Journal Jan 2021

Prefabricated fiber reinforced polymer composite stay-in-place structural formwork for bridge decks Anna Pridmore, Vistasp M. Karbhari

Bridge decks require substantial maintenance due to deterioration and degradation resulting from cyclic loading induced damage and environmental exposure. Cast-in-place construction also requires significant time and logistics. The use of appropriately designed fiber reinforced composite stay-in-place formwork has been shown to reduce construction time and to substantially eliminate the use of reinforcing steel in the deck. This paper reports on the use of these systems in box-girder bridge decks demonstrating enhanced structural performance in terms of deflection response, stiffness, and residual deformation using full-scale tests under quasi-static and cyclic loading.

Design approach for concrete beams prestressed with high-strength basalt fiber-reinforced polymer tendons Ali Alraie, Vasant Matsagar

Use of basalt fiber-reinforced polymer (BFRP) rebars has lately been introduced as an effective means for replacement of the conventional steel reinforcement in concrete structures owing to their relatively superior physical and mechanical properties. In the present study, BFRP-prestressed concrete (BFRP-PSC) beams have been designed, analyzed, and an assessment of the flexural behavior has been carried out from the experimental and numerical results. The beam was designed as a partially prestressed under-reinforced section with reinforcements distributed in two layers aiming to have a kind of progressive failure, imparting increased nonlinearity. The finite element (FE) analysis was carried out in the commercially available software ABAQUS® using the concrete damaged plasticity (CDP) approach for modeling the concrete, and the numerical results were found in a good agreement with the results obtained from the current design approach. The study introduced an effective design approach for the structural members prestressed using the BFRP tendons with improved ductility, and thereby provided a solution for the otherwise brittle failure of the under-reinforced BFRP-prestressed/ reinforced concrete structures.

Concrete slab replacement of expressway road bridge in Japan Toshihiko Nagatani

This paper describes the current state of maintenance and counter measures for expressways, which are an important infrastructure in Japan. The main measure taken in the long-term maintenance of expressway bridge structures is the replacement of damaged RC slabs. The decision to implement the slab replacement project was made based on an examination of the current status of RC slab maintenance of bridges which have been in service for some 50 years. Then, the concept of the renewal project and the method of implementing the renewal work are explained, and prospects and counter measures for future issues are described.

Experimental and analytical studies on concrete-filled triaxially-braided hybrid FRP structures under static loading Florian Jonas, Shubham Soni, Vasant Matsagar, Jan Knippers

Fiber-reinforced polymer (FRP) confined concrete composites are increasingly used in building construction and civil engineering for retrofitting, strengthening of concrete compression members, and structural systems in harsh environmental conditions. Whereas a vast number of investigations on the increase in the compression strength of concrete columns through confinement of wound tubes and wrapped FRPs exists, experimental investigations on braided and especially triaxially-braided hybrid FRP tubes for confinement in compression and reinforcement in bending are very limited and hence presented in this paper. The aim of this study is to experimentally investigate the confinement effect and strength increase through a multiaxial stress state in concrete, provided by triaxially-braided confinement hulls with glass (G) and carbon (C) fibers. Therefore, cylindrical test specimens with two different hull thicknesses were mechanically tested under static compression loads. The results of this experimentation help to evaluate the effectiveness of the C-G-FRP confinement hull as a confining material. Furthermore, commonly accepted existing analytical models for the stress-strain behavior of confined concrete, which were developed for non-braided FRP confinement hulls are applied, evaluated, and compared to the experimental results. To determine the material properties of the triaxially-braided C-G-FRP confinement hulls flat coupon tests and split-disk ring tests were conducted. The difference in strength is expressed by an introduced split-disk hoop rupture factor. Lastly, the use of the triaxially-braided C-G-FRP confinement hulls as reinforcement for concrete beams and the influence of the fiber angle are experimentally investigated through a four-point bending test with three different fiber angles.

Finite element studies on the flexure-shear behavior of steel and hybrid fiber reinforced prestressed concrete beams Chandrashekhar Lakavath, Murali Sagar Varma Sagi, Suhas S. Joshi, S. Suriya Prakash

The flexure-shear behavior of steel and hybrid fiber reinforced prestressed concrete beams are studied in three-dimensional nonlinear finite element analysis. Test results of a prestressed concrete beam were simulated using finite element software ABAQUS. The volume fraction of the steel fibers (SF) and hybrid (HB) fibers are the main variables considered in this study. The other parameters such as the cross-section area of concrete, longitudinal reinforcement ratio and shear span to depth ratio were kept constant. The concrete behavior was simulated through the concrete damage plasticity (CDP) model. The loading and boundary conditions in the FE models were kept similar to that of experimental testing. The load-deflection response, ductility, and failure modes of the beams were predicted well. During the experimentation, the crack initiation, crack propagation was traced by digital image correlation (DIC) technique. An increase in the volume fraction of fibers increased the flexure capacity and ductility. Around 109% and 89% improvement in ductility is observed at 1.0% volume fraction of steel and hybrid fibers, respectively.

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