Precast Prestressed Concrete Girders Research Articles

Dynamical analysis of a 40 m span precast posttensioned concrete girder during lifting operations

AbstractCranes are employed to lift precast concrete girders during their construction. Presently, there is no recommendation for operational velocities during girder assemblage, particularly for long elements; simultaneously, several accidents have been reported during the transitory phase of girder motion. Since this mechanical problem has been examined in technical literature using a static approach, the present research study aims to investigate the dynamical behavior of a long, prestressed concrete girder by determining critical operational velocities according to crane movements. Prestressing cables' eccentricity and lifting loop position deviation were accounted for in 3D finite element simulations of a 40 m span precast prestressed concrete girder. Transient nonlinear analyses to obtain stresses and deflections were performed, so as to account for the large deformation behavior of the motion. A frequency domain approach was employed to analyze the time history results using the girder's natural frequencies obtained by modal analysis. The finite element model was developed to simulate upward, downward, and lateral girder movements. The most significant displacements and stresses were observed in the highest girder acceleration peaks, amplified by eccentricities. Safety against cracking and subsequent failure during vertical and lateral movements was ensured for crane operating accelerations of 0.02 g (v = 20 cm/s) and 0.007 g (v = 7 cm/s), respectively. Compared with the usual static analysis, for the critical case investigated, the inertial effect intensified the tensile stresses by 27 times, increased the compressive stresses by 11%, and increased the girder deflection by 3 times.

The Risk of Failure Assessment in Bina Marga Standard Designed Prestressed Concrete Girder Bridges under B-WIM Load Measurement

The use of precast prestressed concrete girder bridges in Indonesia has been increasing rapidly due to their high quality, reliability, and faster construction on site. The girder components are typically designed for a specific bridge span and can be prefabricated. The Directorate General of Highways of the Ministry of PUPR (Bina Marga) has released a standard design for prestressed concrete girder bridges with a typical span of up to 40 m. This design is based on the bridge loading standard SNI 1725 2016, which determines the live traffic load through consensus due to limited data on actual traffic load measurement results. However, the Ministry of PUPR has been implementing actual traffic load measurements using weigh-in-motion (WIM) technology to directly measure the load of passing vehicles. In this study, a risk assessment of the failure risk of a standard Bina Marga bridge with a 40-m span prestressed concrete girder type was conducted based on B-WIM load measurements. The results of this assessment indicate that the standard Bina Marga bridge has a failure risk of 1.48 x 10-4, which is smaller than the acceptable risk of failure according to the AASHTO LRFD Bridge Design Specification as referenced in SNI 1725 2016.

Load versus Strain Relationships of Single and Continuous Span Full-Scale Pre-cast Prestressed Concrete Girders for Monorail Systems

Full-scale testing of multiple span girders is scarce in the literature, often related to the complexity of loading setup and time constraints. The importance of full-scale tests is manifested in the fact that useful information regarding failure mechanisms can be obtained. In addition, important guidelines can be established for structural designers. Further, results from full-scale tests can help establish constitutive laws for various mechanisms involved in the response of actual structures. The structural performance of individual members can be assessed by monitoring their strains at service and ultimate loads. This study presents a comparison of experimentally monitored strains on longitudinal steel bars, stirrups, and prestressing tendons embedded in single and multi-span full-scale precast pre-tensioned girders. These girders were constructed and detailed to simulate the response of newly proposed straddle-type monorail girders. Single-span girders were tested under monotonic two-point service and ultimate loads, whereas multi-span girders were tested under both two- and four-point service and ultimate load. It was revealed that longitudinal steel and prestressing tendon strains monitored within single-span girders at service and ultimate loads were significantly higher than those recorded at corresponding locations in multi-span girders.

Probabilistic modelling of prestressed concrete roof girders

The paper describes several parts of complex stochastic modelling of precast prestressed concrete girders failing in shear. Experimental studies have been performed on scaled elements as well as on full-scale girders. These tests serve as basis for developing the deterministic nonlinear model and subsequent probabilistic assessment of structural resistance. The combination of nonlinear finite element method and probabilistic analysis is a strong tool for the realistic modelling of structures, but it is extremely time consuming, especially when 3D nonlinear model with many input random parameters is analysed. Therefore, sensitivity analyses have been performed and a surrogate model has been developed. Safety formats are utilized and compared with fully probabilistic approach to determine design value of ultimate capacity of girders.

