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The blast resistance of a typical two-lane steel girder highway bridge structural system was modeled using a nonlinear finite-element approach that considered material damage, fracture, and separation. Critical blast scenarios were based on field observations of terrorist attacks on bridges in Iraq, while system failure was defined in terms of practical emergency serviceability criteria used on actual blast-damaged bridges. The blast resistance of various design parameters was assessed, including the number of girders, deck concrete strength, reinforcement ratio, slab thickness, girder and reinforcement yield strength, girder sectional dimensions, and pier column width. The presented approach uniquely quantifies structural system blast resistance in terms of the charge weight that can be applied at different locations until failure. A sensitivity analysis was conducted to determine the most influential design parameters. It was found that system blast capacity was primarily influenced by the number of girders and girder yield strength, while additional significant parameters were deck compressive strength, deck thickness, web stiffener width, and girder depth. Secondary parameters were deck reinforcement ratio, girder flange, and web thickness, while deck reinforcement yield stress was found to be insignificant. Based on the results, recommendations for improving blast resistance are provided. [ABSTRACT FROM AUTHOR]

Implementation of sustainability principles in civil engineering has increased the substantive range of bridge engineering. The consideration of additional criteria, in particular ecological and social ones, requires the design process to be supported by appropriate tools. It refers especially to large bridge elements which affect their load-bearing capacity, e.g. girders or decks. The aim of this paper is to develop an original MCDA (Multi-Criteria Decision Analysis) method as a potential tool to support a decision-making process in the selection of material and design alternatives for bridge main girders. Therefore, an advanced hybrid algorithm was created consisting of the following methods: EA FAHP+FDEMATEL+ZUM (Extent Analysis Fuzzy Analytic Hierarchy Process + Fuzzy Decision-Making Trial and Evaluation Laboratory + Zero Unitarization Method), applied at the structure design stage. The pre-dimensioned alternatives selected for analysis were then subjected to an evaluation process based on a complex set of criteria arranged in a hierarchical control structure (HCS). The algorithm has been applied based on the example of a medium span slab-and-girder bridge, assuming 6 alternative concepts of girders, different in material and dimensions. The hybrid method was compared with the EA FAHP method. Analysis results obtained based on judgments from 3 teams of Decision Makers (DM) indicate effectiveness of the proposed algorithm and its practical aspect, which may contribute to improved quality and safety of bridge structures.

This paper summarizes the blast events and resulting damage found on more than 100 bridges in Iraq caused by terrorist attacks. Most structures were two to three lanes wide and composed of a superstructure with prestressed concrete beams that supported a concrete deck. In most cases, terrorists placed charges either on the deck or at the base of columns. Typical structural system failures were due to either intermediate column failure, girder end failure, or girder end failure in combination with midspan failure. It was found that a single blast load on the deck rarely caused collapse, while three or more blast loads distributed across the deck nearly always caused deck and/or span collapse. If at least two girders remained largely undamaged, one lane of traffic could often be directed safely over the structure, allowing a heavily damaged bridge to remain in temporary use. When columns were attacked, charges placed symmetrically caused the columns to collapse downward, whereas charges placed asymmetrically caused significant lateral movement. Although most bridges were simple span, substantial resiliency was observed, where the structures could support large amounts of load even when some critical components theoretically had near-zero capacity. It was further found that separating components, even slightly, could significantly reduce blast damage propagation. Brief recommendations are given to mitigate blast damage. [ABSTRACT FROM AUTHOR]

Implementation of sustainability principles in civil engineering has increased the substantive range of bridge engineering. The consideration of additional criteria, in particular ecological and social ones, requires the design process to be supported by appropriate tools. It refers especially to large bridge elements which affect their load-bearing capacity, e.g. girders or decks. The aim of this paper is to develop an original MCDA (Multi-Criteria Decision Analysis) method as a potential tool to support a decision-making process in the selection of material and design alternatives for bridge main girders. Therefore, an advanced hybrid algorithm was created consisting of the following methods: EA FAHP+FDEMATEL+ZUM (Extent Analysis Fuzzy Analytic Hierarchy Process + Fuzzy Decision-Making Trial and Evaluation Laboratory + Zero Unitarization Method), applied at the structure design stage. The pre-dimensioned alternatives selected for analysis were then subjected to an evaluation process based on a complex set of criteria arranged in a hierarchical control structure (HCS). The algorithm has been applied based on the example of a medium span slab-and-girder bridge, assuming 6 alternative concepts of girders, different in material and dimensions. The hybrid method was compared with the EA FAHP method. Analysis results obtained based on judgments from 3 teams of Decision Makers (DM) indicate effectiveness of the proposed algorithm and its practical aspect, which may contribute to improved quality and safety of bridge structures. [ABSTRACT FROM AUTHOR]

