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International Concrete Abstracts Portal

Showing 1-5 of 2473 Abstracts search results

Document: 

SP-356_11

Date: 

October 1, 2022

Author(s):

Ahmed G. Bediwy and Ehab F. El-Salakawy

Publication:

Symposium Papers

Volume:

356

Abstract:

Deep beams are common elements in concrete structures such as bridges, water tanks, and parking garages, which are usually exposed to harsh environments. To mitigate corrosion-induced damage in these structures, steel reinforcement is replaced by fiber-reinforced polymers (FRPs). Several attempts have been made during the last decade to introduce empirical models to estimate the shear strength of FRP-reinforced concrete (RC) deep beams. In this study, the applicability of these models to predict the capacity of simply supported deep beams with and without web reinforcement was assessed. Test results of 54 FRP-RC, 24 steel-fiber-reinforced concrete (FRC), and 7 FRP-FRC deep beams were used to evaluate the available models. In addition, a proposed model to predict the shear strength of FRPFRC deep beams was introduced. The model was calibrated against experiments conducted previously by the authors on FRP-FRC deep beams under gravity load. The model could predict the ultimate capacity with a mean experimental-to-predicted value of 1.04 and a standard deviation of 0.14.


Document: 

SP-356

Date: 

October 1, 2022

Author(s):

ACI Committee 440

Publication:

Symposium Papers

Volume:

356

Abstract:

Fiber-reinforced polymer (FRP) reinforcements for concrete structures and civil engineering applications have become one of the innovative and fast-growing technologies to stop the rapid degradation of conventional steel-reinforced concrete infrastructure. FRP reinforcements for construction can be divided into three main types: 1. External sheets or plates to rehabilitate and repair existing concrete and masonry structures, and in some cases steel and wood structures; 2. Internal FRP bars or tendons for new and existing reinforced concrete structures, and 3. FRP stay-in-place forms to be filled with unreinforced or reinforced concrete. A considerable and valuable development and application’s work has been accomplished during the last three decades, leading to the development of numerous design guidelines and codes around the world, making the FRP-reinforcement technology one of the fast-growing markets in the construction industry. During the ACI Concrete Convention, Fall 2021, four full sessions were sponsored and organized by ACI Committee 440. Session S1 was focused on the bond and durability of internal FRP bars; Session S2 on codes, design examples, and applications of FRP internal reinforcements; Session S3 on external FRP reinforcements; and Session S4 on new systems and applications of FRP reinforcements, such as CFFT post-tensioned beams, GFRP-reinforced concrete sandwich panels, FRP-reinforced masonry walls, CFFT under impact lateral loading, near-surface mounted FRP-bars, and GFRP-reinforced-UHPC bridge deck joints.


Document: 

SP-356_17

Date: 

October 1, 2022

Author(s):

Akram Jawdhari and Amir Fam

Publication:

Symposium Papers

Volume:

356

Abstract:

Recently, a new generation of concrete sandwich panels (CSPs) comprising ultra-high performance concrete (UHPC) wythes and glass fiber reinforced polymer (GFRP) as reinforcement and shear connectors was developed and evaluated experimentally. In this study, a non-linear finite element model is presented to study the detailed behavior of these panels under bending. The model included detailed features such as a constitutive material law that considers the post-crack stiffening of UHPC, failure of GFRP material, wythe-to-insulation contact and slipping, and stability failure. Compared with eight previously tested panels, the model predictions of ultimate load, general load-deflection behavior, and failure modes matched those from experiments. The composite degree of each panel, a key design parameter frequently used in characterizing the structural and thermal efficiencies of CSPs, was determined from the ultimate load of the tested panel and that of two additional numerically-based non and fully composite ones and ranged between 3 to 34%. The structural performance of the GFRP connector was deemed satisfactory for the range of composite degrees proposed for the panels. The validated model will be deployed in a large parametric analysis studying different material and geometric variables and assisting in developing a design tool to estimate the strength and composite degree of UHPC CSPs with GFRP reinforcement.


Document: 

SP-356_12

Date: 

October 1, 2022

Author(s):

Gianni Blasi, Daniele Perrone, and Maria Antonietta Aiello

Publication:

Symposium Papers

Volume:

356

Abstract:

The damage to infill walls caused by earthquakes often represents a major safety issue in reinforced concrete buildings. For this reason, masonry infill retrofit is increasingly adopted in high seismic hazard countries to increase the in-plane capacity of the walls and to avoid out-of-plane failure modes. On the other hand, the infill strengthening might significantly modify the seismic performance of the buildings, influencing the failure modes and the global ductility. Recent studies assessed that the enhancement of the in-plane strength of the infill can cause brittle failure in lightly shear reinforced columns. In this study, non-linear analyses are performed on reinforced concrete framed buildings to investigate the influence of the infill strengthening and column shear reinforcement on seismic performance. A three-dimensional numerical model is developed to assess the seismic capacity and the failure modes depending on the frame’s and infill’s details. The proposed study aims to encourage a smart design of the infill retrofit, geared toward a global performance enhancement rather than the mere strengthening of the single infill wall.


Document: 

SP-356_18

Date: 

October 1, 2022

Author(s):

Nancy Torres, J. Gustavo Tumialan, Antonio Nanni, Richard M. Bennet, and Francisco J. De Caso Basalo

Publication:

Symposium Papers

Volume:

356

Abstract:

This article presents a protocol for the flexural design of masonry walls reinforced with FRP bars. The proposed design methodology is based on the results of a research program on masonry walls reinforced with FRP bars subjected to out-of-plane (flexural) loads. The research program included testing full-scale masonry walls with different thicknesses, widths, and amounts and types of FRP reinforcement. The research program also included testing of full-scale masonry wall specimens to evaluate the effect of i) different bar lap splice lengths, ii) FRP bar diameter; iii) position of the FRP; iv) masonry strength and v) masonry material. Forty-seven masonry walls, 2.19 m high, were subjected to out-of-plane loads, and tested under quasi-static loading cycles. The test specimens included walls constructed using concrete and clay masonry units, reinforced with glass FRP (GFRP) in different configurations. All the FRP-reinforced masonry walls showed a bilinear moment-deflection curve with one steep slope up to the cracking of masonry and a decrease in stiffness after cracking. After failure occurred and as the out-of-plane load was progressively removed, the walls returned to a position close to the initial vertical position. The flexural design approach for FRP-reinforced walls provided good agreement with the experimental results.


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