Coupling beams are structural elements used to connect two or more shear walls. The most common material used in the construction of coupling beam is reinforced concrete. The use of coupling beams along with shear walls require them to resist large shear forces, while possessing sufficient ductility to dissipate the energy produced due to the lateral loads. This study has been undertaken to produce a computational model to replicate the behavior of conventionally reinforced coupling beams subjected to cyclic loading. The model is developed in the finite element analysis software ABAQUS. The concrete damaged plasticity model was used to simulate the behavior of concrete. A calibration model using a cantilever beam was produced to generate key parameters in the model that are later adapted into modeling of two coupling beams with aspect ratios: 1.5 and 3.6. The geometrical, material, and loading values are adapted from experimental specimens reported in the literature, and the experimental results are then used to validate the computational models. The results like evolution of damage parameter and crack propagation from this study are intended to provide guidance on finite element modeling of conventionally reinforced concrete coupling beams under cyclic lateral loading.

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The dynamic behaviour of high-rise buildings has become a critical design consideration as buildings are built taller and more slender. Large wind vibrations cause an increase in the lateral wind loads, but more importantly, they can be perceived by building occupants creating levels of discomfort ranging from minor annoyance to severe motion sickness. The current techniques to address these issues include stiffening the lateral load resisting system, reducing the number of stories, or incorporating a vibration absorber at the top of the building. All of which have consequences on the overall project cost. The dynamic response of high-rise buildings is highly dependent on damping. Full-scale measurements of high-rise buildings have shown that the inherent damping decreases with height and recent in-situ measurements have shown that the majority of buildings over 250 meters have levels of damping less than 1% of critical. Studies have shown that small increases in the inherent damping can lead to vast improvement in dynamic response. A new damping system, the viscoelastic (VE) Fork Configuration Damper (FCD), has been developed at the University of Toronto to address these design challenges. The proposed FCDs are introduced in lieu of coupling beams in reinforced concrete (RC) coupled wall buildings and take advantage of the large shear deformations at these locations when the building is subjected to lateral loads. An experimental study was conducted on 5 small-scale VE dampers to characterize the VE material behaviour and 6 full-scale FCD samples in an RC coupled wall configuration (one designed for areas where low to moderate ductility is required and one with built-in ductile structural “fuse” for areas where high ductility is required). The VE material tests exhibited stable hysteretic behaviour under expected high-rise loading conditions and the full-scale tests validated the overall system performance based on the kinematic behaviour of coupled walls, wall anchorage and VE material behaviour. Analytical models were developed that capture the VE material behaviour and the FCD system performance well. An 85-storey high-rise building was studied analytically to validate the design approach and to highlight the improvements in building response resulting from the addition of FCDs.

The dynamic behaviour of high-rise buildings has become a critical design consideration as buildings are built taller and more slender. Large wind vibrations cause an increase in the lateral wind loads, but more importantly, they can be perceived by building occupants creating levels of discomfort ranging from minor annoyance to severe motion sickness. The current techniques to address these issues include stiffening the lateral load resisting system, reducing the number of stories, or incorporating a vibration absorber at the top of the building. All of which have consequences on the overall project cost. The dynamic response of high-rise buildings is highly dependent on damping. Full-scale measurements of high-rise buildings have shown that the inherent damping decreases with height and recent in-situ measurements have shown that the majority of buildings over 250 meters have levels of damping less than 1% of critical. Studies have shown that small increases in the inherent damping can lead to vast improvement in dynamic response. A new damping system, the viscoelastic (VE) Fork Configuration Damper (FCD), has been developed at the University of Toronto to address these design challenges. The proposed FCDs are introduced in lieu of coupling beams in reinforced concrete (RC) coupled wall buildings and take advantage of the large shear deformations at these locations when the building is subjected to lateral loads. An experimental study was conducted on 5 small-scale VE dampers to characterize the VE material behaviour and 6 full-scale FCD samples in an RC coupled wall configuration (one designed for areas where low to moderate ductility is required and one with built-in ductile structural “fuse” for areas where high ductility is required). The VE material tests exhibited stable hysteretic behaviour under expected high-rise loading conditions and the full-scale tests validated the overall system performance based on the kinematic behaviour of coupled walls, wall anchorage and VE material behaviour. Analytical models were developed that capture the VE material behaviour and the FCD system performance well. An 85-storey high-rise building was studied analytically to validate the design approach and to highlight the improvements in building response resulting from the addition of FCDs.

A key consideration in seismic design of buildings is to ensure that the lateral load resisting system has an appropriate combination of strength, stiffness and energy dissipation capacity. Hybrid coupled wall systems, in which steel beams are used to couple two or more reinforced concrete shear walls in series, can be designed to have these attributes and therefore have the potential to deliver good performance under severe seismic loading. This research presents an investigation of the seismic behavior of this type of structural system. System response of 12- and 18-story high prototypes is studied using transient finite element analyses that accounts for the most important aspects of material nonlinear behavior including concrete cracking, tension stiffening, and compressive behavior for both confined and unconfined concrete as well as steel yielding. The developed finite element models are calibrated using more detailed models developed in previous research and are validated through numerous comparisons with test results of reinforced concrete walls and wall-beam subassemblages. Suites of transient inelastic analyses are conducted to investigate pertinent parameters including hazard level, earthquake record scaling, dynamic base shear magnification, interstory drift, shear distortion, coupling beam plastic rotation, and wall rotation. Different performance measures are proposed to judge and compare the behavior of the various systems. The analyses show that, in general, hybrid coupled walls are particularly well suited for use in regions of high seismic risk. The results of the dynamic analyses are used to judge the validity of and to refine a previously proposed design method based on the capacity design concept and the assumption of behavior dominated by the first vibration mode. The adequacy of design based on the pushover analysis procedure as promoted in FEMA-356 (2000) is also investigated using the dynamic analysis results. Substantial discrepancies between both methods are observed, especially in the case of the 18-story system. A critical assessment of dynamic base shear magnification is also conducted, and a new method for estimating its effects is suggested. The method is based on a modal combination procedure that accounts for presence of a plastic hinge at the wall base. Finally, the validity of limitations in FEMA-368 (2000) on building height, particularly for hybrid coupled wall systems, is discussed.

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