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Volume 4

International Conference on

CIVIL & STRUCTURAL ENGINEERING

June 21-22, 2018 Paris, France

Journal of Steel Structural and Construction

ISSN : 2472-0437

Civil Engineering 2018

June 21-22, 2018

Behavior of lightweight reinforced concrete beams with openings in shear zones

Mohamed Ahmed

Cairo University, Egypt

he construction of modern buildings requires many pipes and ducts to accommodate necessary services such as air conditioning,

electricity, telephone, and computer network. Passing the required service through web openings in these beams is more desirable

than passing it underneath the beams to keep of building aesthetics, also decrease the total height of building as well as decreases the

total construction cost. Many researches were prepared to investigate the effect of openings on strength and stiffness of the reinforced

concrete beams under different conditions to get suitable solutions to avoid or reduce these effects. Also, this research has been

prepared to study the effect of a rectangular opening on the behavior of simply-supported lightweight, mixed and normal reinforced

concrete beams with rectangular cross section using a nonlinear finite element program (ANSYS 17.2). For this purpose, a set of

fifty one beams were analyzed to study the behavior of beam with opening under different conditions. All tested beams were simply

supported beams with 4050 mm long, 3750 mm span, and cross section of (200 mm width and 500 mm total depth). Main parameters

were: opening length ( ), opening height ( ), position of the opening along the beam axis (X), type of concrete, ultimate compressive

strength ( ) and reinforcement arrangement around opening. The wide range for these parameters was taken as follows: W=(0.42 d,

0.65 d, 0.85 d and 1.30 d), where d is the beam effective depth; h=(0.28 d, 0.45 d, 0.56 d, and 0.67 d); X=(0.50 d, 0.75 d, 1.0 d, and

1.25 d); fcu = 21 MPa for Lightweight, 41 MPa for normal weight, and 26 MPa for mixed concrete. The reinforcement arrangement

around the opening at top and bottom chord As1= (0.64 As, 0.36 As, 0.12 As, and without RFT) where As is the main longitudinal

reinforcement of the beam. Spacing between main stirrups equal to 200 mm and spacing between stirrups around opening equal to

50 mm. Based on these conditions the study revealed that, provision of openings in lightweight reinforced concrete beams at shear

zone changes the behavior of beam. The ratio of reduction in ultimate load increased from 8% to 23%, when the ratio of opening

depth to beam effective depth (h⁄d) increased from (0.28 to 0.67). While it increased from 5% to 18%, when the opening length to

beam effective depth ratio (W⁄d) increased from 0.42 to 1.30. The effect of opening location becomes more significant when opening

is located close to support or at a distance equals to half beam depth. When the opening is located at a distance equal to half beam

depth, the cracking load and the ultimate load were reduced by 16%, and 13%, respectively. Also, when the opening is located at a

distance equals to beam depth, the cracking load and the ultimate loads were reduced by only 9%, and 7%, respectively. Increasing

the ultimate compressive strength from 21 to 41 MPa decreases deflection and increases cracking and ultimate loads by 36%, 33%,

and 37%, respectively. In addition to, increasing the reinforcement around the opening with certain arrangement helps to recover the

loss in ultimate load of beam with openings.

J Steel Struct Constr 2018, Volume 4

DOI: 10.4172/2472-0437-C1-007