Segmental Girder Research Articles

Bridge Deck Transverse Stress Analysis of Arch Tower Cable-Stayed Bridge with Steel Box Girder

In the engineering background of zhijang bridge, shell finite element model of steel box girder segment was established by the ABAQUS finite element program. The transverse stress of the bridge deck was analyzed by two cases of body cable and external cable, and the transverse stress of the bridge deck caused with deadweight and vehicle load was been compared. Conclusions obtained mainly include: the transverse stress of the bridge deck induced by the four cases were not large, if lateral inclination of stay cable was not particularly large, the transverse stress of the bridge deck caused by space cable can not be given special consideration.

Nonlinear simulation of lattice girder segment tests

Lattice girders often replace conventional steel rib arches as a means of temporary support in tunnels and often have a comparative advantage over the latter mainly due to their lighter weight. Their use is directly related to the application of a shotcrete layer, in which they are encased, forming thus a composite structure that has been proved successful over numerous projects worldwide. However, any loads from the surrounding rock before shotcrete placement or hardening, have to be carried out by the lattice girder itself. Such loads may be concentrated in parts of the girder, due to sliding or falling blocks, detaching strata, reacting ground, etc. Their effects on it, which are nonlinear, necessitate analysis with detailed models; their adequacy should be experimentally validated. Therefore, a series of loading tests is conducted on simply supported arched lattice girder segments, in which the load is induced horizontally at the roller support. These tests are then simulated numerically with various 3D models. The appropriateness of the latter is thus checked by comparing the ultimate loads and deflections, which were found to be limited by buckling.

Behavior of bridge girders with corrugated webs: (I) Real boundary condition at the juncture of the web and flanges

In this paper, the real behavior at the juncture between the corrugated web and flanges of bridge girders is studied. An elastic bifurcation buckling analysis is carried out using ABAQUS computer package for corrugated webs with simple (S) and fixed (F) boundary conditions at their juncture with the flanges. The dimensions of the generated corrugated webs are assumed based on the average dimensions of the available bridges with corrugation webs. The principle aim is to firstly compare them with each other. Secondly, the critical shear buckling strengths of the corrugated webs with both boundary conditions are compared with the interactive shear buckling strength formulae available in the literature. The paper is then extended to compare girder segments composed from corrugated webs and flanges with corrugated webs with well-defined boundary conditions; simple (S) and fixed (F). Based on the numerical results, the relative critical shear stress of the corrugated webs of simple juncture to that of the corresponding fixed boundary condition has an average value of 0.96. The comparison with the available interactive shear buckling strength formulae shows that the 1st-order interactive buckling strength is suitable for the case of corrugated webs with simple-juncture, while it is unconservative for the case of fixed-juncture corrugated webs. Hence, a new interactive shear buckling strength formula is proposed for the case of fixed (F) juncture in the current paper. The results as well obviously indicated that when the flanges are rigid enough (tf/tw⩾3.0), the girder segments exhibit shear failure mechanisms. Whereas, if the corrugated web plates are relatively rigid (tf/tw<3.0), the strengths of the girders become controlled by the deformation of flanges. Finally, it is found that the realistic support condition at the juncture is nearly fixed.

Research on Integral Lifting Continuous Steel Box Girder Bridge Construction Technology

Due to over length and weight of the girder segment, the main bridge steel box girder of Chongqi Bridge adopts large segment integral lifting erection method; two sets of large floating cranes are needed for hoisting. According to the water environment condition at site, select the lifting equipments to research on; conduct restrict checking on the lifting weight, height and amplitude; new automatic balance type lifting sling structure form is adopted during lifting erection to make sure the stress on each lifting point is balanced; conduct optimization design onto the lifting points; aimed at lifting erection of large segments, use ansys to establish large solid simulation model for finite element analysis so as to guarantee safety of steel box girder structure during lifting erection of large segment.

Performance evaluation of dry and epoxy jointed segmental prestressed box girders under monotonic and cyclic loading

A large number of post-tensioned prestressed concrete segmental bridges are being constructed worldwide. Use of different materials and shear keys will have varying effects on the performance of segmental girders even during the service load. The type of joints, quality of joint, degree of mechanical actions and the joint materials will contribute to the variation in the behaviour of the segmental girders. Hence, the need for investigation on the epoxy jointed segmental box girder and dry jointed segmental box girder becomes necessary. This paper presents the experimental investigations carried out in laboratory environment on a scaled model of a simply supported precast post-tensioned box-girder bridge deck that is cast using segmental construction method. Performance of box-girders with dry and epoxy joints is evaluated under static and cyclic loading. It is observed from the results that the flexural strength of dry jointed specimen is less than the epoxy joint due to high concentration of rotation and deflection at individual joints of segmental girder. Upto design load, segmental box girder specimen with dry and epoxy joints behaved like monolithic beam. However, it is found from the study that first joint opening load of the dry jointed specimen is 27% less than the epoxy jointed specimen due to lack of resistance to tension between the joints. Due to high concentration of rotation and deflection at individual joints in the dry jointed specimen, the maximum load and failure load are 8.6% and 16.7% less than that of the epoxy jointed specimen. The study will help in understanding the role of type of joint and the material used on the performance of the segmental bridges.