Load and Deflection Recovery Capacities of PSC Girder with Unbonded PS H-Type Steel

Generally, a precast prestressed concrete (PSC) beam is used as girders for short-to-medium span (less than 30 m) bridges due to the advantages of simple design and construction, reduction of construction budget, maintenance convenience. In order to increase the span length beyond 50 m of precast PSC girder, PSC hollow box girder with unbonded prestressed H-type steel beam placed at the compressive region is proposed. The unbonded compressive prestressing in the H-type steel beams in the girder is made to recover plastic deflection of PSC girder when the pre-stressing is released. Also, the H-steel beams allow minimization of depth-to-length ratio of the girder by reducing the compressive region of the cross-section, thereby reducing the weight of the girder. A quasi-static 3-point bending test with 4 different loading steps is performed to verify safety and plastic deflection recovery of the girder. The experimental results showed that the maximum applied load exceeded the maximum design load and most of the plastic deflection was recovered when the compressive prestressing of H-type steel beams is released. Also using prestressed H-type steel as compression reinforcements in the upper part of cross section, repair and restoration difficulty and cost of PSC girders should be significantly reduced. The study result and analysis are discussed in detail in the paper.

Seismic modeling of integral abutment bridges in Illinois

Integral abutment bridges (IABs) are a common bridge type used in modern design and construction to prevent damage at the abutment seat from water, dirt, or deicing chemicals penetrating through a compromised expansion joint. Elimination of expansion joints in IABs leads to complex soil-structure-interaction limit states involving the IAB abutment and surrounding soil, as well as unique overall bridge behavior in comparison to non-IABs. Despite this different behavior, there is a lack of studies investigating overall bridge performance of IABs when subjected to seismic loads. Existing seismic IAB studies have typically investigated individual components, such as the interaction between abutment piles and soil or the behavior of superstructure-abutment connections, but the comprehensive behavior of all IAB components when subjected to an earthquake has not been evaluated in an integrated fashion. This study details an IAB model developed for dynamic analysis that simultaneously considers contributions from all critical IAB components. The seismic response of two IABs, one with steel plate girders and another with precast prestressed concrete girders, is evaluated at the design-level shaking using the developed model. The design-level shaking is provided by 20 ground motions, for a 1000-year return period hazard-level, developed for the southern Illinois city of Cairo. Results demonstrate the ability of the IAB model to capture key features of bridge seismic behavior, and they provide a framework for bridge engineers to understand IAB earthquake response and limit states, as well as support recommendations for IAB seismic design in Illinois concerning side retainer anchor bolt size and pier column size.

Development History of Underpass Construction Methods and Introduction of the Method using Precast Prestressed Concrete Girders

Development History of Underpass Construction Methods and Introduction of the Method using Precast Prestressed Concrete Girders

Assessment of the transportation route of oversize and excessive loads in relation to the load-bearing capacity of existing bridges

Transportation routes of oversize and excessive loads are currently planned in relation to ensure the transit of a vehicle through critical points on the road. Critical points are level-intersection of roads, bridges etc. This article presents a comprehensive procedure to determine a reliability and a load-bearing capacity level of the existing bridges on highways and roads using the advanced methods of reliability analysis based on simulation techniques of Monte Carlo type in combination with nonlinear finite element method analysis. The safety index is considered as a main criterion of the reliability level of the existing construction structures and the index is described in current structural design standards, e.g. ISO and Eurocode. An example of a single-span slab bridge made of precast prestressed concrete girders of the 60 year current time and its load bearing capacity is set for the ultimate limit state and serviceability limit state. The structure’s design load capacity was estimated by the full probability nonlinear MKP analysis using a simulation technique Latin Hypercube Sampling (LHS). Load-bearing capacity values based on a fully probabilistic analysis are compared with the load-bearing capacity levels which were estimated by deterministic methods of a critical section of the most loaded girders.

