High Performance Concrete Girders Research Articles

Investigation of the shear behavior of ultra-high performance concrete girder by simulation approach

The present study investigates the shear behavior of the Ultra High Performance Concrete girder strengthened by steel bars and stirrups by simulation approach. Utilizing the Concrete Damage Plasticity model that involves strength reduction and nonlinear behavior of the material, 3D simulation models are established and analyzed by the commercial software Abaqus. The numerical simulation model is verified by comparing the test data to ensure reliability. Numerical simulation models were then developed to investigate the relationship of shear force with parametric studies of shear span to depth ratio, steel bar ratio and stirrups spacing. Based on the obtained results, the simulation model and test results show a good agreement. The relation between the shear capacity of UHPC girder and parametric studies was also enlightened.

Effect of concrete mixture on shear behavior of prestressed concrete girders

A total of six shear-critical prestressed concrete (PC) I-girder were tested to investigate the effect of concrete mixture types on the shear behavior of PC girders. The concrete mixtures examined were conventional concrete (CC), high-performance concrete (HPC), and self-consolidating concrete (SCC) with normal (specified fc′=41.4 MPa) and high (specified fc′=68.9 MPa) compressive strengths. Test results showed that the HPC girders exhibited a shear behavior similar to the CC girders, irrespective of the concrete compressive strength. The SCC girder with normal-strength concrete (SCC-N) showed a higher ultimate shear strength ratio (Vult/Vn) and higher ultimate displacement than the corresponding CC girder (CC-N). The SCC-N mixture was designed with a similar coarse aggregate amount but a reduced maximum coarse aggregate size compared with the CC-N mixture. The better performance of SCC-N may be attributed to a better filling ability of the SCC-N mixture than the CC-N mixture. The SCC girder with high-strength concrete showed a lower Vult/Vn than the corresponding CC girder (CC-H). The lower shear strength of the SCC girder may be attributed to the lower coarse aggregate amount (19% lower) than the CC-H girder. A shear test database of PC girders was established to investigate further the effect of coarse aggregate amount on the girder shear strength. Based on the statistical analysis, the Vult/Vn and coarse aggregate amount either showed a positive or insignificant correlation. For those groups of test data that showed positive correlation, the slopes of the linear regression of the test data showed that for a 100 kg/m3 decrease of coarse aggregate amount, the Vult/Vn decreased in average by 18.5%.

Field Testing of a Prestressed Concrete Bridge With High Performance and Locally Developed Ultra-High Performance Concrete Girders

Recent research has developed mixture proportions for ultra-high performance concrete (UHPC) using materials primary local to New Mexico, United States of America (USA). In 2017, a two-span bridge was constructed in Anthony, New Mexico, USA consisting of prestressed girders using the locally developed non-proprietary UHPC, for span one, and high performance concrete (HPC), for the second span. Field tests were conducted on the bridge approximately nine months apart to investigate the performance and behavior of the UHPC and provide baseline data for future studies and condition evaluation of the bridge. The load tests consisted of various load configurations utilizing up to four trucks weighing 267 kN on average. The load paths were designed to maximize strains along the length of the bridge and investigate transverse load distributions between girders. The measured results provide a comparison of the behavior and performance of the UHPC and the HPC girders and were also compared to the American Association of State Highway and Transportation Officials (AASHTO) predicted behaviors. This study is one of the first that compares HPC and nonproprietary UHPC bridge performance subjected to the same environmental conditions and vehicular loading. The findings of the study will aid in the development of recommendations incorporating UHPC into design provisions as well as provide meaningful information of the short and long-term performance between the two materials including durability and load distribution.

Case Studies Using Ultrahigh-Performance Concrete for Prestressed Girder Bridge Design

Ultrahigh-performance concrete (UHPC) develops very high compressive strengths and exhibits improved tensile strength and durability properties that make UHPC a promising material for bridge applications. Through case studies on typical prestressed concrete girder bridges (simple and continuous), the potential impact of implementing UHPC in New Mexico was investigated. Two existing bridges with high-performance concrete girders were redesigned using UHPC with a compressive strength of 155.1 MPa (22,500 psi) and a modulus of rupture of 8.0 MPa (1,160 psi). The redesign used a modified load factor design procedure for the Service III flexure limit state and a modified load and resistance factor design procedure for the ultimate shear limit state that considered the compressive strength, modulus of rupture, and modulus of elasticity of UHPC. Additionally, 15- and 18-mm-diameter (0.6- and 0.7-in.) prestressing strands were investigated. The use of UHPC and 18-mm-diameter (0.7-in.) prestressing strands reduced the required volume of girder concrete by up to 40%. Additionally, the contribution of the steel fibers in the UHPC significantly reduced the required shear reinforcement.

