Examinando por Materia "Degrees of freedom (mechanics)"
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Ítem Base shear determination using response-spectrum modal analysis of multi-degree-of-freedom systems with soil–structure interaction(Springer Netherlands, 2019-01-01) Arias H.; Jaramillo J.D.; Mecánica AplicadaBuilding codes and design guidelines, e.g. FEMA (NEHRP recommended seismic provisions for new buildings and other structures, FEMA P-1050, Washington, 2015) and ASCE (Minimum design loads for buildings and other structures ASCE/SEI 7-10/2010, Reston, 2010), describe the problem of multi-degree-of-freedom systems with soil-structure interaction (SSI). These systems are modeled like those having a fundamental degree of freedom on a foundation with lateral and rotational interactions and the other vibration modes isolated and supported on a fixed foundation. This model oversimplifies the problem, neglecting the effects of having all modes coupled in the foundation with SSI. A simple, easily programmable, SSI model in which all vibration modes are coupled an attached to an infinitely rigid shallow foundation subjected to soil excitation is introduced here. Initially, the total response of the coupled system is calculated. Then, using traditional procedures to combine modal responses, a simplified alternative methodology to find the total response of this coupled system is proposed. The new methodology is verified against a robust numerical technique, i.e. boundary elements method, using a wide variety of cases that combine several types of soils, building heights and two structural typologies: bending frames and shear walls. Finally, it is clear from the parametric study that current methodologies, based only on the interaction of the fundamental mode of vibration of the structure, in some cases has a significant influence on the total base shear of buildings, particularly in tall buildings founded in soft soils. © 2019, Springer Nature B.V.Ítem Development of a fragility model for the residential building stock in South America(EARTHQUAKE ENGINEERING RESEARCH INST, 2017-05-01) Villar-Vega, Mabe; Silva, Vitor; Crowley, Helen; Yepes, Catalina; Tarque, Nicola; Acevedo, Ana Beatriz; Hube, Matias A.; Gustavo, Coronel D.; Maria, Hernan Santa; Mecánica AplicadaSouth America-in particular, the Andean countries-are exposed to high levels of seismic hazard, which, when combined with the elevated concentration of population and properties, has led to an alarming potential for human and economic losses. Although several fragility models have been developed in recent decades for South America, and occasionally used in probabilistic risk analysis, these models have been developed using distinct methodologies and assumptions, which renders any direct comparison of the results across countries questionable, and thus application at a regional level unreliable. This publication aims at obtaining a uniform fragility model for the most representative building classes in the Andean region, for large-scale risk analysis. To this end, sets of single-degree-of-freedom oscillators were created and subjected to a series of ground motion records using nonlinear time history analyses, and the resulting damage distributions were used to derive sets of fragility functions. © 2017, Earthquake Engineering Research Institute.Ítem Development of a fragility model for the residential building stock in South America(EARTHQUAKE ENGINEERING RESEARCH INST, 2017-05-01) Villar-Vega, Mabe; Silva, Vitor; Crowley, Helen; Yepes, Catalina; Tarque, Nicola; Acevedo, Ana Beatriz; Hube, Matias A.; Gustavo, Coronel D.; Maria, Hernan Santa; Villar-Vega, Mabe; Silva, Vitor; Crowley, Helen; Yepes, Catalina; Tarque, Nicola; Acevedo, Ana Beatriz; Hube, Matias A.; Gustavo, Coronel D.; Maria, Hernan Santa; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de IngenieríaSouth America-in particular, the Andean countries-are exposed to high levels of seismic hazard, which, when combined with the elevated concentration of population and properties, has led to an alarming potential for human and economic losses. Although several fragility models have been developed in recent decades for South America, and occasionally used in probabilistic risk analysis, these models have been developed using distinct methodologies and assumptions, which renders any direct comparison of the results across countries questionable, and thus application at a regional level unreliable. This publication aims at obtaining a uniform fragility model for the most representative building classes in the Andean region, for large-scale risk analysis. To this end, sets of single-degree-of-freedom oscillators were created and subjected to a series of ground motion records using nonlinear time history analyses, and the resulting damage distributions were used to derive sets of fragility functions. © 2017, Earthquake Engineering Research Institute.Ítem Finite element modeling of micropolar-based phononic crystals(Elsevier BV, 2019-11-11) Guarín-Zapata N.; Gomez J.; Valencia C.; Dargush G.F.; Hadjesfandiari A.R.; Mecánica AplicadaThe performance of a Cosserat/micropolar solid as a numerical vehicle to represent dispersive media is explored. The study is conducted using the finite element method with emphasis on Hermiticity, positive definiteness, principle of virtual work and Bloch–Floquet boundary conditions. The periodic boundary conditions are given for both translational and rotational degrees of freedom and for the associated force- and couple-traction vectors. Results in terms of band structures for different material cells and mechanical parameters are provided. © 2019 Elsevier B.V.