This paper presents field measurements of the rotational stiffness of three transport vehicles equipped with different types of suspensions: leaf, combined air and leaf, and hydraulic suspensions. The rotational stiffness was determined by measuring the tilts of the vehicles when a girder or known weights were placed on them at various eccentricities. One of the tested vehicles, which featured transversely expandable wheel spacings varying from 6 to 18 ft (1.8 to 5.5 m), exhibited an increase in rotational stiffness from 78,181 to 134,584 kip-in./radian (8833 to 15,206 kN-m/radian). This paper summarizes the rotational stiffness for all the vehicles tested by the authors. The field measurements conducted have enriched the existing database on vehicle rotational stiffness in the United States. [ABSTRACT FROM AUTHOR]

In this study, the structural details of a hinge connection for steel girder segments were developed to improve the process of rapid and easy construction. In the connector developed in this study (referred to as the "speedBridge" hereafter), the compression load exerted on the upper flange is resisted by two bearing blocks in contact with each other, and the tensile force on the bottom flange is resisted by the hinge structure installed at the lower part of the steel girder. The structural behavior of the developed connection was investigated experimentally. It was shown that the developed connection details could develop an excellent connection plastic rotation of 5% rad without fracture. The test specimen developed initial stiffness in accordance with elementary beam theory for a supported beam. The maximum load reached 110% of the plastic moment of the beam. Finite element analysis was conducted to comprehend the load transfer path, and the results demonstrated that the hinge connection exhibited sufficient stiffness and strength, exceeding the bending capacity of the beam under tension without any signs of the failure modes considered in the design procedure. [ABSTRACT FROM AUTHOR]

Bangladesh is connected through bridges and many of them are experiencing damages due to the aging of concrete, weathering effect, or excessive loading. Repair and retrofitting of those bridges are becoming inevitable to make them operational. In this study, the damages of a concrete bridge have been investigated through non‐destructive tests and numerical methods. A repair and retrofitting strategy for the damaged girders has been developed using epoxy injection, shrinkage‐compensated micro mortar, and externally bonded Carbon Fiber Reinforced Polymer (CFRP) sheets. The micro mortars are injected inside the large cracks and damaged portions of the girders. The flexural zones of the girders were strengthened using U‐shaped CFRP sheets. Field load tests are also conducted to determine the achieved improvement from the repair strengthening work. Dynamic accelerometers, digital probes, and linear variable differential transformers (LVDT) were attached to determine the actual deflections of the girder before and under loading. Finite Element models (FEM) are developed to validate the field data and determine the shear and flexural resistance of the retrofitted girders. The outcomes show that the retrofitted bridge satisfies the design requirements of the AASHTO‐LRFD guidelines. [ABSTRACT FROM AUTHOR]

Steel and stainless-steel girders are widely used around the world. However, relying solely on experimental testing of these girders is not always ideal since numerical simulations can also be utilized. Although experimental tests provide accurate results, numerical simulations offer several potential advantages. For example, they require fewer resources, including human, financial, and material resources. Moreover, numerical simulations can be applied to a broader range of structural parameters and loading conditions. Nonetheless, it is crucial to conduct a verification study before carrying out any numerical simulations to ensure that the developed numerical model accurately captures the actual behavior of the girder. Consequently, this research aims to verify the accuracy of finite element models of girders created in Ansys Workbench (2020 R1) by comparing them to experimental results from previously tested girders found in literature. The verification study uses models of specimens from different sources, including specimens made of stainlesssteel, specimens with hollow tubular flanges, and stainless-steel girders with diagonal stiffeners. It is found that the finite element model can predict the ultimate strength and elastic stiffness of the girders with an average error of less than 3 and 0.4% respectively. Additionally, the model is able to simulate the deformed shape of the girders at the failure stage. Overall, the study demonstrated that the finite element model is effective at predicting the response of girders with different characteristics. [ABSTRACT FROM AUTHOR]

