Structural Engineering
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- ItemIMPROVING CONCRETE PROPERTIES USING WASTE MATERIALS(An-Najah National University, 2023-10-08) Sabra, Raja K.Background: Fiber-reinforced concrete is a material of choice for enhancing the performance of concrete structure by improving their mechanical properties. Objectives: The study aims to understand the effects of adding waste fiber material, such as rivet mandrels and wire fibers, on the behavior of concrete and how it influences the workability, compressive strength, tensile strength, modulus of elasticity, and stress-strain relationship of concrete. Methodology: Experiments were conducted to observe the effects of adding fiber material on the workability, density, compressive strength, and tensile strength of concrete, while finite element analysis tested the effects of adding the same proportions of the previous material to the elastic modulus and stress-strain relationship of concrete. Results: The study shows that adding waste fibers generally enhances the mechanical properties of concrete up to a certain percentage, beyond which these benefits start to decline. Wires gave better results due to their higher aspect ratio compared to the revit mandrels. Conclusion: The study concludes that it is possible to enhance various mechanical properties of concrete by making use of waste fiber material and reduce the costs of producing traditional concrete.
- ItemIMPROVING DUCTILITY BEHAVIOR OF REINFORCED CONCRETE COUPLING BEAMS IN SPECIAL SHEAR WALLS USING ULTRA-HIGH-PERFORMANCE CONCRETE(An-Najah National University, 2024-12-31) Hlayel, AseelThe coupling beams are critical components that connect the shear walls of a coupled shear wall system. In the last few decades, the ductility of diagonal coupling beams has become one of the most important issues in seismic design. Design codes including the ACI 318 code, provide requirements for designing diagonal coupling beams to avoid failure with a reasonable level of ductility under seismic loads. However, the complex reinforcement detailing that is provided by the design codes causes a time-consuming construction process. This research aims to investigate the use of Ultra-High-Performance Concrete (UHPC) as a substitute for transverse reinforcement while maintaining the inclined bars in diagonal reinforced concrete coupling beams within coupled shear wall systems. The objective is to enhance ductility behavior and reduce construction time by simplifying reinforcement detailing. Numerical simulations using ABAQUS finite element software are performed and validated against published experimental data. Irregularly shaped buildings are selected for the analysis to accurately represent real-world conditions and achieve the study's objective. The main investigated parameters include the coupling beam aspect ratio, the depth of coupling beam and the length of the shear wall. The results show that UHPC-strengthened diagonal coupling beams in the coupled shear walls are capable of dispensing the complete amount of transverse reinforcement in diagonal coupling beams while achieving the required ductility level compared to traditional diagonal coupling beam designs specified by the code.
- ItemIMPROVING DUCTILITY BEHAVIOR OF REINFORCED CONCRETE COUPLING BEAMS IN SPECIAL SHEAR WALLS USING ULTRA-HIGH PERFORMANCE CONCRETE(An-Najah National University, 2024-12-31) Hlayel, AseelThe coupling beams are critical components that connect the shear walls of a coupled shear wall system. In the last few decades, the ductility of diagonal coupling beams has become one of the most important issues in seismic design. Design codes including the ACI 318 code, provide requirements for designing diagonal coupling beams to avoid failure with a reasonable level of ductility under seismic loads. However, the complex reinforcement detailing that is provided by the design codes causes a time-consuming construction process. This research aims to investigate the use of Ultra-High-Performance Concrete (UHPC) as a substitute for transverse reinforcement while maintaining the inclined bars in diagonal reinforced concrete coupling beams within coupled shear wall systems. The objective is to enhance ductility behavior and reduce construction time by simplifying reinforcement detailing. Numerical simulations using ABAQUS finite element software are performed and validated against published experimental data. Irregularly shaped buildings are selected for the analysis to accurately represent real-world conditions and achieve the study's objective. The main investigated parameters include the coupling beam aspect ratio, the depth of coupling beam and the length of the shear wall. The results show that UHPC-strengthened diagonal coupling beams in the coupled shear walls are capable of dispensing the complete amount of transverse reinforcement in diagonal coupling beams while achieving the required ductility level compared to traditional diagonal coupling beam designs specified by the code.
