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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 10652 Abstracts search results
Document:
23-029
Date:
February 11, 2025
Author(s):
Hyunsu Kim, Yousun Yi, Ryan A. Boehm, Zachary D. Webb, Jongkwon Choi, Juan Murcia-Delso, Trevor D. Hrynyk, and Oguzhan Bayrak
Publication:
Structural Journal
Abstract:
This paper presents results obtained from an experimental study focused on the impacts of geometric design parameters on the structural performance of drilled shaft footings. Large-scale tests were conducted on specimens subjected to uniform column compression and constructed with different geometric conditions permitting the examination of varied strut inclination, shaft diameter, and footing depth. The experimental results obtained confirmed that footing strength was highly dependent on strut inclination while shaft diameter affected the ultimate damage pattern. Strength calculations based on 3D strut-and-tie modeling guidelines recently developed by the authors provided less conservative results than previous recommendations and resulted in levels of accuracy consistent with those of other shear design procedures adopted in code provisions.
DOI:
10.14359/51745637
23-106
Seyed Mohammad Hosseini, Salaheldin Mousa, Hamdy M. Mohamed, and Brahim Benmokrane
The geometry of arched (vertically curved) reinforced concrete (RC) members contributes to the development of additional stresses, affecting their flexural and shear strength. This aspect of curvilinear RC members reinforced with GFRP bars has not been reported in the literature. In addition, there are no specific design recommendations that consider the effect of curvilinearity on the flexural and shear strength of curved GFRP-RC members. This study has performed pioneering work in developing models to predict the flexural and shear strength of curvilinear GFRP-RC members with a focus on precast concrete tunnel lining segments. Eleven full-scale curvilinear GFRP-reinforced tunnel segment specimens were tested under bending load as the experimental database. Then, a model was developed for predicting the flexural strength of curvilinear GFRP-RC members. This was followed by the development of two shear-strength prediction models based on the modified compression field theory (MCFT) and critical shear crack theory (CSCT). After comparing the experimental and analytical results, a parametric study was performed to evaluate the effect of different parameters on the flexural and shear strength of curvilinear GFRP-reinforced members. The results indicate that neglecting the curvilinearity effect led to a 17% overestimation of the flexural capacity, while the proposed models could predict the flexural capacity of the specimens accurately. The proposed models based on the MCFT—referred to as the semi-simplified modified compression field theory (SSMFT) and the improved simplified modified compression field theory (ISMCFT)—predicted the shear capacity of the specimens with 28% conservatively. In addition, the modified critical shear crack theory (MCSCT) model was 10% conservative in predicting the shear capacity of curvilinear GFRP-RC members.
10.14359/51745638
23-117
Mustafa M. Raheem and Hayder A. Rasheed
Extensive experimental verification has shown that the use of fiber-reinforced polymer (FRP) anchors in combination with externally bonded fiber-reinforced polymer composites increases the flexural capacity of existing Reinforced Concrete (RC) structures. Thus, a rational prediction model is introduced in this study so that the fiber splay anchors may be accurately designed for practical strengthening applications. Simplified structural mechanics principles are used to build this model for capacity prediction of a group of fiber splay anchors used for FRP flexural strengthening. Three existing test series utilizing fiber splay anchors to secure FRP-strengthened T-beams, block-scale, and one-way slabs were used to calibrate and verify the accuracy and applicability of the present model. The present model is shown to yield very accurate predictions when compared to the results of the block-scale specimen and eight different one-way slabs. The proposed model is also compared with the predictions of a design equation adapted from the case of channel shear connectors in composite concrete-steel construction. Results show a very promising correlation.
10.14359/51745639
23-298
Seyed Arman Hosseini, Ahmed Sabry Farghaly, Abolfazl Eslami, and Brahim Benmokrane
This study addressed a critical knowledge gap by examining the influence of staggering on the bond strength of lapped glass fiber-reinforced polymer (GFRP) bars in concrete members. It involved a comprehensive investigation of new-generation GFRP bars with varying staggering configurations in nine large-scale GFRP-RC beams with a rectangular cross-section of 300 mm × 450 mm and a length of 5,200 mm. The tests investigated splice strength with three staggering distances: 0, 1.0, and 1.3 times the splice length (ls) from the center-to-center of two adjacent splices, and three splice lengths of 28, 38, and 45 times the bar diameter (db). Results revealed a slight improvement in ultimate load-carrying capacity (less than 10%) for partially and fully staggered splices compared to non-staggered ones, with the latter exhibiting a more ductile failure mode. The effect of staggering was consistent across different splice lengths, demonstrating that splice length was not a factor. Although staggering reduced flexural crack width, it increased the total number of cracks due to expanded splice regions. Bond strength improved with staggering, with gains of 4.0% and 8.0% for partially and fully staggered splices, respectively. ACI 440.11-22 provides more accurate predictions of the bond strength of lap-spliced GFRP bars than the other design codes showing an average test-to-prediction ratio of 1.03 for non-staggered splices. Nevertheless, it requires some reconsideration when it comes to staggered splices. To address this, a proposed modification factor was introduced to account for staggering conditions when calculating bond strength and splice length in ACI 440.11-22.
10.14359/51745640
23-304
Gray Mullins, Rajan Sen, David Ostrofsky, and Kwangsuk Suh
This study characterized pitting corrosion in prestressed piles, links it to stress concentration factors via ultimate strength tests, and finally incorporates the findings into a simple predictive damage assessment model. Six 1/3 scale Class V concrete prestressed piles were exposed for 38 months to outdoor tidal cycles simulating a marine environment. At exposure end, 24 strands were extracted from the piles, and the corrosion loss along the strands was quantified using a new Pascal’s law-based strand profiler. This identified regions of locally higher steel loss caused by pitting corrosion. The same data set was used to confirm gravimetric loss measurements by summing localized section losses over the specimen length. Profiler data was complemented by microscopic imaging to further define pitting geometry. Ultimate load tests were conducted to examine the effect of pitting on residual tensile strength and ductility. Similitude principles were used to show how the results can be used to predict the state of in-service pile strands where only inspection report crack widths are required.
10.14359/51745641
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