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International Concrete Abstracts Portal

Showing 1-5 of 1046 Abstracts search results

Document: 

SP-356_21

Date: 

October 1, 2022

Author(s):

Imad Eldin Khalafalla and Khaled Sennah

Publication:

Symposium Papers

Volume:

356

Abstract:

This paper investigates the use of glass fiber reinforced polymer (GFRP) bars to reinforce the jointed precast bridge deck slabs built integrally with steel I-girders. In addition to a cast-in-place slab, three full-size, GFRPreinforced, precast concrete slabs were erected to perform static and fatigue tests under a truck wheel load. Each slab had 200 mm (7.9 in) thickness, 2500 mm (98.4 in) width normal to traffic, and 3500 mm (137.8 in) length in the direction of traffic and was supported over a braced twin-steel girder system. The closure strip between connected precast slabs has a width of 125 mm (4.9 in) with a vertical shear key, filled with ultra-high-performance concrete (UHPC). Sand-coated GFRP bars in the precast slab project into the closure strip with a headed end to provide a 100 mm (3.9 in) embedment length. A static test and two fatigue tests were performed, namely: (i) accelerated variable amplitude cyclic loading and (ii) constant amplitude cyclic loading, followed by static loading to collapse. Test results demonstrated excellent fatigue performance of the developed closure strip details, with the ultimate load-carrying capacity of the slab far greater than the demand. While the failure in the cast-in-place slab was purely punching shear, the failure mode in the jointed precast slabs was punching shear failure with incomplete cone-shape peroration through the UHPC closure strip, combined with a major transverse flexural crack in the UHPC strip. This may be attributed to the fact that the UHPC joint diverted the load distribution pattern towards a flexural mode in the UHPC strip itself close to failure.


Document: 

SP-356_19

Date: 

October 1, 2022

Author(s):

Maha Hussein Abdallah, Hamzeh Hajiloo, and Abass Braimah

Publication:

Symposium Papers

Volume:

356

Abstract:

Several studies have shown the superiority of concrete-filled FRP tubes (CFFTs) over conventional reinforced concrete columns. These observations indicated that CFFT columns exhibit much better static structural performance (in terms of ductility and load-carrying capacity). However, up to date, very few studies have considered the behavior of CFFT columns under dynamic impact loading. This paper presents a numerical study to investigate the impact resistance of columns strengthened with glass FRP tubes. LS-DYNA finite element software is used to investigate CFFT and RC columns subject to lateral impact loading induced by a 221 kg pendulum. The columns are 1800 mm with the fixed support at the base and 152 mm internal diameter. The models are designed to simulate the destructive effects of a vehicle collision into bridge piers. The impact forces and deformation states are analyzed. The impact behavior of CFFT columns is also compared with the conventional RC columns counterparts. The numerical results showed that the CFFT columns had higher dynamic impact load and less lateral deflection compared with the RC counterparts. The impact resistance of the CFFT columns was enhanced with an increase in the FRP tube thickness.


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_01

Date: 

October 1, 2022

Author(s):

Ali F. Al-Khafaji, John J. Myers, and Hayder H. Alghazali

Publication:

Symposium Papers

Volume:

356

Abstract:

This paper presents an investigation of the bond performance of corrosion-free sand-coated glass fiber reinforced polymer bars (GFRP) implanted in two types of fly ash-based eco-friendly concrete. Steel reinforcement is prone to corrosion and is expensive to fix, therefore finding an effective alternative has become a must. One of these alternatives is GFRP bar. On the other hand, conventional concrete (CC) is not issueless, as it significantly affects the environment through its high-intensity CO2 emissions. Thus, other alternatives have been looked into to mitigate the CO2 problems. One of these alternatives is partially substituting Portland cement with another CO2 emission-free material such as fly ash. In this study, two levels (50% and 70%) of high-volume fly ash concrete (HVFAC) were used to investigate their bond performance with GFRP bars. Cylindrical specimens were tested under the effect of pullout load. Furthermore, the bars were investigated chemically and microstructurally to see if the fly ash had some influence on the GFRP bar. For concrete, performance rank analysis was carried out to identify the best concrete mixture in terms of slump, unit weight, cost, and bond strength. In addition, to verify the experimental work, two-dimensional finite element models were built using translator elements to present the bond action between the concrete and its reinforcement. The results of the investigation showed that the bond strength of GFRP bars was less than that of mild steel owing to GFRP bar deformation. In addition, CC resulted in a higher bond strength than HVFAC. The bar analyses did not yield any obvious signs of microstructural deterioration or chemical attack.


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.


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