Deck bulb-tee girders constitute an excellent precast concrete bridge element system for medium- to longspan bridges. The precast concrete girders are transported to the jobsite, where they are placed adjacent to each other. The girders are connected using field-cast longitudinal joints. When required, a continuity diaphragm over the pier is used to create moment continuity; however, there is a risk of cracking of the field-cast joints and construction can be difficult when adjacent girders have different camber profiles. Given these challenges, adoption of the deck bulb-tee girder systems has been limited. Analytical investigation performed in part 1 of this series of papers indicated that using ultra-high-performance concrete (UHPC) can improve the performance of the field-cast joints and help overcome construction difficulties. This paper describes full-scale experimental testing performed as a follow-up to the analytical investigation. Longitudinal joints grouted with UHPC were tested under a combination of thermal and live load. A continuity diaphragm with partial UHPC was also tested under positive and negative moments over the pier. [ABSTRACT FROM AUTHOR]

Precast concrete deck bulb-tee girder systems offer an excellent choice for prestressed concrete bridges with spans of 100 fl (30.48 in) or more. These girders are placed side by side in the field and connected using longitudinal joints. The wide top flange of the girders acts as a deck, eliminating the need for a cast-in-place concrete deck and providing a solution for accelerated bridge construction. However, the longitudinal joints between the girders often crack under service loads, allowing for water and deicing chemicals to enter the system and cause corrosion. An analytical study with ultra-high-performance concrete (UHPC) longitudinal joints was performed to investigate the joint performance when subjected to thermal and live loads. A continuity diaphragm with UHPC in the top flange was also investigated for negative moment over pier. Results of the investigation suggest that the use of UHPC can improve the performance of the connections. The high bond strength of the UHPC reduces the connection length and allows for simpler reinforcement details. [ABSTRACT FROM AUTHOR]

Deterioration of the end regions of prestressed concrete bridge girders is commonly observed in the field when girders are exposed to chloride-laden water that has leaked through failed expansion joints. Because the deterioration is often localized to the end regions of the girders, reliable repair techniques can provide a means to extend girder service life, avoiding the need for immediate superstructure replacement. To evaluate different repair methods and identify key design considerations for end region repair, shear tests to failure were conducted on prestressed concrete girders extracted from a decommissioned superstructure. Three repair systems were evaluated: an externally bonded fiber-reinforced-polymer (FRP) system, a near-surface-mounted FRP system, and a concrete end block. Only the externally bonded FRP system successfully restored both the strength and initial stiffness of the girder. Although the other two methods were not successful, the tests on the repaired girders highlight important factors that must be considered when designing repairs or conducting further research. The tests also demonstrate that end region deterioration can cause significant (> 40%) reductions in strength, underscoring the importance of addressing such deterioration observed in the field. [ABSTRACT FROM AUTHOR]

In this study, the structural details of a hinge connection for steel girder segments were developed to improve the process of rapid and easy construction. In the connector developed in this study (referred to as the “speedBridge” hereafter), the compression load exerted on the upper flange is resisted by two bearing blocks in contact with each other, and the tensile force on the bottom flange is resisted by the hinge structure installed at the lower part of the steel girder. The structural behavior of the developed connection was investigated experimentally. It was shown that the developed connection details could develop an excellent connection plastic rotation of 5% rad without fracture. The test specimen developed initial stiffness in accordance with elementary beam theory for a supported beam. The maximum load reached 110% of the plastic moment of the beam. Finite element analysis was conducted to comprehend the load transfer path, and the results demonstrated that the hinge connection exhibited sufficient stiffness and strength, exceeding the bending capacity of the beam under tension without any signs of the failure modes considered in the design procedure.

A flyover builds to solve traffic problems in several areas. Girder often uses in flyover construction, but the use of Corrugated Foam Mortar Pusjatan is relatively new in Indonesia. This study aims to compare the cost and time of flyover construction using two different methods, Corrugated Foam Mortar and Girder. The comparison did for the same structural length of flyover 983.5 m. As a result, The Corrugated Foam Mortar method costs Rp. 46,463,841,131.40 and needs 201 days for completion, while the Girder costs Rp. 71,313,005,779.77 and needs 436 days. Based on the results, the Corrugated Foam Mortar method is 34% cheaper about Rp. 24,849,169,648.37 and 54% faster, with a time difference of 235 days faster than the girders. The cause of the biggest cost difference is material cost.