Behavior of Horizontally Curved I-Girders during Lifting

AbstractSeveral stages of performance need to be considered during the design of curved I-girders, including both the construction stage and the in-service conditions. Girder stability during the early stages of construction can be difficult to assess because the girders, at times, have little or no bracing present. One stage when there is no bracing present occurs when the girders are picked up from the ground or transport trucks by cranes and lifted into place. To better understand girder response during this critical stage, field studies were conducted on horizontally curved I-girders to measure rotations and stresses during the lifting process. This paper provides details of a semianalytical solution to predict the buckling and deformational responses of straight and curved girder segments during lifting. The deformations can be compared with rotational limits that were established to minimize problems with making connections to previously erected girder segments. The total rotational deformations of ...

Analysis of Thermal Environmental Effects on Precast, Prestressed Concrete Bridge Girders: Temperature Differentials and Thermal Deformations

AASHTO specifications provide vertical thermal gradients for the thermal design of precast, prestressed concrete bridge girders. However, the thermal behavior of the girders pertains to not only vertical thermal movement but also lateral thermal movement. Thus, a one-year experimental and analytical study was conducted on a prestressed concrete BT-1600 girder segment to investigate both the vertical and lateral thermal gradients with variations in environmental conditions. The vertical thermal gradients were compared using current AASHTO recommendations. In addition, this study evaluated the lateral thermal gradients, which are not provided in the specifications, to propose a second-order curve. To determine the magnitudes of the thermal gradients in different environmental conditions, this study has developed equations that calculate the maximum vertical and lateral temperature differentials from daily climatic information. Results of the study showed that the predicted temperature differentials provided good agreement with the measured values. Finally, thermal deformations induced by the vertical and lateral thermal gradients were evaluated using an analytical method derived from one-dimensional beam theory.

The Construction of Geogeum Bridge with Large Segment

The Geogeum Bridge is a part of a fixed connection from Geogeum Island to Sorok Island located in the southernmost part of Korean peninsula. This bridge carries a two-lane national highway and has a total length of 2028 m, which is composed of a 912 m approach bridge and a 1116 m main bridge.The bridge girder is a 6 m high composited truss girder with a carriageway on the upper concrete deck and a walk and bicycle path on the lower steel deck. The pylons are diamond-shaped concrete structures with a height of 167,5 m. The cables have been arranged in bundles, which are believed to create a visual appearance similar to rays of sunlight penetrating through the clouds. The stay cables for each pylon are arranged in three bundles in one central plane, anchored at the top of the bridge girder and at steel anchorage boxes in the center plane of the pylons.The prefabricated 72 m large girder segments including concrete deck were lifted up and placed on temporary support on jack-up barges by using a floating crane. Seven stays in each bundle were stressed all together. Based on this construction method, it took nine months for construction. Compared with a traditional erection method using derrick crane, it is believed that the chosen method with large segment is superior in terms of construction speed and minimizing the amount of work at site.

Prediction of material coupling effect on structural damping of composite beams and blades

The present paper investigates the effect of material coupling on static and modal characteristics of composite structures. Incorporation of stiffness and damping coupling terms into a beam formulation yields equivalent section stiffness and damping properties. Building upon the damping mechanics, an extended beam finite element is developed capable of providing the stiffness and damping matrices of the structure. Validation cases on beams and blades demonstrate the importance of all stiffness and damping terms. Numerical results validate the predicted effect of material coupling on static characteristics of composite box-section beams. The effect of the full coupling damping matrices on modal frequencies and structural modal damping of composite beams is investigated. Box-section beams and small blade models with various ply angle laminations at the girder segments are considered. Finally, the developed finite element is applied to the prediction of the modal characteristics of a 19m realistic wind-turbine model blade.

Measurement Techniques of Precasting the No.4 Nanjing Yangtze River Bridge’s Segmental Girders by Short-Line

Based on the example of the No.4 Nanjing Yangtze River Bridge, the construction technics of precasting segmental girders by short-line is introduced. And the way of plant deformation monitoring as well as the establishment of horizontal and vertical construction control network in the precast plant are expatiated on. In addition, the measurement techniques during the installation of the fixed-mold, unfixed-mold, lineshape control techniques of the segmental girders, as well as the error correction theories during precasting process are discussed in particular. The short-line is successfully applied to the No.4 Nanjing Yangtze River Bridge, which shows its practical value in precasting segmental concrete bridges.

