Prestress Losses in Concrete Rafters with Openings

Authors

  • F. J. Alkhafaji Department of Civil Engineering, University of Baghdad, Iraq
  • A. F. Izzet Department of Civil Engineering, University of Baghdad, Iraq

Abstract

In this paper, experimental work was conducted to evaluate the losses in prestressing force of 13 (12 perforated and 1 solid) simply supported prestressed concrete rafters. All beams had the same dimensions and reinforcements. The tested beams were divided into four main groups and three additional subgroups were driven. These groups were classified according to size, number, and configuration of the openings, and the orientation of the posts (vertical or inclined). Regarding the prestress losses that have been affected by the cross-section properties, the provision of the codes is applicable only to prismatic solid beams, so non-prismatic or moreover perforated beams also need to be studied. This paper aims to propose a method based on the same code provisions but taking into consideration the cross-section variation along the beam length. The proposed method divides the overall length of the rafter into a number of assumed prismatic segments with heights measured at centers. Then, the overall prestress loss is found as the sum of these segments weighed by the ratios of the length of each beam segment to the overall length. The experimental results of the proposed method ranged from 84.749% to 95.607% denoting its validity.

Keywords:

prestress losses, rafter beams, openings

Downloads

Download data is not yet available.

References

A. E. Naaman, “Computation of prestress losses”, in: Prestressed Concrete Analysis and Design, Techno Press 3000, pp. 445–514, 2004

S. A. Youakim, A. Ghali, S. E. Hida, V. M. Karbhari, “Prediction of long-term prestress losses”, PCI Journal, Vol. 52, No. 2, pp. 116-130, 2007 DOI: https://doi.org/10.15554/pcij.03012007.116.130

A. Shokoohfar, A. Rahai, “Prediction model of long-term prestress loss interaction for prestressed concrete containment vessels”, Archives of Civil and Mechanical Engineering, Vol. 17, No. 1, pp. 132-144, 2017 DOI: https://doi.org/10.1016/j.acme.2016.09.002

E. G. Nawy, “Partial loss of prestress”, in: Prestressed Concrete: A Fundamental Approach, Prentice Hall, 5th Edition, pp. 73–105, 2009

D. M. H. Al-Fendawy, Strengthening of reinforced concrete t-beams using external post-tensioning, MSc Thesis, University of Baghdad, 2014

M. A. Mansur, K. H. Tan, Concrete beams with openings: analysis and design, CRC Press, 1999

N. K. Oukaili, A. Shammari, “Response of reinforced concrete beams with multiple web openings to static load”, Fourth Asia-Pacific Conference on FRP in Structures, Melbourne, Australia, December 11-13, 2013

V. N. Baykov, E. E Seagal, Reinforced concrete structures, Stroyizdat, 1991

M. A. J. Hassan, A. F. Izzet, “Serviceability of reinforced concrete gable roof beams with openings under static loads”, Engineering, Technology & Applied Science Research, Vol. 9, No. 5, pp. 4813-4817, 2019 DOI: https://doi.org/10.48084/etasr.3110

M. A. J. Hassan, A. F. Izzet, “Experimental and numerical comparison of reinforced concrete gable roof beams with openings of different configurations”, Engineering, Technology & Applied Science Research, Vol. 9, No. 5, pp. 5066-5073, 2019 DOI: https://doi.org/10.48084/etasr.3188

B. Aykac, S. Aykac, I. Kalkan, B. Dundar, H. Can, “Flexural behavior and strength of reinforced concrete beams with multiple transverse openings”, ACI Structural Journal, Vol. 111, No. 2, pp. 267-278, 2014 DOI: https://doi.org/10.14359/51686442

P. S. Samir, Precast/prestressed concrete Truss-Girder for roof applications, MSc Thesis, University of Nebraska-Lincoln, 2013 DOI: https://doi.org/10.1155/2014/524156

B. M. Dawood, H. A. Al-Katib, “Flexural strength of prestressed concrete beams with openings and strengthened with CFRP sheets”, International Journal of Scientific & Technology Research, Vol. 4, No. 6, pp. 161-172, 2015.

M. M. Mohammed, Strength, cracking and deformability of partially prestressed concrete beams under repeated loading, PhD Thesis, University of Baghdad, 2018

ACI-318, Building code requirements for structural concrete (ACI 318M-2014) and commentary, American Concrete Institute, Farmington Hills

P. Zia, H. Kent Preston, N. L. Scott, E. B. Workman, “Estimating prestress losses”, Concrete International, Vol. 1, No. 6, pp. 32-38, 1975

Downloads

How to Cite

[1]
F. J. Alkhafaji and A. F. Izzet, “Prestress Losses in Concrete Rafters with Openings”, Eng. Technol. Appl. Sci. Res., vol. 10, no. 2, pp. 5512–5519, Apr. 2020.

Metrics

Abstract Views: 318
PDF Downloads: 194

Metrics Information
Bookmark and Share

Most read articles by the same author(s)