A transfer structure (TS) is a structure that alters the load path of the gravity loads, shifting the line of thrust laterally to a different vertical alignment. Transfer structures are introduced in buildings that feature discontinuities in some columns or walls and where a direct load path to the foundations is not possible. They usually represent major elements of the structure and their impact on building cost and construction time can be substantial. This paper presents an overview of existing transfer systems and provides guidance on their design and construction. Extensive research on buildings with transfer structures all over the world was carried out (more than 100 examples were analyzed) with the aim of developing a rational typology of these structures. The results can be broken down into five main types: BEAM, TRUSS, INCLINED STRUT, PLATE, and ARCH & TIE. [ABSTRACT FROM AUTHOR]

Pipe bridges are structures that play an indispensable role in chemical and oil plants. They support cable trays or pipe-carrying material. This study aims to identify the ideal configuration of a pipe bridge through the comparative study of girders with drop hanger and truss arrangements for three different spans. The most efficient arrangement for each span was suitably identified. Through the analysis carried out, it was then identified that the Girder arrangement is suitable for smaller spans such as 15 meters; while the truss arrangement was preferable for longer spans. [ABSTRACT FROM AUTHOR]

The current camber prediction procedure in the PCI Design Handbook: Precast and Prestressed Concrete results in variations between the design and the actual camber. These variations create difficulties in maintaining the design thickness of the bridge deck and the design longitudinal profile. This research aims at enhancing the PCI design method of estimating long-term camber and deflection of prestressed concrete girders. Field measurements included monitoring cambers for a total of 94 girders from fabrication through the erection at bridge sites. Compressive strength and modulus of elasticity were measured for several girders, and the results were compared with the design properties. The differences between the design and actual concrete properties were found to be the main reason for overestimation in camber and deflection. A modification to the PCI camber prediction method is proposed to improve the accuracy of predicting the erection camber based on field measurements and material tests on four types of bridge girders. [ABSTRACT FROM AUTHOR]

The goal of structural design is to select member sizes that are proportional to the structural geometry in order to achieve the most cost-effective design. Steel girders were typically made of webs, flanges and a number of internal stuffeners, the main objective of this research is to develop a finite element model to study the effect of the shapes and locations of openings on the behavior of hollow flange steel plate girders. In this study, seven models were analyzed in two groups. The first group study the effect of web openings shape openings on the behavior of hollow flange steel plate girders, while the second group study the effect of web openings location on the behavior of hollow flange steel plate girders. The girders are analyzed until the final failure has occurred. The results obtained from finite element analysis showed that that the absence of opening had an important effect on the ultimate load capacity. The ultimate capacity of hollow flange steel plate girder with four squares opening decreased about 5% compared to hollow flanges steel plate girder without openings.

This theoretical research used the finite element method to model full-depth precast concrete deck slabs. It examined the effects of pocket spacing and number of shear studs per pocket. Results indicated that horizontal shear strength increases with the number of pockets in both supported and continuous-span models. Load-deflection curves and slippage values were recorded and compared with experimental tests, confirming that pocket spacing is an important factor and that the number of studs and their configuration affects the load for slippage induction. The parametric study evaluated effects of shear connector sizes and various numbers of shear studs for distances of 24 and 48 in. (609.6 and 1219.2 mm) between shear pockets for simply supported bridges; however, there is a need for experimental evaluation of shear connector performance on design. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bridges are one of the most susceptible structural elements that can be viciously impacted by tsunami disaster. During the latest few tsunami hazards, a number of bridges were affected severely due to the lack of proper incorporation of tsunami forces in design guidelines. Therefore, it becomes imperative to evaluate the stability of bridges through the analysis of tsunami-induced forces on bridge structures. In the present study, laboratory experiments were carried out to quantify the exerted tsunami forces on girder model. Broken waves along with unbroken waves were considered for the analysis purpose. The maximum horizontal forces were larger for the broken waves than the unbroken waves. Results showed that the initial impact forces were larger than the hydrodynamic forces for broken waves whereas the opposite was true for unbroken waves. Measured forces on girder model, located in higher position, were larger and increased with increasing wave height. Lower girder position showed better performance than higher girder position regardless of wave height. One predictive formula was proposed to estimate the horizontal wave pressure on the seaward side of girder using as input the wave height and girder height. The normalized wave pressure increased as tsunami wave height increased. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Traditional precast reinforced concrete structures are characterised by joints of individual components executed with the use of cement grouts or mortars, or by welding reinforcement. The joints produced in this way cannot be demounted in the case of need without damaging the precast components. Demountable precast structures with a long life cycle enable repeated assembly and demounting thus contributing to the saving of the basic input resources and the environment. The main feature of demountable precast structures are patent-protected joints which allow the assembly of the precast components without the necessity of using "wet" processes. The article addresses the characteristics of a demountable girder - column joint. It presents the results of static load tests carried out within extensive experimental research. To conclude, the article specifies the benefits and the applications of demountable structures. [ABSTRACT FROM AUTHOR]

