Search

The purpose of this document is to present preliminary design procedures for bridge superstructures that are made partially or completely of precast concrete. This document deals with continuous and simply supported superstructures, used in integral or nonintegral bridges. The document is intended for engineers with limited experience who will find it an instructive detailed guide to carry out conceptual design of superstructures of these types. Additionally, it is intended for experienced engineers who are interested in learning how different countries solve similar conceptual design problems. Finally, it is intended to enrich the knowledge of precasters everywhere, to be able to enhance their own designs with ideas and methods from many different countries.

Ultrahigh-performance concrete (UHPC) offers significant potential to address a variety of needs in bridge design, construction, and performance enhancement. Bridge owners have shown willingness to embrace novel solutions that could address specific challenges related to the cost, speed of construction, durability, and service life of their projects. There are hundreds of bridges worldwide that, largely in the past decade, have utilized UHPC. These applications range from minor field-cast closures to precast segments for long-span bridges to kilometer-long bridge deck overlays on a signature structure. The objective of this paper is to promote the application of this class of cementitious material in bridge engineering by presenting the progress that has been made in different regions of the world in the past two decades. Today, UHPC is being widely used in Malaysia to design and construct many bridges of different types and spans as they build out their roadway network. In South Korea, the unique characteristics of UHPC are being utilized to advance the state-of-the-art in long-span bridges. The French were early adopters and pioneers in building a strong foundation for using UHPC in a variety of bridge applications. In Switzerland, UHPC is employed to address major bridge rehabilitation needs. The United States bridge sector has embraced UHPC for a variety of field-cast connections. Current research and development efforts are promoting the use of UHPC in major rehabilitation projects and construction of primary bridge components. The adoption of UHPC solutions into the bridge sector is progressing rapidly because of the unique opportunities provided by the strength and durability of the material. It is expected that additional innovations and refinements of solutions will occur as knowledge of the material proliferates. (C) 2020 American Society of Civil Engineers.

This study evaluates the environmental impacts of a newly designed precast Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) cantilever retaining wall as a sustainable alternative approach compared with the conventional precast Reinforced Concrete (RC) cantilever retaining wall. Nowadays, according to the shocking reports of many researchers worldwide global warming is one of the most devastating problems of human being. To date, lots of research has been undertaken in the concrete industry to tackle this issue through reducing the environmental footprints of our structural designs. In this regard, UHPFRC technology offers substantial benefits through efficient use of materials as well as optimization of the structural designs resulting less CO_2 emissions, Embodied Energy (EE) and Global Warming Potential (GWP). UHPFRC as a sustainable construction material is mostly appropriate for the use in the fabrication of precast members such as precast concrete cantilever retaining walls. This study demonstrates the overview of the designed precast concrete cantilever retaining wall manufactured from UHPFRC and its Environmental Impact Calculations (EIC) versus the conventional precast RC cantilever retaining walls. Based on the EIC results, the precast UHPFRC cantilever retaining walls are generally more environmentally sustainable than those built of the conventional RC with respect to the reduction of CO_2 emissions, EE and GWP. In summary, the precast UHPFRC cantilever retaining wall proposed in this study is an alternative sustainable solution compared with the conventional precast RC cantilever retaining wall which can be used in many civil engineering projects.

One of the main breakthroughs in the concrete technology in the 20th century was the development of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) as a new generation of sustainable construction material. This paper is presented in two parts. The analysis and design procedures as well as the Environmental Impact Calculations (EIC) of the precast UHPFRC cantilever retaining walls as a sustainable alternative approach to conventional precast Reinforced Concrete (RC) cantilever retaining walls were presented in the first part (Part I) of this paper. In this part (Part II), the reliability of the precast UHPFRC cantilever retaining walls were evaluated through full scale experimental testing. In the experimental tests, four full-scale UHPFRC wall specimens with the dimensions of 2.5 m in height, 2 m in length, and 2 m in width were cast. The area of the steel bars used in the wall stem of the specimens, and the volumetric ratio of the steel fibers used in the UHPFRC mix design were the test parameters. The experimental results proved that the precast cantilever retaining walls manufactured from UHPFRC as a sustainable alternative solution has superior properties in all aspects compared to the conventional precast RC cantilever retaining wall.

