New directions for reinforced concrete coastal structures

2016

The University of Miami deliberately chose to construct a pedestrian bridge using concrete elements solely reinforced and prestressed with fiber-reinforced polymer (FRP) composites to demonstrate its commitment to innovation and sustainability. In addition to showcasing concrete reinforcing bars made of basalt and glass FRP (BFRP and GFRP), the bridge features unique BFRP forms such as continuous close stirrups used in the pier-caps and curbs as well as prefabricated BFRP cages for the auger-cast piles. The main load-carrying members of the bridge are two prestressed concrete girders of double-tee shape (as used in parking garage structures) with shortened flange overhangs. Each girder stem was prestressed with nine carbon FRP (CFRP) strands. Elements of the bridge were instrumented with vibrating-wire gages to monitor performance over time and during two load tests conducted on one of the prestressed concrete girders at the precast yard and on the completed structure, respectively....

Advances in Civil Engineering Materials, 2019

To support and promote the deployment of innovative technologies in infrastructure, it is 6 fundamental to quantify their implications in terms of both economic and environmental impacts. 7 Glass Fiber-Reinforced Polymer (GFRP) bars and Carbon Fiber-Reinforced Polymer (CFRP) strands are validated corrosion-resistant solutions for Reinforced Concrete (RC) and Prestressed Concrete (PC) structures. Studies on the performances of FRP reinforcement in seawater and saltcontaminated concrete have been conducted and show that the technology is a viable solution. Nevertheless, the economic and environmental implications of FRP-RC/PC deployment have not been fully investigated. This paper deals with the Life Cycle Cost (LCC) and Life Cycle Assessment (LCA) analyses of an FRP-RC/PC bridge in Florida. The bridge is designed to be entirely reinforced with FRP bars and strands and does not include any Carbon Steel (CS) reinforcement. Furthermore, the deployment of seawater concrete in some of the elements of the bridge is considered. LCC and LCA analyses at the design stage are performed. Data regarding equipment, labor rates, consumables, fuel consumption and disposal were collected during the construction phase and the analysis is refined accordingly. The FRP-RC/PC bridge design is

Rilemweek, 2018

The number of Reinforced Concrete (RC) bridges needing repair or seismic retrofit is rapidly increasing in many western countries since the most were built between the 50s and the 70s, before modern bridge design codes were developed. After 50 years from their construction, they may have experienced a series of lower-than-design earthquakes, cause of limited structural damage, or they may have endured harsh environmental conditions, cause of possible corrosion in reinforcement bars. In lieu of the substitution of the entire structures, service life of existing RC bridges can be extended adopting reliable repair or retrofit methods able to restore structural safety and durability of materials. A case study of an existing RC bridge pier retrofitted with Ultra High Performance Fibre Reinforced Concrete (UHPFRC) is presented. A thin layer of UHPFRC cast around the bridge column (i.e. jacketing) with additional reinforcements can improve seismic response to the new design levels and increase protection of reinforcements against corrosion, thanks to the high durability of the new repair material. The results of a 1:4 scale laboratory test of the retrofitted bridge pier are finally presented to demonstrate the ability of the method to improve seismic response of existing structures.

2004

This paper compares and reviews the recommendations and contents of the guide for the design and construction of externally bonded FRP systems for strengthening concrete structures reported by ACI committee 440 and technical report of Externally bonded FRP reinforcement for RC structures (FIB 14) in application of carbon fiber reinforced polymer (CFRP) composites in strengthening of an aging reinforced concrete headstock. The paper also discusses the background, limitations, strengthening for flexure and shear, and other related issues in use of FRP for strengthening of a typical reinforced concrete headstock structure such as durability, de-bonding, strengthening limits, fire and environmental conditions. A case study of strengthening of a bridge headstock using FRP composites is presented as a worked example in order to illustrate and compare the differences between these two design guidelines when used in conjunction with the philosophy of the Austroads (1992) bridge design code.