This study presented the results of an experimental program conducted on a newly proposed Full-scale Precast Post-tensioned Continuous (FPPC) girder for straddle monorail. The investigated FPPC girder represents the actual size, design and construction details for a newly designed monorail transit system (Yellow Line and Pink Line Monorail) in Bangkok, Thailand. The salient features of the newly proposed girder system include lightweight, low-cost, easy and fast construction. The newly proposed FPPC girder is mainly comprised of three reinforced concrete (RC) hollow haunched girders, four piers or supports, two pier segments, four wet joints, and four bearings at each support. The FPPC girder was constructed at the casting yard of Sino-Thai Engineering and Construction Public Company Limited (STECON), Thailand. The FPPC girder was tested under different loading conditions (such as service and ultimate loading conditions). Both service and ultimate loads were applied as two-point loadings. Service load in a monotonic manner was applied on the right exterior span (two-point), middle span (two-point), and on the left exterior span and middle span (four-point). Meanwhile, the ultimate load in a monotonic manner was applied only on the left exterior and middle span as a four-point loading scheme. The test results indicate that the behaviour of the FPPC girder under service load conditions is elastic. Further, cracking of the concrete was not observed at any location. The observed maximum deflections under service load conditions were less than the permissible limits at all locations. Further, the maximum ultimate load-carrying capacity was observed to be much greater than the design load under ultimate loading conditions. This is an indication that the design details and construction procedure of FPPC girder are appropriate and further that this system could be used effectively to construct straddle monorail transit systems. Finite element analysis of FPPC monorail bridge girder was also performed by using a computer program ATENA which is a computational tool for nonlinear engineering analysis of bridges and culverts. The finite element analysis results indicate that the computer program ATENA is well capable to predict the ultimate load carrying capacity, displacement and cracking patterns of FPPC girder.

A wooden structure for the new cafeteria of the Vocational School Center North in Darmstadt Lifelong learning in a future‐oriented environment: education, and sustainable construction with wood based on sophisticated processes, are combined in the new construction of the cafeteria. In order to make students, primary‐school children and the general public feel at home, there was close interdisciplinary cooperation between architecture, building services and structural engineering in order to get the best out of all spaces. The report describes the interdisciplinary development of the timber structure as well as the detailing and execution. The authors have already implemented a similar structure for the festival hall in Neckartailfingen as a roof structure with a 15 m span and a 6 m cantilever. The further development of the lattice‐shaped glulam beam structure for the cafeteria in Darmstadt allows for use of the supporting structure as a floor slab with a high live‐load, while satisfying the high requirements of the R90 fire resistance class. Regular grid structures have a high architectural quality; the appealing rooms which emerge are characterized by the supporting structure. In timber construction, rigid nodes of beams, or rods, are a particular challenge and require careful detailing. The report illuminates the development of details and describes how the chosen structural concept functions without rigid‐node construction. [ABSTRACT FROM AUTHOR]

Pipe bridges are structures that play an indispensable role in chemical and oil plants. They support cable trays or pipe-carrying material. This study aims to identify the ideal configuration of a pipe bridge through the comparative study of girders with drop hanger and truss arrangements for three different spans. The most efficient arrangement for each span was suitably identified. Through the analysis carried out, it was then identified that the Girder arrangement is suitable for smaller spans such as 15 meters; while the truss arrangement was preferable for longer spans.