Engineering Practice of Segmental Assembly in Large Spancurved Bridge by Scaffolds

Part of Xiping railway south cave temple bridge segments are on easement curve. considering the project time limit and construction difficulties of large span curved bridge, the construction team adopted 64m soffit scaffolding composite column structure to assemble the precasted box girder segments ,this method can better solve the technical problems of nonuniform stress distribution in transverse beam and upright tubes of the bracket. Therefore, this paper introduces in details the bracket structure as well as the key construction technologies of segmental beam rand bracket. the experience can provide good reference for similar engineering.

Investigation of Extreme Environmental Conditions and Design Thermal Gradients during Construction for Prestressed Concrete Bridge Girders

Current AASHTO specifications provide engineers with a temperature gradient across the depth of the cross section to predict the vertical thermal behavior of bridges. This gradient is based on one-dimensional heat flow and does not account for change in the cross section, as found in prestressed concrete girders, nor does it account for thermal effects on the sides of the girder. Furthermore, the current specifications do not provide the transverse temperature gradient that is needed to predict the lateral thermal behavior of the girders, especially during construction, before the placement of the bridge decks. To determine the transverse and vertical temperature gradients in prestressed concrete girders, experimental and analytical studies were conducted on a prestressed BT-63 concrete girder segment. The analytical results were found to be in good agreement with experimental measurements. The analytical model was then used to determine the seasonal temperature gradients in four standard PCI girder sections at selected cities in the United States. On the basis of these findings, vertical and transverse temperature gradients were developed to aid engineers in predicting the thermal behavior of prestressed girders during construction.

Damage identification in beam-type structures using pseudo strain energy density and grey relation coefficient

Based on pseudo strain energy density (PSED) and grey relation coefficient (GRC), an index is proposed to locate the damage of beam-type structures in time-domain. The genetic algorithm (GA) is utilized to identify the structural damage severity of confirmed damaged locations. Furthermore, a systematic damage identification program based on GA is developed on MATLAB platform. ANSYS is employed to conduct the finite element analysis of complicated civil engineering structures, which is embedded with interface technique. The two-step damage identification is verified by a finite element model of Xinxingtang Highway Bridge and a laboratory beam model based on polyvinylidens fluoride (PVDF). The bridge model was constructed with 57 girder segments, and simulated with 58 measurement points. The damaged segments were located accurately by GRC index regardless of damage extents and noise levels. With stiffness reduction factors of detected segments as variables, the GA program evolved for 150 generations in 6 h and identified the damage extent with the maximum errors of 1% and 3% corresponding to the noise to signal ratios of 0 and 5%, respectively. In contrast, the common GA-based method without using GRC index evolved for 600 generations in 24 h, but failed to obtain satisfactory results. In the laboratory test, PVDF patches were used as dynamic strain sensors, and the damage locations were identified due to the fact that GRC indexes of points near damaged elements were smaller than 0.6 while those of others were larger than 0.6. The GA-based damage quantification was also consistent with the value of crack depth in the beam model.

Crack Width Formula for Transversely Post-Tensioned Concrete Deck Slabs in Box Girder Bridges

Cracking in prestressed concrete members is very critical because it directly affects not only serviceability, but also the durability of prestressed concrete structures. However, test data on the cracking behavior of prestressed concrete structures, especially on the box girder bridges, are very limited. The purpose of this study is to investigate cracking behavior and crack width of transversely prestressed concrete decks in box girder bridges, which have been frequently adopted in common practice for the design of deck slabs in box girder bridges. For this purpose, full-scale box girder segments were fabricated and tested. Major test variables include magnitude of precompressive stresses and prestressing steel ratios. The crack widths at the bottom surface of deck slabs were measured automatically according to the increase of applied loads. Strains of prestressing strands and nonprestressed reinforcing bars were also measured during the loading process. Bond characteristics of post-tensioned prestressing strands were identified from the relation between prestressing steel strains and nonprestressed ordinary reinforcing bar strains under the same loading conditions. The bond effectiveness of prestressing steel was then obtained from these test data. The effective circumferential perimeter of multiple strands in a duct that is bonded to concrete is derived and used to determine the crack width. A realistic formula for predicting crack width of prestressed concrete deck slabs was derived in terms of effective combined reinforcement ratio and the reinforcing bar stress after decompression. The proposed equation and test data agrees very well. It is seen, however, that the existing crack width formulas for general flexural beams show large deviations from the present test data of box girders and are not directly applicable to the top slabs of box girders due to different geometries. The proposed equation may be a good base for the realistic analysis/design of prestressed concrete deck slab structures.