Construction and Building Materials, 2010

The novel concept of this paper is to investigate the required recoverability of existing important reinforced concrete (RC) bridges retrofitted with fiber-reinforced polymers (FRP) to restore their original functions after a moderate or strong earthquake. Hence, this paper presents an up-to-date literature search on the inelastic performance of 109 FRP-retrofitted columns with lap-splice deficiency, flexural deficiency, or shear deficiency. The study is conducted in the following steps: using post-yield stiffness as a seismic index, the effectiveness of FRP jackets in enhancing the inelastic stage performance of non-ductile reinforced concrete columns is scrutinized for the available database; the performance of columns which successfully achieved post-yield stiffness is categorized in accordance with the required recoverability after an earthquake; and according to the definition of a controllable recoverable structure, the appropriate composite jacket thickness is calculated. In the view of a proposed mechanical model of an FRP-RC damage-controllable structure, 61 columns of the available database exhibited idealized lateral performance with stable post-yield stiffness, or secondary stiffness. Lateral drift at the end of the recoverable state is defined from the hysteretic responses of 39 columns and is visualized as a ratio of column lateral drift by the end of the post-yield stiffness with explicit consideration for the effect of both column cross-section shape and deficiency. Finally, suitable FRP design assumptions and concepts certifying the reality of post-yield stiffness are given. Furthermore, in the light of Seismic Design Specifications of Highway Bridges in Japan, a FRP strengthening design guideline that considers and evaluates structural recoverability is proposed.

Journal of Composites for Construction, 2007

Worldwide interest is being generated in the use of fiber-reinforced polymer composites ͑FRP͒ in the rehabilitation of aged or damaged reinforced concrete structures. As a replacement for the traditional steel plates or external posttensioning in strengthening applications, various types of FRP plates, with their high strength-to-weight ratio and good resistance to corrosion, represent a class of ideal material in externally retrofitting. This paper describes a solution proposed to strengthen the damaged reinforced concrete headstock of the Tenthill Creeks Bridge, Queensland, Australia, using FRP composites. A decision was made to consider strengthening the headstock using bonded carbon FRP laminates to increase the load carrying capacity of the headstock in shear and bending. The relevant guidelines and design recommendations were compared and adopted in accordance with AS 3600 and Austroads bridge design code to estimate the shear and flexural capacity of a rectangular cracked FRP reinforced concrete section.

2017

MATEC Web of Conferences

This paper presents Fibre Reinforced Polymer (FRP) as a third alternative construction material worth considering when retrofitting a bridge structure. FRP offers the following advantages: lighter than steel and concrete, non-corrosive, low in maintenance, stronger than structural steel and fatigue resistant. FRP has been used in Europe and more specifically in the Netherlands for almost 20 years in the retrofitting of road bridges, in new pedestrian bridges, road bridges and lock doors for sluices. The Netherlands has recently developed the updated Dutch Design Code CUR Recommendation 96, which was published in December 2017. The CUR Recommendation 96 will form the basis for developing the Eurocode FRP which is expected to be published between 2020 and 2025. The use of FRP in retrofitting of bridges is presented using examples which demonstrate how existing concrete decks, and steel and concrete substructures could be retained by the use of FRP in the retrofitting solution. Due to FRP being a relatively unknown material within the South African bridge design field, the authors have embarked on an awareness campaign targeting academics, government bodies, suppliers, manufacturers and contractors, with the aim of presenting FRP as a third alternative construction material in the South African bridge fraternity.

ICCRRR, 2018

The increasing number of road infrastructures needing repair and retrofit is raising the problem of how to improve seismic behaviour for all those structures for which substitution is unlikely. This work deals with the application of a retrofitting technique for Reinforced Concrete (RC) elements based on the use of Ultra High Performance Fibre Reinforced Concrete (UHPFRC). A thin layer of UHPFRC, cast around an existing RC element, can both improve its structural performance and enhance its durability against environmental actions. This kind of rehabilitation intervention may represent, in many practical cases, a cost effective solution compared with the replacement of the entire structure. The aim of this paper is the definition of a reinforcement strategy and the presentation of a 1:4 scale laboratory test of a highway bridge pier reinforced with a 30 mm layer of UHPFRC.

Fibers

In this review, we discuss the basic issues related to the use of FRP (fiber-reinforced polymer) composites in bridge construction. This modern material is presented in detail in terms of the possibility of application in engineering structures. A general historical outline of the use and development of modern structural materials, such as steel and concrete, is included to introduce composites as a novel material in engineering, and the most important features and advantages of polymers as a construction material are characterized. We also compare FRP to basic structural materials, such as steel and concrete, which enables estimation of the effectiveness of using of FRP polymers as structural material in different applications. The first bridges made of FRP composites are presented and analyzed in terms of applied technological solutions. Examples of structural solutions for deck slabs, girders and other deck elements made of FRP composites are discussed. Particular attention is pa...