Purpose. Recently, the demand for reuse of industrial buildings that have not been in operation for some time has been increasing in Ukraine. Herewith, quite often the design of their roof requires the complete replacement and renovation by using modern roofing materials to meet the requirements of new government standards. Therefore, the choice and justification of the rational design of steel roof on the example of a short-span industrial building (18-24 m span), which is planned to be returned to exploitation after idle time, is the main goal of this publication. The object of the analysis is an unheated building equipped with bridge cranes of a small capacity (up to 10 tons). Me-thodology. To achieve this purpose, the comparison of structural variants of a roof steel collar tie was performed. Such variants include two types of collar tie cross-section –a lattice truss and a solid I-girder. The first type was analyzed for four possible types of section of elements – double angles, a roll-welded square profile, an electric-welded round tube and a rolled round tube. The second type was analyzed for two possible types of section – rolled I-section made of normal strength steel and fabricated sections of thin-gage high-strength steel. The design variants were compared on the basis of a numerical analysis of their work using the finite element method based on the software complex SCAD for Windows. Findings. According to the research results it should be stated that for the conditions of the city of Dnipro the most cost-effective variant of the steel collar tie cross section for the short-span industrial building is the truss made of electric-welded round tubes. Also the construction of collar tie made of roll-welded square profiles or fabricated section of thin-gage high-strength steel is considered quite effective. Originality. The research presented in the publication allows estimating the possibility and economic efficiency of usage for various types of cross-sections for the collar tie of a steel non-insulated roof of the industrial building for the reconstruction conditions in the Dnipro-city. Practical value. A practical estimation of mass and cost parameters for steel collar ties of various types has been carried out, and the methodology for conducting such estimation has been substantiated.

Many bridge owners have developed new precast, prestressed concrete bridge girder sections that are optimized for high-performance concrete and pretensioning strands with diameters greater than 0.5 in. (12.7 mm). Girder sections have been developed for increased span capacities, while others fill a need in shorter span ranges. Accurate geometric properties are essential for design. Common properties, including cross-sectional area, location of centroid, and major axis moment of inertia, are generally easy to compute and are readily available in standard design references. Computation of the torsion constant is a different matter. This paper presents the methods and results of a study to determine the torsion constant for many of the modern precast, prestressed concrete bridge girders used in the United States and compares the results with values from the approximate methods of the AASHTO LRFD specifications. [ABSTRACT FROM AUTHOR]

Bridge safety is one of the most critical concerns among civil engineering fields due to its high importance. The redundancy of bridges was heavily investigated in the literature; however, they were focused on twin girder redundancy cases. Additionally, literatures were scarce in studies that focused on the improvement that should be made to achieve redundancy systems in different AASHTO I-girder types. Thus, this study focused on assessing the additional required number of tendons for different AASHTO I-girder types and spacing between them to achieve the redundancy of I-girder bridges. The additional unbonded tendons are suggested to be added externally or internally. The parameters varied in this study are compressive strength of ultrahigh-performance concrete (UHPC), spacing between girders (i.e. number of girders) and type of girders. Leap Bridge Concrete software was used to simulate the required structural modes. After performing extensive numerical analyses following AASHTO LRFD guidelines, the results have shown that in case of the removal of external I-girder, the tendons in the nearest girder need to be nearly increased by 1.85 to 2.3 times compared to the original design, depending on spacing, compressive strength, and the number of girders. On the other hand, in the case of interior girder removal, the number of tendons in the nearest two girders need to be increased by 1.24 to 1.32 times the original design. The effect of compressive strength variation of the used UHPC was negligible compared to spacing and type of girder. It is worth mentioning that all simulations in this study were verified using CSI Bridge software. [ABSTRACT FROM AUTHOR]

This paper presents a multi-functional strand capable of introducing prestressing force in prestressed concrete (PSC) girders and sensing their static and dynamic behavior as well. This innovative strand is developed by replacing the core steel wire of the strand used in PSC structures with a carbon fiber-reinforced polymer (CFRP) wire with a built-in optical Fiber Bragg Grating (FBG) sensor. A full-scale girder specimen was fabricated by applying this multi-function strand to check the possibility of tracking the change of prestressing force at each construction stage. Moreover, dynamic data could be secured during dynamic loading tests without installing accelerometers and made it possible to obtain the natural frequencies of the structure. The results verified the capability to effectively manage the prestressing force in the PSC bridge structure by applying the PC strand with a built-in optical sensor known for its outstanding practicability and durability. [ABSTRACT FROM AUTHOR]

