Abstract: Monitoring the physical state of a structure and detect damage at an early stage is a v... more Abstract: Monitoring the physical state of a structure and detect damage at an early stage is a very important as it allows to implement measures to correct and improve the safety and reliability of the structure. This paper presents a methodology for detecting structural damage using nondestructive techniques, pricing strategies based on the modal properties of the structure and optimization techniques based on genetic algorithms. The main component of the damage detection methods use changes in the dynamic properties of the structure. The modal parameters are a function of physical properties, therefore, changes in physical properties will cause changes in modal properties. The method has been tested for various damage scenarios, the proposed genetic algorithm evaluates the location and severity of damage in a structure, providing many advantages over traditional methods.
Steel buildings with tubular columns showed a satisfactory performance during the Honshu (2011) e... more Steel buildings with tubular columns showed a satisfactory performance during the Honshu (2011) earthquake, unlike steel buildings in the 1994 Northridge and 1995 Kobe earthquakes, where welded moment connections showed damage in their joints. In this research, a lateral joint using a hollow structural section (HSS)-beam and HSS-column subjected to cyclic displacement was performed. Three large-scale specimens were tested and a numerical model was calibrated, reaching a good adjustment. Later, several configurations of beams and columns were evaluated using finite element (FE) models from the numerical model previously calibrated. A flexural resistance higher 0.80 Mp at 0.04 [rad] was obtained for all cases studied. The ductility factor in the 3 specimens was lower than 2.5, therefore a non-ductile behavior was controlled in the connection. This aspect is very important although a 0.8 Mp at 0.04 [rad] was achieved. Finally, the typical welded moment connection can be improved using ...
The aim of this work was to study the kinetics of thermal degradation of coconut fibers untreated... more The aim of this work was to study the kinetics of thermal degradation of coconut fibers untreated and treated, extracted from the cement matrix at different concentrations and ages of curing, by thermogravimetric analysis. In calculating the temperature of onset (onset) and end (endset) decomposition of the fiber is used the method of integrating the first derivative. The integral method proposed by Coast-Redfern was used to determine the kinetic parameters in the degradation of the fibers from the temperature and mass data generated by the TGA, for a constant heating rate and an inert atmosphere of nitrogen. It was found that the fibers undergo further degradation in the cement matrix to the extent that increase the days of curing. Untreated fibers with short size distribution have an increased decomposition in the cement matrix containing fibers , as corroborated by the activation energy for 128 days of curing. Chemical treatment with PMMA fibers protects alkaline etching of concrete at different ages of curing. Likewise thermogravimetric analysis allows to conclude that factors such as the days of curing, the percentage by volume and the size distribution of the fibers to be significant on the resistance of concrete mixtures.
In: Venezuela. Universidad de los Andes. Departamento de Estructuras. Memorias : 8 seminario lati... more In: Venezuela. Universidad de los Andes. Departamento de Estructuras. Memorias : 8 seminario latinoamericano de ingeniería sismo resistente y primeras jornadas andinas de ingenieria estructural. Mérida, Venezuela. Universidad de los Andes. Departamento de Estructuras, ...
Revista De La Facultad De Ingenieria Universidad Central De Venezuela, Dec 1, 2010
En este trabajo se desarrolla un metodo simplificado para la elaboracion de tableros a partir del... more En este trabajo se desarrolla un metodo simplificado para la elaboracion de tableros a partir del Tetra Bric® recuperado de los residuos solidos de origen domestico. Una vez identificado el potencial de aprovechamiento del Tetra Bric® en un sector del Area Metropolitana de Caracas mediante la cuantificacion de las tasas de generacion de residuos y su composicion en las diversos estratos sociales que lo conforman, se procedio a disenar el esquema productivo, preparacion del material que se va a procesar y a la elaboracion del tablero. La caracterizacion del material a procesar se realizo usando tecnicas de microscopia electronica. Para la evaluacion del tablero obtenido, ademas de las pruebas cualitativas: apariencia, consistencia y facilidad de corte con diversos medios, se determino la densidad, contenido de humedad, absorcion de agua y estabilidad dimensional del tablero por inmersion total a 2 y 24 horas, asi como el esfuerzo paralelo a la superficie. Los resultados muestran que mediante el procedimiento desarrollado se obtiene un material con propiedades similares a los tableros compuestos comerciales, requiriendose un acabado superficial para garantizar su estabilidad ante la humedad. ABSTRACT In this paper a simplified method for the manufacturing of boards from Tetra Bric® recovered from household solid waste was developed. Once the recovery potential of the Tetra Bric® was identified in a sector of the Caracas metropolitan area through the quantification of the rates of waste generation and its composition in the social strata (high, medium, and low), we was proceeded to design the production scheme, the preparation of materials for the process and the preparation of the board. The characterization of materials to process was performed using electron microscopy techniques. For the evaluation of the boards obtained, qualitative parameters were determined: appearance, consistency, and ease of cutting with various tools, and quantitative parameters: density, content of moisture, water absorption and dimensional stability of the panels after submersion in water for 2 and 24 h, as well as the tension parallel to the surface. The results show that through the developed procedure, it is feasible to obtain composite panels with properties similar to commercial panels requiring a surface finish to ensure its stability against moisture. Keywords: Recovery of Tetra Bric®, Household solid waste, Agglomerated boards.
A simple method which can be applied in seismic codes to determine the critical angle of seismic ... more A simple method which can be applied in seismic codes to determine the critical angle of seismic incidence and the corresponding peak response of structures subjected to two horizontal components applied along any arbitrary directions and to the vertical component of earthquake ground ...
