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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 5 Abstracts search results
Document:
17-242
Date:
November 1, 2018
Author(s):
Lisa R. Feldman, Umesh Poudyal, and John Cairns
Publication:
Structural Journal
Volume:
115
Issue:
6
Abstract:
ACI 562-16 permits development and splice lengths of plain reinforcing bars to be assessed using code provisions that were in effect at the time of construction. However, previous research has shown that margins of safety provided by these provisions varied markedly between successive code editions and were unsafe for certain scenarios. A reliability-based equation, calibrated for safety in accordance with U.S. practice, is therefore developed from a test database of 29 viable splice specimens and 268 beam-end specimens. The subsequent comparison of results provided for plain bars using the proposed equation and those included in ACI 318-14 for deformed bars suggest that the historical rule-of-thumb that bottom-cast plain round bars require twice the development length of deformed bars is likely slightly conservative, while the considerable top-cast effect for plain bars results in their development length being almost three times that required for deformed bars.
DOI:
10.14359/51702230
17-047
January 1, 2018
Guruprasad Y. K., Ananth Ramaswamy, and K. Sajeev
Materials Journal
1
Identification and selection of the type of rock used as coarse aggregate in concrete exposed to high temperature is important from a standpoint of strength and safety of existing concrete structures. The present work documents the microscale behavior of granite coarse aggregates and its influence on strength parameters of concrete, exposed to different temperatures ranging from 425 to 850°C (797 to 1562°F) for an exposure time of 2 to 4 hours. Factors leading to decomposition of coarse aggregates in concrete under thermal loads were obtained using petrographical scannign electron microscopy (SEM) and electron probe micro analysis (EPMA) techniques. At temperatures ranging from 425 to 550°C (797 to 1022°F), the damage in concrete is gradual and is attributable to mortar shrinkage and separation of mortar-aggregate interface. Thermodynamic modeling results have shown that, beyond the formation temperature (715°C [1319°F]), minerals in the rock start to melt and migrate along the fracture planes, causing sudden reduction in load-carrying capacity in concrete.
10.14359/51701004
16-043
March 1, 2017
Lisa R. Feldman and John Cairns
114
2
ACI 562-13 permits development and lap splice lengths of historical reinforcing bar types to be assessed using code provisions that were in effect at the time of construction. A comparison of lap splice lengths for plain bars as predicted using provisions included in historical ACI code editions was therefore made to test results from 25 lap splice specimens and 220 beam-end specimens reinforced with round or square bars cast in the top or bottom position. A factor of safety of 2 was assumed for provisions based on a working stress design (WSD) approach. Provisions in all code editions reviewed do not appear to provide adequate safety for bars cast in the top position, while most appear reasonable for round bars cast in the bottom position. The analysis is also discussed in the context of possible construction scenarios that may be encountered when evaluating or rehabilitating existing reinforced concrete structures.
10.14359/51689163
D109-S04
July 1, 2012
Andor Windisch
109
4
Disc. 108-S49/From the September-October 2011 ACI Structural Journal, p. 523. Punching Shear in Post-Tensioned Flat Slabs with Stud Rail Shear Reinforcement. (Paper by Alessandra L. Carvalho, Guilherme S. Melo, Ronaldo B. Gomes, and Paul E. Regan). Discussion by Andor Windisch. Disc. 108-S51/From the September-October 2011 ACI Structural Journal, p. 542. Experimental Investigation of Reinforced Concrete Exterior Beam-Column Subassemblages for Progressive Collapse. (Paper by Sim Lim Yap and Bing Li). Discussion by Andor Windisch. Disc. 108-S53/From the September-October 2011 ACI Structural Journal, p. 562. Reinforcement-Free Decks Using Modified Strut-and-Tie Model. (Paper by Han Ug Bae, Michael G. Oliva, and Lawrence C. Bank). Discussion by Andor Windisch. Disc. 108-S55/From the September-October 2011 ACI Structural Journal, p. 581. Punching Shear of Thick Plates with and without Shear Reinforcement. (Paper by E. Rizk, H. Marzouk, and A. Hussein). Discussion by Andor Windisch. Disc. 108-S57/From the September-October 2011 ACI Structural Journal, p. 601. Ultra-High-Performance Concrete Bridge Deck Reinforced with High-Strength Steel. (Paper by Muhammad Azhar Saleem, Amir Mirmiran, Jun Xia, and Kevin Mackie). Discussion by Andor Windisch. Disc. 108-S59/From the September-October 2011 ACI Structural Journal, p. 620. Shear Behavior of Reinforced Concrete Beams with High-Strength Stirrups. (Paper by Jung-Yoon Lee, Im-Jun Choi, and Sang-Woo Kim). Discussion by Andor Windisch.
10.14359/51683877
100-S36
May 1, 2003
B. Sivarama Sarma, H. G. Sreenath, N. G. Bhagavan, A. Ramachandra Murthy, and V. Vimalanandam
100
3
Confined masonry panels in a building are considered to provide a better, cost-effective seismic-resistance structural system than unreinforced masonry panels. Ten different prototypes of confined masonry panels were tested for ductility under in-plane loads. The two types of variables considered in this study include hollow block masonry, brick masonry with a number of tie columns, and effect of opening. This study examines the variation of the ductility factors with respect to the arrangement of confined columns in both types of masonry panels. The experimental results showed that the confined columns in hollow block masonry shear wall improved the ductility and shear load characteristics. Based on the experimental results, regression curves were developed to compute the lateral deformations corresponding to the lateral shear resistance. The variation of maximum shear stress obtained from the experiments are also discussed with reference to the maximum permissible values as given in the BS 5628-1995 and ACI 530-95 codes of practice.
10.14359/12608
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