Bulb-tee pretensioned concrete girders are widely used for bridge construction. Cracks, however, are often observed near the anchorage zones of these girders during detensioning and can grow in size during subsequent transportation. The cracks can take various forms, including inclined web cracks, horizontal web cracks, and bottom-flange Y cracks. This study used field measurements and finite element analyses to investigate the impact of debonding on anchorage-zone cracks. Strains in reinforcing bar and concrete were measured and compared in girders with various levels of debonding during detensioning. Debonding 25% of strands in 72 in. (1829 mm) bulb-tee girders and debonding 38% of strands in 54 in. (1372 mm) bulb-tee girders led to reductions in strains of 12% and 54%, respectively. Validated nonlinear analytical models were used to determine efficient numbers and patterns of strands to debond. A linear correlation can be assumed between tensile strains in Y-crack regions and prestress multiplied by the square of the horizontal eccentricity of prestress force on one side of the bottom flange. [ABSTRACT FROM AUTHOR]

The rail-cable-shifting-girder (RCSG) technique is a new erecting method for the main girders of the long span suspension bridge in rural mountain areas with poor transportation and no navigable rivers for carrying large components. The pseudo-static analysis of the shifting-girder process for this girder erecting technique is performed. The global mechanical model of the double-layer cable system in the shifting-girder process is established, by analytically modeling the main-cable, rail cable, and slings according to cable's basic assumptions. Based on the flexible cable theory, the main-cable segments are simulated as segmental catenary elements, the slings are considered as straight cable elements, the rail-cable segment that the shifting-girder trolley is moving on is simulated as multiple straight cable elements and other rail-cable segments are considered as single straight cable elements. The solving program is developed to obtain the pseudo-static responses including the forces and deflections of the shifting-girder system undergoing girder loads. Meanwhile, a global indoor reduced-scale model of shifting-girder system is designed to validate the presented theoretical results, by taking the Aizhai suspension bridge as engineering background. The results from the presented theoretical method match well with the measured experimental results of the indoor model test. The forces and deflections of the main-cable, rail-cable, and slings for the 21 working cases of erecting girder segments exhibit some specific distribution regularities. The presented theoretical method is able to correctly and effectively solve the pseudo-static responses of the RCSG system undergoing girder loads for the long span suspension bridge adopting the construction method of the RCSG technique. [ABSTRACT FROM AUTHOR]

The paper discusses the problems connected with long-term exploitation of reinforced concrete post-tensioned girders. The scale of problems in the world related to the number of cable post-tensioned concrete girders built in the 1950s and still in operation is very large and possibly has very serious consequences. The paper presents an analysis and evaluation of the results of measurements of the deflection and strength and homogeneity of concrete in cable–concrete roof girders of selected industrial halls located in Poland, exploited for over 50 years. On the basis of the results of displacement monitoring in the years 2009–2020, the maximum increments of deflection of the analyzed girders were determined. Non-destructive, destructive, and indirect evaluation methods were used to determine the compressive strength of concrete. Within the framework of the indirect method recommended in standard PN-EN 13791, a procedure was proposed by the authors to modify the so-called base curve for determining compressive strength. Due to the age of the analyzed structural elements, a correction factor for the age of concrete was taken into account in the strength assessment. The typical value of the characteristic compressive strength is within the range 20.3–28.4 MPa. As a result of the conducted tests, the concrete class assumed in the design was not confirmed, and its classification depended on the applied test method. The analyzed girders, in spite of their long-term exploitation, can be still used for years on the condition that regular periodical inspections of their technical condition are carried out. The authors emphasize the necessity for a permanent and cyclic diagnostic process and monitoring of the geometry of girders, as they are expected to operate much longer than was assumed by their designers.

This study aims to investigate the wind protective effect of wind barriers on the Lanzhou–Xinjiang high-speed railway using wind tunnel tests. Wind barriers with different heights and porosities were analyzed. Two girders, that is, a box-girder and a trough-girder, each with 1:30 and 1:8 scales were experimentally investigated. The results suggest that the protective effect of the wind barrier with a height of 4 m and porosity of 20% is better than the others. The influence of wind barriers on the aerodynamic characteristics of train vehicles and girders must be analyzed simultaneously. The aerostatic force coefficients of trains are approximately the same at different scales, and the Reynolds number effect could be neglected. [ABSTRACT FROM AUTHOR]