Simulating the response of CFRP strengthened shear-keys in composite concrete bridges

The reduction in the integral action between cast-in-situ slab and precast prestressed concrete girders in composite concrete bridges can be attributed to the increase in truck loads; increase in the allowable stress at service loads; exposure to aggressive environments; and the increase in traffic flow. It is a necessity to restore this integral action by strengthening against horizontal shear. In this paper, a finite element analysis (FEA) was performed considering 32 push off specimens using ANSYS software package to evaluate the behavior of shear-keys of composite concrete bridges. The studied parameters include: the concrete compressive strength, spacing of the shear stirrups, the carbon fiber reinforce polymer (CFRP) sheet spacing, and CFRP plate spacing, fiber angle, and anchorage length. The FEA results show that the reduced crack opening and slip in the strengthened shear-keys compared with the control specimen reflect the efficiency of the CFRP strengthening scheme. Moreover, the FEA results indicate that the CFRP composites anchorage length and angle had a notable impact on the longitudinal shear force and corresponding slip, failure mode, stiffness, and toughness. Finally, an empirical model was proposed for predicting the bond-slip behavior of shear-keys based on reliable experimental results available in literature.

An Experimental Study on the Precast Segmented PSC Girder with I-Shape and Box-Shape Cross-Section

Prestressed concrete (PSC) is a method in which prestressed tendon is placed inside and/or outside the reinforced concrete member and the compressive force applied to the concrete in advance to enhance the engineering properties of concrete member which is weak under tension. In this paper we suggested the precast PSC girder assembled with segments of portable size and weight at the factory. The segments of precast PSC girder will be delivered and assembled as a unit of PSC girder at the site. Consequently, we suggested new-type of precast segmented PSC girder with different shapes of segment cross-section (i.e., I-shape, Box-shape). To mitigate the problems associated with the field splice between the segments of precast PSC girder anchor system is attached near the neutral axis of the girder and relatively uniform compression throughout the girder cross-section is applied. Prior to the experimental investigation, analytical investigation on the structural behavior of precast PSC girder was performed and the serviceability (deflection) and safety (strength) of the girder were confirmed. In addition, 4-point bending test on the girder was conducted to investigate the structural performance under bending. From the experimental investigation, it was found that the precast PSC girder spliced with 3 and 5 segments has sufficient in serviceability and safety conditions and it was also observed that the point where the segments spliced has no defects and the girder behaves as a unit.

Some Experience from the Analysis of Existing 40 Years Old Prestressed Bridges in the North of Slovakia

The paper deals with the analysis of the chosen short-span bridges from precast prestressed concrete girders. The analysis has been performed at the Department of Structures and Bridges recently. Part of the current technical condition assessment of these structures comprised the load carrying capacity and remaining life time determined by calculation [1, 2 and 3]. The load carrying capacity was calculated in compliance with the previous Slovak standards and new European standards.

Experimental study on the structural behavior of concrete dapped-end beams

A common structural system in precast pre-stressed concrete girders with dapped ends has been intensively used in elevated viaducts recently built in Mexico City. A critical aspect of this solution resides in the possibility of a premature cracking in the reentrant corner of the dapped-end beam. An experimental research program was carried out to evaluate the performance of the present solution of the dapped end, both under service loading and ultimate design loads, and also to explore other solutions that could improve the performance in terms of the cracking of the reentrant corner.Four dapped-end beams models at a 1:3.6 scale were built and tested under vertical loads. The first specimen reproduced the solution adopted in the prototype, which was designed and reinforced according to the recommendations of the PCI Design Handbook. To the second one a longitudinal post-tension was applied, in the third specimen diagonal bars replaced part of the hangers, and the fourth was provided with both diagonal bars and post-tensioning.Experimental results allowed to conclude that, the specimens with longitudinal post-tensioning at the dapped, performed within the code requirements both under the service and ultimate loads, showed the best behavior in terms of cracking control. The strut-and-tie model proposed by Mattock provides a good prediction of the load capacity attained in the experimental specimens.