Ultra-high Performance Fiber Reinforced Concrete (UHPFRC) is a new generation of cementitious based construction material developed in the mid 1990s that its unique characteristics such as high durability and impermeability, negligible shrinkage/creep and high impact resistance lead to almost maintenance free and direct enhancement of the life-span of a structure. UHPFRC is an ecofriendly and environmentally green construction material which has the capacity to compete not only with conventional Reinforced Concrete (RC) or prestressed concrete design, but it is also able to compete with conventional steel design. This paper is presented in two parts. The first part (Part I) of this paper presents the analysis and design procedures of the precast UHPFRC cantilever retaining walls as a sustainable alternative approach to conventional precast RC cantilever retaining walls. Further, the Environmental Impact Calculations (EIC) of the precast UHPFRC cantilever retaining walls were compared against the conventional precast RC cantilever retaining walls as the benchmark. The second part (Part II) of this paper evaluates the reliability of the precast UHPFRC cantilever retaining walls through experimental tests on full scale UHPFRC wall specimens. The EIC results proved that cantilever retaining walls fabricated from UHPFRC are generally more environmentally sustainable than those built of the conventional RC with respect to the reduction of CO2 emissions, Embodied Energy (EE) and Global Warming Potential (GWP). Finally, advantages of the precast UHPFRC cantilever retaining walls versus the conventional precast RC walls were presented.

Strut-and-tie model (STM) has been recommended by many codes and standards as a rational model for discontinuity regions in structural members. STM has been adopted in ACI building code for analysis of reinforced concrete (RC) deep beams since 2002. However, STM recommended by ACI 318-11 is only applicable for analysis of ordinary RC deep beams. This paper aims to develop the STM for CFRP strengthened RC deep beams through the strut effectiveness factor recommended by ACI 318-11. Two sets of RC deep beams were cast and tested in this research. Each set consisted of six simply-supported specimens loaded in four-point bending. The first set had no CFRP strengthening while the second was strengthened by means of CFRP sheets using two-side wet lay-up system. Each set consisted of six RC deep beams with shear span to effective depth ratio of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00.The value of strut effectiveness factor recommended by ACI 318-11 is modified using a proposed empirical relationship in this research. The empirical relationship is established based on shear span to effective depth ratio.

In recent years premature deterioration of concrete structures due to salt damage has become a serious social problem. Repair and strengthening in order to improve the durability of these structures has become critical. Therefore ultra high performance concrete (UHPFC) properties in terms of durability and strength are fully exploited in rehabilitation and strengthening. This study was performed to evaluate the bond strength between UHPFC and Normal Concrete (NC) substrate; Slant shear tests were performed to quantify the bond strength in shear, split tests conducted to evaluate the bond strength in indirect tension. The results showed that UHPFC has excellent interlocking with the surface of NC substrate, and then gives bond strength greater than the strength of NC substrate. Abstract In recent years premature deterioration of concrete structures due to salt damage has become a serious social problem. Repair and strengthening in order to improve the durability of these structures has become critical. Therefore ultra high performance concrete (UHPFC) properties in terms of durability and strength are fully exploited in rehabilitation and strengthening. This study was performed to evaluate the bond strength between UHPFC and Normal Concrete (NC) substrate; Slant shear tests were performed to quantify the bond strength in shear, split tests conducted to evaluate the bond strength in indirect tension. The results showed that UHPFC has excellent interlocking with the surface of NC substrate, and then gives bond strength greater than the strength of NC substrate.

B-Regions are parts of the structure in which Bernoulli's principle of straight-line strain is used. D-Regions are parts of the structure with a complicated variation in strain. In essence, D-Regions contain the parts of structure which are near to the concentrated forces or steep changes in geometry which are so-called geometrical discontinuities or static discontinuities. Strut-and-Tie Model (STM) is one of the best models to analyse the D-regions. Nevertheless, according to the existing literature, there are still some challenges about STM which are addressed in this paper. STM and its details are investigated to show its common challenges presents some recommendations to overcome these challenges. According to this review, the major challenges in STM are related to the strut effectiveness factor, static uncertainties of STM, strain compatibility, and anchorage requirements in STM. The scope of this research is confined to the two dimensional STM.

