Title:
Effects of Creating an Opening in Existing Beams
Author(s):
M. A. Mansur, Kiang-Hwee Tan, and Weng Wei
Publication:
Structural Journal
Volume:
96
Issue:
6
Appears on pages(s):
899-905
Keywords:
beams (supports); cracking (fracturing); deflection; openings; repair; shear strength; tests.
DOI:
10.14359/785
Date:
11/1/1999
Abstract:
Nine T-beams were fabricated with circular openings through the web to simulate drilling of holes in an existing beam either for the passage of service ducts or for the determination of in place concrete strength. The major parameters considered in the study were the size and location of openings. These beams were tested to failure. Test results indicate that an opening, when created near the support region of an existing beam, leads to early diagonal cracking and significantly reduces the strength and stiffness of the beam. Also, irrespective of the size and location of the opening, the serviceability limit state of cracking may be seriously affected. Filling the opening (created for the determination of in place concrete strength) by nonshrink grout is not adequate to restore the original response. Therefore, when such openings are unavoidable, adequate measures should be undertaken to strengthen the beam so as to retain the degree of safety and serviceability considered in the original design. It has been shown that the weakness introduced by creating an opening may be completely eliminated by employing a suitable strengthening method.