Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 32 for “"stiffness degradation"”.
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Factors affecting the initial stiffness and stiffness degradation of cohesive soils
… role of the following factors on both initial stiffness and small strain (Ea<O.1%) non-linearity in undrained triaxial compression: consolidation stress level (0.5-12 ksc), overconsolidation ratio ( 1,2,4,8), pre-shear consolidation stress path (loading vs. unloading), pre-shear lateral stress …
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Effect of Hysteresis Type on Drift Capacity for Global Collapse of Moment Frame Structures for Seismic Loads
… lead to different levels of response because of degradation in strength and stiffness. To examine the existence and magnitude of this effect, this research aims to: (1) Determine the global collapse capacities of several classes of moment frame buildings under seismic loads. (2) Develop the basis …
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Monotonic and Cyclic Simulation of Screw-Fastened Connections for Cold-Formed Steel Framing
… that can simulate pinching and strength and stiffness degradation consistent with CFS screw-fastened connections. The user element is verified at the connection level, including complex cyclic deformation paths, by comparing to OpenSees connection simulation results. The connection model is …
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Evaluation of Connection Fracture and Hysteresis Type on the Seismic Response of Steel Buildings
… the design forces. Linear, bilinear, strength degradation, stiffness degradation, and connection fracture models were used to determine the effects of hysteresis type on multi-degree-of-freedom (MDOF) structural systems.
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Performance of RC Bridge Columns under Cyclic Combined Loading including Torsion
… of RC bridge columns with respect to strength, stiffness, deformation and progression of damage, and cause complex failure modes and in turn influence the overall behavior of the bridge system. This study performed experimental and analytical studies in order to investigate the performance of RC …
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Probabilistic capacity and seismic demand models and fragility estimates for reinforced concrete buildings based on three-dimensional analyses
… performance levels consider the strength and stiffness degradation under the bi-axial loading. The proposed approach for the fragility estimate considers the uncertainties involved in the spectral acceleration components and capacity variation. The proposed approach is illustrated considering …
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Detecting and Quantifying Damage in Buildings Using Earthquake Response Data and Capacity Curves
… response and capacity curves in terms of stiffness degradation and ductility ratios either at an inter-story or fundamental mode resolution. The method is calibrated by implementation on numerical simulations and experimental models and applied to the historical response data of the …
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Micromechanics-based approach to predict strength and stiffness of composite materials
… the durability of composites is the strength and stiffness degradation during service. Traditionally, these materials have been analyzed by methods which do not take into account variations in the material at the fiber/matrix level. In addition, manufacturing techniques have advanced enough so …
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Effects of Surface Condition on the Fatigue Behavior of CFRP-to-Steel Joints
… the nonlinear strength wearout Model (NLSW) and stiffness degradation were used. It was found that residual strength and stiffness decreased in a non-linear fashion. A non-linear model was used that agrees well with the experimental results and can be used to predict the residual strength of the …
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An experimental investigation of homogeneous fatigue damage in a random short-fiber composite under combined tension-torsion loading
… measured as the relative change in the elastic stiffness tensor of the composite. Multiaxial extensometry is developed for strain measurements, and an approximate analytical technique is evolved for online prediction of the multiaxial stress state in the damaged material. Measurements of …
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Fe Modeling In Support Of Vibration Based Damage Detection In Bridges
… of defining a relationship between substructure stiffness degradation and frequency and mode shape modulation induced by damage. The relationship is explored through finite element modeling of primarily an experimental representation of a three-span concrete bridge structure located at the …
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Active vibration control of civil engineering structures
… and the limitation of these devices under stiffness degradation when the structure enters the inelastic region. Linear Quadratic Gaussian and H-infinity active control schemes are designed, simulated and assessed for buildings, modelled as lumped parameter systems, including base and …
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Nonlinear Truss Analysis of Non-ductile Reinforced Concrete Frames with Unreinforced Masonry Infills
… is shown to adequately capture the strength and stiffness degradation and the damage patterns while entailing a reduced computational cost (compared to that of NLFEA). The proposed method is expected to bridge the gap between overly crude equivalent strut models and computationally expensive …
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A fabrication stress model for axisymmetric filament wound composite structures
… resin, material cure transition, and fiber stiffness degradation in a compressive strain state. Two case studies were selected to evaluate and to illustrate the use of the fabrication stress model: the space shuttle booster Joint overwrap and a filament wound composite bottle. The analysis …
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Elastic properties and failure behavior of disordered porous solids : a potential-of-mean-force-based lattice element approach
… in disorder can considerably deteriorate both stiffness and failure resistance of disordered porous solids. Specifically, it is shown that this disorder-induced strength and stiffness degradation results from a transition from a state governed by a single-pore stress concentration to a state …
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Fiber fracture in continuous-fiber reinforced composite materials during cyclic loading
… do not demonstrate any significant loss of stiffness during fatigue cycling compared to other lay-ups. Even if stiffness degradation was significant, due to the nature of damage in this material system it would be impossible, practically, to monitor that change using conventional techniques …
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Hysteresis modeling of wood joints and structural systems
… namely, (1) nonlinear, inelastic behavior, (2) stiffness degradation, (3) strength degradation, (4) pinching, and (5) memory. The constitutive law takes into account the experimentally observed dependence of wood joints' response to their past history (Le., the input and response at earlier …
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Concrete columns and beams reinforced with FRP bars and grids under monotonic and reversed cyclic loading
… flexure dominant FRP reinforced beams indicated stiffness degradation under cyclic loading due to the progressive cracking of concrete and associated softening in the member, developing approximately 3% lateral drift ratio prior to failure. This level of lateral drift may be considered to be …
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Tensile Fatigue Damage and Degradation of Random Short-Fiber Smc Composite
Fatigue damage and degradation in a random short-fiber SMC-R50 composite are investigated experimentally and theoretically. In the study of homogeneous damage, experiments were conducted to examine fundamental mechanisms and characteristics of fatigue damage and its evolution. The statistical …
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