As a rule of thumb, the interfacial bonding between deteriorated concrete structures with a newly overlay repair material is one of the most important factors for structural functionality and safety as well as durability performance. In order to acquire an enhanced resistance against penetration of harmful substances, a good and effective bonding is necessary at the concrete interfaces. The objective of this study is to examine experimentally the mechanical properties and permeability characteristics of the interface between normal concrete (NC) substrate which represents old concrete structures and an overlay of ultra high performance fiber concrete (UHPFC) as a repair material. The mechanical interfacial bond characteristics were assessed using the slant shear and splitting tensile tests to quantify the influence of the differently roughened substrate surfaces. On the other hand, the permeability characteristics were evaluated by means of the rapid chloride permeability, gas and water permeability tests. The results show that the newly overlay UHPFC achieves high bond strength and bonds efficiently with the NC substrates. The specimens with sand blasted substrate surface give the best interfacial mechanical bonding in comparison to other types of surface preparation. The permeability tests proved that the interfacial bonding is very good and efficient which significantly improve the impermeability of the composites, and this was clearly shown by the SEM micrograph of the interface. Hence, it is envisaged that the use of UHPFC concomitant with appropriate surface preparation of the substrate should be able to provide effective and durable concrete repair.

While the database of tests on shear in reinforced concrete members without stirrups is extensive, the pool of test data for fiber-reinforced specimens is limited. Fewer still are tests undertaken on high-performance fiber-reinforced concrete members with the fiber concrete designed to carry the full shear capacity. This paper reports the results of a testing program on ultrahigh-performance steel fiber-reinforced concrete beams. Eight prestressed concrete beams were tested in shear with the test variables being the shear span-to-depth ratio and the quantity and type of steel fibers. The results of the tests, together with additional tests reported in the literature, are compared to the values derived from the plastic shear variable engagement predictive model for the determination of shear strength of steel fiber-reinforced concrete beams. A good correlation is observed with a mean model to experimental strength ratio of 0.92 and coefficient of variation of 0.12.

This article presents an overview of the material characteristics of a Malaysia blend of ultra-high performance ‘ductile’ concrete (UHPdC). Examples of the environmental impact calculations of UHPdC structures compared to that of conventional reinforced concrete (RC) design are presented. The comparison studies show that many structures constructed from UHPdC are generally more environmentally sustainable than built of the conventional RC with respect to the reduction of CO2 emissions, embodied energy and global warming potential. The enhanced durability of UHPdC also provides for significant improvements in the design life, further supporting the concept of sustainable development.

This paper presents the current state of practice in the development of ultrahigh-performance concrete (UHPC) bridge construction in Malaysia. Since 2006, Dura Technology (DT) has pioneered research in the optimal uses of UHPC in bridge construction through its Sustainable Bridge Construction Initiative. After several years of research and development work, DT has collaborated with the Malaysia Works Ministry to design and build bridges in some of their bridge projects, especially those bridges under the rural development program where sourcing of material, site access, and construction method are major challenges when using conventional methods. The most current information and details on the completed and ongoing UHPC bridge projects in Malaysia are presented. To date, a total of 26 segmental UHPC bridge projects have been constructed and opened for service. In this paper, a selected UHPC bridge case study is examined in terms of the design aspects, quality control, constructability, and of how ...

Deep beams are commonly used in tall buildings, offshore structures, and foundations. According to many codes and standards, strut-and-tie model (STM) is recommended as a rational approach for deep beam analyses. This research focuses on the STM recommended by ACI 318-11 and AASHTO LRFD and uses experimental results to modify the strut effectiveness factor in STM for reinforced concrete (RC) deep beams. This study aims to refine STM through the strut effectiveness factor and increase result accuracy. Six RC deep beams with different shear span to effective-depth ratios (a/d) of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00 were experimentally tested under a four-point bending set-up. The ultimate shear strength of deep beams obtained from non-linear finite element modeling and STM recommended by ACI 318-11 as well as AASHTO LRFD (2012) were compared with the experimental results. An empirical equation was proposed to modify the principal tensile strain value in the bottle-shaped strut of deep beams. The equation of the strut effectiveness factor from AASHTTO LRFD was then modified through the aforementioned empirical equation. An investigation on the failure mode and crack propagation in RC deep beams subjected to load was also conducted.

Experimental results from tests on seven 650 mm deep large-scale reactive powder concrete (RPC) I-section girders failing in shear are reported herein. The girders were cast using 150 170 MPa steel fiber RPC and were designed to assess the capacity to carry shear stresses in thin webbed prestressed beams without shear reinforcement. The tests showed that the quantity and types of fibers in the concrete mix did not significantly affect the initial shear cracking load but increasing the volume of fibers increased the failure load. A design model is developed to calculate the strength of the RPC beams tested in this study. The model is based on crack sliding and uses plasticity theory combined with observations from the variable engagement model for mode I failure of fiber reinforced concrete. The results of the model are compared with test data and show a good correlation.