Behavior of precast prestressed concrete bridge girders involving thermal effects and initial imperfections during construction

The instability of precast prestressed concrete bridge girders during construction have been of particular concern to bridge engineers. After they are installed on bearing supports, prestressed concrete girders are immediately subjected to environmental thermal loads that may be exacerbated by fabrication and construction errors. Thus, in this research, the environmental thermal loads, which cause extremes in thermal deformations in precast prestressed concrete girders, were determined. Then a three-dimensional nonlinear finite element sequential analysis procedure was developed to evaluate the behavior of a precast prestressed concrete girder subjected to both thermal loads and geometry and support imperfections during each construction stage. This analysis indicated instability in a 30-m long prestressed concrete BT-1600 girder when total lateral deformation in the middle height of the girder at mid-span exceeded about 25cm.

Creep of UHPC in tension and compression: Effect of thermal treatment

Abstract Steel fiber-reinforced ultra-high performance concrete (UHPC) is of increasing interest for use in precast prestressed concrete highway bridge girders due to its superior durability and the potential for reducing or eliminating shear reinforcement, due to the presence of steel fibers. However, the contributions of creep, and especially tensile creep, to long-term performance must be better understood to develop appropriate design specifications. Due to practical considerations, it is also of interest to investigate the influence of varying thermal treatment, including temperatures lower than those recommended by the manufacturer (i.e. 90 °C), on the creep of UHPC. In this 1-year study, the effects of three different thermal treatment regimes on tensile and compressive creep performance of UHPC are examined, with complementary characterization by nanoindentation and scanning electron microscopy. Results show that UHPC creeps phenomenologically differently in tension and compression. Both thermal treatments examined resulted in similar tensile creep behavior, suggesting that a lower temperature applied over a longer period could effectively cure UHPC. For the non-thermally cured UHPC, a 10 μm wide region observed at the fiber/matrix interface was characterized by reductions in elastic modulus as well as greater porosity and microcracking than the bulk paste. It is suggested that the quality of the fiber/matrix interface is a major contributor to the measured increased creep of non-thermally treated UHPC as compared to UHPC treated at 60 °C or 90 °C.

A method for evaluation of longitudinal joint connections of decked precast concrete girder bridges

As bridge conditions in the United States continue to deteriorate, rapid bridge replacement procedures are needed. Decked precast prestressed concrete (DPPC) girders are used for rapid bridge construction because the bridge deck is precast with the girders eliminating the need for a cast-in-place slab. One of the concerns with using DPPC girders as a bridge construction option is the durability of the longitudinal joints between girders. The objectives of this paper were to propose a method to use a spring element modeling procedure for representing welded steel connector assemblies between adjacent girders in DPPC girder bridges, perform a preliminary study of bridge performance under multiple loading scenarios and bridge configurations, and discuss model flexibility for accommodating future field data for model verification. The spring elements have potential to represent the contribution of joint grout materials by altering the spring stiffness.

Comparison of dynamic properties of spliced and monolithic prestressed concrete box railway girders

Longitudinal splicing of precast prestressed concrete (PSC) girders has recently gained increasing support as an effective method to accelerate bridge construction. The presence of the joints in the spliced girder may alter the dynamic properties of the system. In this study, a 20 m long full-scale spliced PSC girder was fabricated and tested to identify its dynamic characteristics against a monolithically fabricated girder (monolithic girder) with the same dimensions. The experimental program involved two phases. First, the dynamic properties of the test girders were identified from a modal test. Numerical modal analyses based on three-dimensional finite element models were also performed, and the calculated modal parameters were compared with the test results. The second phase involved a characteristic decrease of the natural frequency due to the damage to each girder after the load test. This study shows that the spliced girder provides a dynamic performance comparable to that of a monolithic girder in both the uncracked and cracked states.

