الفهرس 
2.2Ultra High Strength Concrete DefinitionsOnly 14 pages are availabe for public view
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Abstract
Opening in modern concrete structures is to be used as access for utility ducts and pipes used for electricity, sanitation, heating ventilation, air conditioning, telephone and computer network and other mechanical services. Passing ducts through web opening in the beam instead of placing them underneath the beam soffit, maintain the floor height without change, as well as minimize the construction cost. Introducing of such openings significantly affects the structural behavior of reinforced concrete beams.
Thus, the main objective of this thesis to investigate the structural behavior of simply supported Ultra High-Performance Concrete (UHPC) beams with and without openings subjected to four-point bending test is an attempt to develop some recommendations for the design of UHPC beams provided with openings.
An experimental program is conducted, including eleven simply supported (UHPC) beams. Two beams without web openings were kept as control specimens, while the other nine beams contain openings. Different parameters were taken into consideration during this study; presence of opening at shear zone, percentage of steel fibers, web opening location, opening shape (rectangular or square), reinforcement schemes around the web openings (additional reinforcement or stirrups), shape of opening, number of opening and vertical eccentricity of opening at flexure zone.
Nonlinear finite element analysis (ANSYS 14.5) is used to develop the models and simulate the behavior of the tested UHPC beams. The experimental results were compared and validated by those obtained from the numerical analysis. An additional parametric study is performed by finite element analysis program to include cases that were not experimentally investigated. For this aim, thirty-seven models were analyzed and studied. The additional variables were: opening height,
opening length, opening location, main reinforcement ratio, stirrups reinforcement ratio, ratio of top and bottom reinforcement around the opening, compressive strength and the vertical eccentricity for opening from the beam axis.
Test results demonstrated that presence of openings in shear area of UHPC beam has a severe influence on the strength and serviceability of the beam. The inclusion of steel fiber for UHPC beam showed a remarkable effect on the overall structural behavior of the beams. The tested beams with steel fibers behaved stiffer and were also more ductile than the same type of beams without fibers. Using longitudinal rebars parallel to web openings perimeter as shear reinforcement schemes led to an enhancement in ultimate shear strength, stiffness, and toughness. It was revealed that finite element analysis is in good agreement with the experimental data with variation in various parameters. Finally, based on the obtained results, a general prediction equation was proposed to compute the failure loads of UHPC beams with openings.