- ItemEXPLORING THE RELATIONSHIP BETWEEN THE DEFLECTION AMPLIFICATION FACTOR AND THE TIME PERIOD OF REINFORCMENT CONCRETE – MOMENT RESISTING FRAME STRUCTURES(An-Najah National University, 2024-06-12) Bsharat, MuradThe deflection amplification factor (Cd) is an important parameter in seismic design. Cd is essential in seismic design according to the American Society of Civil Engineers minimum design load standards (ASCE7-16) especially for the drift check and for the calculation of the seismic separator distance. Contractors face difficulty in implementing seismic separation, especially in high-rise buildings. The seismic separator is computed in ASCE7-16 depending on the Cd factor by calculating the inelastic displacement, which is crucial for calculating the seismic separation. Cd remains constant for the same structural system, as per ASCE7-16, regardless of the building characteristics such as (time period which depends on span length, story height and numbers of bays). The goal of this work is to obtain a Cd value for each building based on the building’s characteristics, which helps in reducing the width of the seismic separator, especially for high-rise buildings. To achieve this goal, various parameters associated with building characteristics that may influence Cd value were studied. 36 case studies of square-shaped building models with varying numbers of floors, floor height, span length, and the number of bays were analyzed using both linear and nonlinear time history analysis. Three-time history records that match the response spectrum in SAP2000 and seismomatch are used to compute Cd. On the other hand, the computer software, ETABS was used for the structural design considering both gravity and seismic loads. Results from the analysis show that ASCE 7-16 is conservative in presenting Cd values and that Cd varies depending on the characteristics of the building. The results show that the value of Cd decreases with increasing span length, story height, number of bays, and time period (Tn). The results of this study were used to develop an equation to estimate Cd based on the building characteristics. Keywords: Deflection amplification factor, Cd, SMRFs, Time history, Response Spectrum, nonlinear displacement, liner displacement, fiber hinge.
- ItemEFFECT OF SETBACK ON THE ELASTIC DYNAMIC RESPONSE OF REINFORCED CONCRETE FRAMED STRUCTURES(2023-01-03) Aseel Jamal Fareed BadranBackground: The collapse due to a seismic load typically starts at locations of the weakness of the structural system in the building. The weaknesses often occur due to a discontinuity in mass, strength, or stiffness between two adjacent floors. A well-known type of vertical geometric irregularity in structures is a setback, defined as a sudden decrease in the building's lateral dimension at a certain height. Problem Statement: The ASCE 7:16 code sets limitations on the Linear Equivalent Static method (LES), where it does not permit the use of this method for some types of irregularity, including setback irregularity, which are located in seismic design category (SDC) D, E and F. On the other hand, the LES method can be used in SDC B and C without restrictions. The code permits using the Modal Response Spectrum (MRS) and the Time History Analysis (THA) for all buildings without limitations on the SDC. Objectives: This study examines the effect of a setback on the elastic seismic response parameters of reinforced concrete framed structures, such as the fundamental period, the seismic base shear, the inter-story distribution of shear forces, and story drift. Finally, this study examines the solution to the problem of the code restrictions on the use of the LES method. Methodology: Buildings with Perimeter masonry walls with different setback ratios at different levels were analyzed using the commercial software ETABS 2016 according to the provisions of ACI318-14 and ASCE 7:16. The analysis was done using the LES method, MRS method, and THA method. The outcomes of the elastic response of the setback buildings were compared to similar buildings but without setbacks, in addition to comparing the results of the analysis methods used in this study. Conclusion: Based on the results, the vertical distribution of shear force from LES was modified depending on the THA method results. This modification allows the use of the LES method in various SDCs. Keywords: Linear Equivalent Static Analysis (LES); Modal Response Spectrum (MRS); Seismic Response; Setback structures; Time History Analysis (THA).