Obtaining optimal performance with reinforcement-free concrete highway bridge decks

This article describes an application of nonlinear finite element modeling (FEM) and analysis in the selection of design details to provide desirable performance in reinforcement-free concrete highway bridge decks. The FEM approach was used to predict the ultimate capacity and failure modes of decks considered as constrained membranes. Lateral constraint of the deck (membrane) provides extra wheel load capacity for reinforcement-free bridge decks on bulb tee wide flanged concrete girders. The wide flange precast prestressed concrete girder sections currently used in bridges result in a shorter effective span for the bridge deck between the wide girder top flanges. The failure mode of concrete decks on these girders with wheel loading is expected to be punching shear. The shear forces from the vehicle wheel loads in the reinforcement-free bridge deck are designed to be carried by compressive membrane action without using reinforcing in the concrete. The compressive membrane action is enhanced by the natural lateral stiffness of the wide girder flanges and by tying adjacent girders together with steel rods placed between the webs. An experimental study of a restrained deck element was performed to identify the failure mode and to use as a basis for verifying the nonlinear properties used in finite element analysis. A parametric study using nonlinear finite element analysis was performed to investigate the factors affecting the ultimate capacity and the failure modes of reinforcement-free bridge decks on wide flange precast girders and to provide a basis for selecting desirable design details.

Effect of Intermediate Diaphragms on Decked Bulb-Tee Bridge System for Accelerated Construction

One of the promising systems for accelerated bridge construction is the use of the decked precast prestressed concrete girders or decked bulb-tee girders for the bridge superstructure. Using the calibrated three-dimensional finite-element models through field tests, a parametric study was conducted to determine the effect of intermediate diaphragms on the deflections and flexural strains of girders at the midspan as well as the live load forces in the longitudinal joint. The following diaphragm details were considered: different diaphragm types (steel and concrete), different diaphragm numbers between two adjacent girders, and different cross-sectional areas for steel diaphragms. Five bridge models with different diaphragm details were developed, and the short span length effect on the bridge behavior was also studied. It was found that as long as one intermediate diaphragm was provided between two adjacent girders at midspan, changing the diaphragm details did not affect the girder deflection, the girder strain, and the live load forces in the longitudinal joint significantly. The effect of diaphragms on the midspan deflection was more prominent in the short span bridge; however, the reduction in the maximum bending moment by the diaphragms was more significant in the long span bridge than in the short span bridge. Specific design recommendation is provided in this paper.

Improved Longitudinal Joint Details in Decked Bulb Tees for Accelerated Bridge Construction: Fatigue Evaluation

This companion paper focuses on an investigation of improved continuous longitudinal joint details for decked precast prestressed concrete girder bridge systems. Precast concrete girders with an integral deck, which are cast and prestressed with the girder, provide benefits of rapid construction along with improved structural performance and durability. Despite these advantages, the use of this type of construction has been limited to isolated regions of the United States. One of the issues limiting more widespread use is the perceived problem with durability of longitudinal joints used to connect adjacent girders. Four full-scale slabs connected by No. 16 (#5) headed reinforcement detail using a 152 mm (6 in.) lap length were fabricated and tested. An analytical parametric study was conducted to provide a database of maximum forces in the longitudinal joint. These maximum forces are then used to determine the loading demand necessary in the slab testing due to the service live load. Static and fatigue te...

Improved Longitudinal Joint Details in Decked Bulb Tees for Accelerated Bridge Construction: Concept Development

This paper focuses on an investigation of improved continuous longitudinal joint details for decked precast prestressed concrete girder bridge systems. Precast concrete girders with an integral deck that is cast and prestressed with the girder provide benefits of rapid construction along with improved structural performance and durability. Despite these advantages, use of this type of construction has been limited to isolated regions of the United States. One of the issues limiting more widespread use is a perceived problem with durability of longitudinal joints used to connect adjacent girders. This paper presents the results of a study to assess potential alternate joint details based on constructability, followed by testing of selected details. Seven reinforced concrete beam specimens connected with either lapped headed reinforcement or lapped welded wire reinforcement were tested along with a specimen reinforced by continuous bars for comparison. Test results were evaluated based on flexural capacity, curvature at failure, cracking, deflection, and steel strain. Based on the survey and the experimental program, a headed bar detail with a 152 mm 6 in. lap length was recommended for replacing the current welded steel connector detail. DOI: 10.1061/ASCEBE.1943-5592.0000067 CE Database subject headings: Reinforcement; Joints; Bridge construction; Bridge decks. Author keywords: Lap length; Headed reinforcement; WWR; Longitudinal joint; Decked bulb tee; Accelerated bridge construction.