Link slabs provide continuity in the deck slab over the intermediate supports of multiple-span bridges where precast, prestressed concrete girders are used. Current practice recommends debonding the link slab from the girders' ends to reduce its stiffness. Steel reinforcement is consequently provided to satisfy the dead- and live-load criteria. A survey of bridges in the United States indicated that full-depth cracks still develop in the link slab and some practices are placing the link slab without debonding. Although design procedures for debonded link slabs are currently available, data related to bonded link slabs is scarce. This paper investigates the structural behavior of bonded link slabs due to dead and live loads. It examines the contribution of the stiffness of the link slab on redistribution of shear and moments. Closed-form solutions were derived for a three-span symmetrical case and a parametric study conducted based on standard American Association of State Highway and Transportation girders commonly used in the medium-span-length range. It was shown that the link slab parameters, if optimized, can strengthen the connection in the continuity zone to resist the induced loads without affecting its resisting capacity. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of fully tensioned top strands and inclusion of mild reinforcing steel on prestress losses and camber of pretensioned bridge girders. The results show that the inclusion of both fully tensioned top strands and mild reinforcing steel in the precompression zone reduced both short-term and long-term camber by 72% in the prestressed concrete bridge designs that were studied. Furthermore, the inclusion of both fully tensioned top strands and mild reinforcing steel have small but beneficial reduction in prestress losses. Prestress losses were estimated for a prestressed concrete bridge made with Type IV bridge girders spanning 103.33 ft (31.5 m). Five methods were used to estimate losses, including both the AASHTO LRFD Bridge Design Specifications approximate method and refined method. The newly developed Jayaseelan time-step method is presented and compared with other methods. The results show that all five methods estimate prestress losses that were within 2% of one another. [ABSTRACT FROM AUTHOR]

This paper presents a multi-functional strand capable of introducing prestressing force in prestressed concrete (PSC) girders and sensing their static and dynamic behavior as well. This innovative strand is developed by replacing the core steel wire of the strand used in PSC structures with a carbon fiber-reinforced polymer (CFRP) wire with a built-in optical Fiber Bragg Grating (FBG) sensor. A full-scale girder specimen was fabricated by applying this multi-function strand to check the possibility of tracking the change of prestressing force at each construction stage. Moreover, dynamic data could be secured during dynamic loading tests without installing accelerometers and made it possible to obtain the natural frequencies of the structure. The results verified the capability to effectively manage the prestressing force in the PSC bridge structure by applying the PC strand with a built-in optical sensor known for its outstanding practicability and durability.

• The long-term deformation of the CRTS III type ballastless track-32 m simply supported girder system was investigated. • The aid of the CEB-FIP 90 creep model and the UMAT subroutine, the long-term deformation calculations were established. • A finite element calculation method for the long-term deformation of the girder-track system was proposed. • This study had achieved the prediction of long-term deformation in the girder-track system. Until now, the CRTS (China's Railway Track System) III type ballastless track-girder system has been gradually used in high-speed railway engineering. However, the effect of long-term deformation of prestressed box girders on the upper track structure is often overlooked. Given the strict requirements for track smoothness in high-speed railways, an in-depth study of the long-term deformation of the CRTS III type ballastless track-32 m simply supported girder system (girder-track system) is particularly important. In this study, a refined finite element model was established for a three-span CRTS III type ballastless track- simply supported box girder system. Based on the aid of the CEB-FIP 90 creep model and the UMAT (User-Material) subroutine, the long-term deformation calculations were investigated. Furthermore, an in-depth analysis of stress and damage of the CRTS III type ballastless track under the long-term deformation of the box girder was conducted by combining concrete damaged plasticity (CDP) and cohesive zone model (CZM) constitutive models. The numerical simulated results indicated that after four years of operation, the creep camber of the box girder in the girder-track system would reach to 3.41 mm. The maximum tensile and compressive longitudinal stresses of the base plate would reach to 0.537 MPa and 11.983 MPa, respectively. Meanwhile, the maximum tensile and compressive longitudinal stresses of the self-compacting concrete layer would reach to 0.958 MPa and 2.701 MPa, respectively. In the box girder mid-span, significant damage could be observed in the edge of the two base plates near the mid-span, with a maximum compressive damage rate of 0.164 and the maximum tensile damage rate of 0.304. The research of this study has achieved the prediction of long-term deformation in the girder-track system, providing an important basis for the reliability assessment and life prediction of the girder-track system. [ABSTRACT FROM AUTHOR]