Welded-wire reinforcement versus random steel fibers in precast, prestressed concrete bridge girders

Several experimental investigations have indicated that the shear capacity of fiber-reinforced ultra-high performance concrete (UHPC) girders outperforms that of conventionally reinforced high-strength concrete girders. However, the exceptionally high material and production cost of fiber-reinforced UHPC girders limits its use in bridge applications. This paper presents the experimental work and cost analysis performed to evaluate the shear capacity and economics of using welded-wire reinforcement (WWR) in precast, prestressed high-performance concrete (HPC) bridge I-girders. The development of an economical, practical, and nonproprietary HPC is presented. Two full-scale American Association of State Highway and Transportation Officials (AASHTO) Type II girders were designed according to the AASHTO LRFD Bridge Design Specifications and fabricated using the developed mixture and Grade 80 (550 MPa) WWR. The shear testing of the 2 girders indicated that welded wire-reinforced HPC girders have shear capacity comparable to that of fiber-reinforced UHPC girders while being more economical. In addition, production of welded-wire-reinforced HPC girders complies with current industry practices and eliminates the mixing, consolidation, and curing challenges associated with production of fiber-reinforced UHPC girders.

Innovative design approach of precast–prestressed girder bridges using ultra high performance concrete

The construction of new bridges and the maintenance and renewal of aging highway bridge network using ultra high performance concrete can lead to the construction of long life bridges that will require minimum maintenance resulting in low life cycle costs. Ultra high performance concrete (UHPC) is a newly developed concrete material that provides very high strength and very low permeability to aggressive agents such as chlorides from de-icing salts or seawater. Ultra high performance concrete could enable major improvements over conventional high performance concrete (HPC) bridges in terms of structural efficiency, durability, and cost-effectiveness over the long term. A simplified design approach of concrete slab on UHPC girders bridge using the Canadian Highway Bridge Design code and the current recommendations for UHPC design is proposed. An illustrative example demonstrates that the use of UHPC in precast–prestressed concrete girders yields a more efficient design of the superstructure where considerable reduction in the number of girders and girder size when compared to conventional HPC girders bridge with the same span length. Hence, UHPC results in a significant reduction in concrete volume and then weight of the superstructure, which in turn leads to significant reduction in the dead load on the substructure, especially for the case of aging bridges, thus improving their performance.

Transfer and Development Length of 15-mm Strand in High Performance Concrete Girders

The purpose of this experimental research program was to verify that the transfer and development length of 15-mm (0.6-in) diameter prestressing strand were less than calculated by the current American Association of State Highway and Transportation Officials Specifications when used in high performance concrete bridge girders. The scope was limited to testing four AASHTO Type II girders, two made from 70 MPa and two from 100 MPa and two from 100 MPa design strength concretes. Transfer length was determined by measuring strand end slip and concrete surface strain. Development length was determined by performing eight flexure tests with varying embedment lengths. Transfer length averaged 447 mm (17.6 in.) and 371 mm (14.6 in.) for the 70 and 100 MPa concretes, respectively. The development length was found to be 2032 mm (80 in.). These values were less than those given by the current AASHTO and ACI code provisions; therefore it is recommended that current code provisions be used for pretensioned concrete girders with strengths up to 100 MPa.

Effects of Steam Curing Temperature on Early Prestress Losses in High-Performance Concrete Beams

Accurate prediction of prestress losses is a very important step in the design of a highly stressed high-performance concrete (HPC) girder and can affect the service behavior of the girder, such as deflections, camber, and cracking. Current methods for calculating prestress losses according to AASHTO and the Prestressed Concrete Institute were developed for conventional concrete. Further research is needed to determine if the current empirical equations provide an accurate estimate of prestress losses for an HPC girder. Actual prestress losses in HPC girders need to be measured and compared with the predicted losses by use of these equations. The higher the prestressing force in the girder, the larger the concrete compressive strength that is needed at the time of release of the prestressing strands. To help achieve the higher release strength, the precast plants have been using longer curing times. Many precast plants are using steam curing to increase the curing rate. A better understanding of the effects of this heating on HPC is needed. An optical fiber monitoring system was designed and built into a three-span HPC highway bridge. The Rio Puerco Bridge, located 15 miles west of Albuquerque, New Mexico, is the first bridge to be built with HPC in New Mexico. The bridge has three spans each with a length of 29 to 30 m. It is designed to be simply supported for dead load and continuous for live load. HPC was used for the cast-in-place concrete deck and the prestressed concrete beams. A total of 40 long-gauge (2-m-long) deformation sensors, along with thermocouples, were installed in parallel pairs at the top and bottom flanges of the girders. The embedded sensors measured temperature and deformations at the supports, at the quarter spans, and at midspan. Measurements were collected during beam fabrication (casting of the beams, steam curing, strand release, and storage), bridge construction, and servicing. The data collected were analyzed to calculate the prestress losses in the girders, to compare the losses with the predicted losses by available code methods, and to get a better understanding of the properties and behavior of HPC.