Under normal circumstances, reinforced concrete structures (RCS) show excellent performance in terms of durability and structural behaviour except for the zones that are subjected to severe mechanical or cyclic loading and aggressive environmental conditions. Therefore the methods of rehabilitation or strengthening of these zones should be reliable, effective and economical. Today, many scientists, academics and engineers understood the extremely low porosity and low permeability characteristics of ultra high performance fibre concrete (UHPFC) giving its enhanced durability over high performance concrete (HPC), thus making it potentially suitable for rehabilitation and retrofitting problematic RCS. The advantages of utilising the technology of UHPFC in repairing works includes (i) decrease the working time needed for the rehabilitation works; and (ii) increase the serviceability and durability to an extent where the repaired structures can meet the expected design life of the structures, with minor preventative measure. This paper discusses and reviewing some of the most recent issues and findings using UHPFC as a repair material. The results of the findings will also be presented to prove that the UHPFC displays excellent repair and retrofit potentials in compressive and flexure strengthening and possesses high bonding strength and bond durability as compared with other types concrete. Abstract Under normal circumstances, reinforced concrete structures (RCS) show excellent performance in terms of durability and structural behaviour except for the zones that are subjected to severe mechanical or cyclic loading and aggressive environmental conditions. Therefore the methods of rehabilitation or strengthening of these zones should be reliable, effective and economical. Today, many scientists, academics and engineers understood the extremely low porosity and low permeability characteristics of ultra high performance fibre concrete (UHPFC) giving its enhanced durability over high performance concrete (HPC), thus making it potentially suitable for rehabilitation and retrofitting problematic RCS. The advantages of utilising the technology of UHPFC in repairing works includes (i) decrease the working time needed for the rehabilitation works; and (ii) increase the serviceability and durability to an extent where the repaired structures can meet the expected design life of the structures, with minor preventative measure. This paper discusses and reviewing some of the most recent issues and findings using UHPFC as a repair material. The results of the findings will also be presented to prove that the UHPFC displays excellent repair and retrofit potentials in compressive and flexure strengthening and possesses high bonding strength and bond durability as compared with other types concrete.

One of the significant breakthroughs in concrete technology in the 20th century was the development of ultra high performance fiber reinforced concrete (UHP-FRC) or reactive powder concrete (RPC) more commonly known as ultra high performance ‘ductile’ concrete (UHPdC) with compressive strength over 150 MPa and flexural strength over 30 MPa; and enhanced durability compared to conventional concrete. In brief, UHPdC is a cementitious based composite material that consists of the distinctive characteristics of the ultra-high performance concrete and high tensile strength steel fibers. UHPdC is a sustainable construction material with considerable amount of durability, ductility and tensile capacity which is mostly appropriate for use in the fabrication of precast members in civil engineering, structural and architectural applications. This paper presents a review on the UHPdC technology including an overview of material characteristics of a Malaysian UHPdC blend (i.e. Dura®), the principles of UHPdC development, its mix design, its advantages, and its applications.

This paper presents an overview on the use of high performance cementitious products and in using cement replacement materials, such as geopolymers in the development of sustainable design and construction. The design approach not only accounts for the limit states design, it also takes into consideration the environmental impact and durability of the designed structure. Two examples of environmental impact calculations, a bridge structure and a retaining wall, are provided for conventional Portland cement concrete, geopolymer concrete and reactive powder concrete solutions. The comparison studies show that many structures constructed of reactive powder concrete and of geopolymer concrete can provide for environmentally sustainable alternatives to the use of conventional concrete construction with respect to the reduction of CO2 emissions, embodied energy and global warming potential. The enhanced durability of reactive powder concrete and geopolymer concrete also provides for significant improvements in the design life, further ­supporting the concept of sustainable development.

This paper describes how a finite element model (FEM) is developed for the analysis of fiber reinforced concrete plane stress members that failed by the mode I fracture. The constitutive law is built on the variable engagement model where the behavior of a fiber composite is obtained by integration of its parts (fibers and concrete matrix) over the cracked surface. In developing the model in this way the formulation is made generally applicable to any type of steel fiber-cement based matrix and to fiber cocktails with any combination of fibers in the mix in any ratios. The model is demonstrated for a reactive powder concrete girder failing in shear using local and non-local modeling. The paper describes how the finite element formulation is shown to be capable of modeling the girder, with good accuracy observed for the global load versus displacement history and is shown to correctly capture the localized shear failure mechanism.