Full-Scale Load Test of a Sand-Jack

The results of a laboratory load test performed on a particular type of steel sand-jack are presented. A sand-jack is a sand-filled containment frame placed atop falsework to temporarily support abutting concrete bridge-girder segments prior to posttensioning. The girder segments bear directly on a timber “plunger,” which in turn is supported on the sand bed. After construction, the sand is removed, causing the timber plunger to drop, thereby removing support from beneath the finished girder. The falsework may then be easily disassembled. Also presented are the results of a finite-element analysis performed to determine the lateral pressure exerted by the sand bed corresponding to the experimentally obtained displacements of the containment frame. The results provide insight into the capacity and performance of the sand-jack assembly, and guidance to the engineer in determining appropriate design pressures.

Innovative Design and Erection Methods Solve Construction of Rock Cut Bridge

Transportation difficulties, elimination of the center pier and environmental restraints presented a major design-construction challenge for this nearly 200 ft (61 m) long bridge in a mountainous region of Washington State. The solution was to divide the girder into three 63 ft (19.2 m) pretensioned bulb-tee girder segments and transport them 150 miles (240 km) to a staging area near the bridge site. There, the segments were spliced and post-tensioned to give a total girder length of 190 ft 6 in. (58.1 m). The girders were then hauled to the bridge site where they were guided into position with a launching truss and two cranes. Construction time took only 3 1 /2 months. This article discusses the project constraints, structural design, production, transportation, splicing and final erection. The highlights of the project are narrated from the perspective of the structural designer and precaster.

Analysis of curved multicell box girder assemblages

A method of analysis is proposed for curved multicell box girder grillages. The method can be used to analyze box girder grillages comprising straight and/or curved segments. Each segment can be modelled by a number of beam elements. Each element has three nodes and the nodal degrees of freedom (DOF) consist of the six DOF for a conventional beam plus DOF to account for torsional warping, distortion, distortional warping, and shear lag. This element is an extension of a straight element that was developed earlier. For a more realistic analysis of the intersection regions of non-colinear box girder segments, the concept of a rigid connector is introduced, and the compatibility requirements between adjoining elements in those regions are discussed. The results of the analysis showed good agreement with the shell finite element results, but the proposed method of analysis needs a fraction of the time and effort compared to the shell finite element analysis.

The Chesapeake and Delaware Canal Bridge Design-Construction Highlights

This award-winning $58 million, 4650 ft (1417 m) long structure is the first major all-precast, prestressed concrete segmental cable-stayed bridge built in the northeast United States. Situated on the new state relief route (SR-1) near St. Georges, Delaware, the bridge will be a big step forward in alleviating traffic congestion on this important transportation corridor. This article will concentrate on the 1650 ft (503 m) cable-stayed portion of the the project which has a main span of 750 ft (229 m). A major feature of the design is the use of precast delta frames, trapezoidal box girder segments, box pier segments and piles - all precast components were barged 180 miles (290 km) to the bridge site. The innovative design features and new construction techniques contributed to making this bridge into a very efficient and economical structure. The author presents the conceptual design and structural design features of the bridge while discussing the production, transportation, and erection aspects of the precast concrete segments.

Design-Construction of Esker Overhead

The Esker Overhead is a 164 ft (50 m) simmple span highway bridge, located on a constrained remote site in Northwestern British Columbia, Canada. To promote competitive bidding, alternative designs were developed in steel and precast, prestressed concrete with an option to construct the precast girder as a field post-tensioned segmental girder. A standard precast l-girder form was used with cast-in-place abutment diaphragms to accommodate post-tensioning anchors. The segmental option allowed the use of standard 45 ft (14 m) transport trucks and a single crane to erect the 31 ton (28 tonne) girder segments. The segmental concrete girder option saved the owner $137,325 (Canadian) over the alternate steel design on a total bridge bid of $1,000,000. This article describes the design, production, transportation and erection highlights of the project.

Measurements of mechanical properties of superstructures materials for the CFFF syperconducting MHD magnet

Argonne National Laboratory is constructing a large superconducting MHD magnet to be used in the Coal-Fired Flow Facility (CFFF) at the University of Tennessee Space Institute. Measurements of the mechanical properties of all the materials used in the superstructure (bore tube, cast flanges and deposited weld metal, cast girder segments, aluminum girders, tie plates and connecting pins) have been performed. These measurements consisted of tensile strength, yield strength, % elongation, and reduction of area at 295, 76 and 4 K. Charpy "V" notch impact tests at 23 K were used for material acceptance with additional impacts done at 76 and 295 K. To verify ductility at the 4 K operating temperature, elastic-plastic J-integral fracture toughness tests at 295, 76 and 4 K along with associated fatigue crack growth rate data were generated. Results of these measurements are discussed.