; (5) the axle weight of standard fatigue vehicles differs remarkably on different grades of roads, which is difficult to describe the fatigue damage in a uniform standard fatigue vehicle.
•Numerical simulation algorithms and material models are validated by field explosion tests.•High-reliability FE model of prototype RC girder bridge was established and the damage modes are ...revealed.•Damage modes and responses of simply-supported and continuous RC girder bridges are compared.•The minimum safe standoff distances for below-deck explosions are given for bridge protections.
During the whole service life, bridge structures potentially suffered from the threats from military conflicts, terrorist attacks and accidental explosions. The related studies on the damage modes and dynamic responses of entire RC girder bridges subjected to the explosion loadings is very limited, which is addressed through high-reliability numerical simulations. Firstly, by comparing with the experimental overpressure- and acceleration-time histories, as well as the damage modes from the explosion tests on 1/5 scaled two-span girder bridges, the validities of the material models and corresponding parameters, as well as the numerical simulation algorithms are verified sufficiently. Then, three levels of potential explosive threats, i.e., suitcase, sedan, and small moving van (the corresponding equivalent cubic TNT explosive masses are 23 kg, 454 kg and 4536 kg) specified by Federal Emergency Management Agency (FEMA) were selected to analyze the damage modes and dynamic responses of a typical four-span prototype RC girder bridge under both below- and above-deck explosion scenarios. Furthermore, the blast resistance of both simply-supported and continuous girder bridges were examined, and the minimum safe distances were proposed. It derives that, (i) for the below-deck explosion scenarios, total nine damage modes exist from small-scale spalling of concrete at the bottom of pier to the total collapse of the bridge; (ii) for the above-deck explosion scenarios, eight damage modes can be induced, including cratering and opening in deck, flexural failure of the T-girder, etc.; (iii) the continuous bridge exhibits obvious and slight enhanced blast resistance for below- and above-deck explosions than simply-supported girder bridges; (iv) small moving van can lead to the destruction of the entire bridge, the minimum safe standoff distances for suitcase and sedan bombs are 0.5 m and 3.0 m.
Bridges can be categorised by span lengths, such as short-span, medium-span, long-span and super-long-span and also by type, such as girder bridges, arch bridges, cable-stayed bridges and suspension ...bridges. This paper studies how long a span for each of these four types of bridges can be.
Abstract
Bridge scour is a natural phenomenon that can cause serious damage to infrastructure. It occurs when water flows around bridge piers or abutments, eroding the soil or sediment that supports ...them. This can lead to structural failure, which poses a significant risk to public safety. To mitigate this risk, engineers must design bridges with scour in mind, taking into account factors such as flow velocity, sediment transport, and erosion resistance. In doing so, they can ensure that our infrastructure remains safe and sustainable for years to come. Bridge scour evaluation is a crucial step to assure the structure’s safety and integrity. There are several approaches to designing, evaluating, and inspecting bridges for scour. Scour assessment is significant since it might jeopardize the bridge’s integrity. Floods scouring bed material surrounding bridge foundations are the most prevalent cause of bridge failures. Proper scour analysis is required as scour has found to be a serious threat to bridge structures since it increases the risk of collapse of bridge. Moreover, scour seriously affects the capacity of the bridge and causes structural damage. This research focusses on the scour analysis of Musiri bridge (Thanthai Periyar bridge) located on Cauvery River in Trichy. The bridge is subjected to local scour. Hydraulic Engineering Centre, River Analysis Simulation (HEC-RAS) software is used to analyze the effect of scour at different cross sections of the river, both in upstream and downstream. A planform analysis has been done across the bridge for a time period of over 10 years using open-source satellite data with the help of Quantum Geographic Information System (QGIS) software. This centre line of the river across the bridge is mapped across different years to understand the effect of scour for the period of 2013 to 2023. Remedial measures have been suggested to combat the effect of scour in the study area. Bridges are just one piece of a larger puzzle, and their construction and maintenance have environmental and social impacts that must be carefully managed. Hence, it’s important to consider the broader implications of infrastructure development and it should ensure safe and simple design of bridge constructions so that the infrastructure investments can benefit both present and future generations.
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