A simple method which can be applied in seismic codes to determine the critical angle of seismic ... more A simple method which can be applied in seismic codes to determine the critical angle of seismic incidence and the corresponding peak response of structures subjected to two horizontal components applied along any arbitrary directions and to the vertical component of earthquake ground ...
This paper presents a nondestructive global damage detection and assessment methodology based on ... more This paper presents a nondestructive global damage detection and assessment methodology based on the changes in frequencies and mode shapes of vibration of a structural system. The method is applied at an element level using a finite-element model. According to ...
Abstract: Monitoring the physical state of a structure and detect damage at an early stage is a v... more Abstract: Monitoring the physical state of a structure and detect damage at an early stage is a very important as it allows to implement measures to correct and improve the safety and reliability of the structure. This paper presents a methodology for detecting structural damage using nondestructive techniques, pricing strategies based on the modal properties of the structure and optimization techniques based on genetic algorithms. The main component of the damage detection methods use changes in the dynamic properties of the structure. The modal parameters are a function of physical properties, therefore, changes in physical properties will cause changes in modal properties. The method has been tested for various damage scenarios, the proposed genetic algorithm evaluates the location and severity of damage in a structure, providing many advantages over traditional methods.
Steel buildings with tubular columns showed a satisfactory performance during the Honshu (2011) e... more Steel buildings with tubular columns showed a satisfactory performance during the Honshu (2011) earthquake, unlike steel buildings in the 1994 Northridge and 1995 Kobe earthquakes, where welded moment connections showed damage in their joints. In this research, a lateral joint using a hollow structural section (HSS)-beam and HSS-column subjected to cyclic displacement was performed. Three large-scale specimens were tested and a numerical model was calibrated, reaching a good adjustment. Later, several configurations of beams and columns were evaluated using finite element (FE) models from the numerical model previously calibrated. A flexural resistance higher 0.80 Mp at 0.04 [rad] was obtained for all cases studied. The ductility factor in the 3 specimens was lower than 2.5, therefore a non-ductile behavior was controlled in the connection. This aspect is very important although a 0.8 Mp at 0.04 [rad] was achieved. Finally, the typical welded moment connection can be improved using ...
The aim of this work was to study the kinetics of thermal degradation of coconut fibers untreated... more The aim of this work was to study the kinetics of thermal degradation of coconut fibers untreated and treated, extracted from the cement matrix at different concentrations and ages of curing, by thermogravimetric analysis. In calculating the temperature of onset (onset) and end (endset) decomposition of the fiber is used the method of integrating the first derivative. The integral method proposed by Coast-Redfern was used to determine the kinetic parameters in the degradation of the fibers from the temperature and mass data generated by the TGA, for a constant heating rate and an inert atmosphere of nitrogen. It was found that the fibers undergo further degradation in the cement matrix to the extent that increase the days of curing. Untreated fibers with short size distribution have an increased decomposition in the cement matrix containing fibers , as corroborated by the activation energy for 128 days of curing. Chemical treatment with PMMA fibers protects alkaline etching of concrete at different ages of curing. Likewise thermogravimetric analysis allows to conclude that factors such as the days of curing, the percentage by volume and the size distribution of the fibers to be significant on the resistance of concrete mixtures.
In: Venezuela. Universidad de los Andes. Departamento de Estructuras. Memorias : 8 seminario lati... more In: Venezuela. Universidad de los Andes. Departamento de Estructuras. Memorias : 8 seminario latinoamericano de ingeniería sismo resistente y primeras jornadas andinas de ingenieria estructural. Mérida, Venezuela. Universidad de los Andes. Departamento de Estructuras, ...
Revista De La Facultad De Ingenieria Universidad Central De Venezuela, Dec 1, 2010
En este trabajo se desarrolla un metodo simplificado para la elaboracion de tableros a partir del... more En este trabajo se desarrolla un metodo simplificado para la elaboracion de tableros a partir del Tetra Bric® recuperado de los residuos solidos de origen domestico. Una vez identificado el potencial de aprovechamiento del Tetra Bric® en un sector del Area Metropolitana de Caracas mediante la cuantificacion de las tasas de generacion de residuos y su composicion en las diversos estratos sociales que lo conforman, se procedio a disenar el esquema productivo, preparacion del material que se va a procesar y a la elaboracion del tablero. La caracterizacion del material a procesar se realizo usando tecnicas de microscopia electronica. Para la evaluacion del tablero obtenido, ademas de las pruebas cualitativas: apariencia, consistencia y facilidad de corte con diversos medios, se determino la densidad, contenido de humedad, absorcion de agua y estabilidad dimensional del tablero por inmersion total a 2 y 24 horas, asi como el esfuerzo paralelo a la superficie. Los resultados muestran que mediante el procedimiento desarrollado se obtiene un material con propiedades similares a los tableros compuestos comerciales, requiriendose un acabado superficial para garantizar su estabilidad ante la humedad. ABSTRACT In this paper a simplified method for the manufacturing of boards from Tetra Bric® recovered from household solid waste was developed. Once the recovery potential of the Tetra Bric® was identified in a sector of the Caracas metropolitan area through the quantification of the rates of waste generation and its composition in the social strata (high, medium, and low), we was proceeded to design the production scheme, the preparation of materials for the process and the preparation of the board. The characterization of materials to process was performed using electron microscopy techniques. For the evaluation of the boards obtained, qualitative parameters were determined: appearance, consistency, and ease of cutting with various tools, and quantitative parameters: density, content of moisture, water absorption and dimensional stability of the panels after submersion in water for 2 and 24 h, as well as the tension parallel to the surface. The results show that through the developed procedure, it is feasible to obtain composite panels with properties similar to commercial panels requiring a surface finish to ensure its stability against moisture. Keywords: Recovery of Tetra Bric®, Household solid waste, Agglomerated boards.
A simple method which can be applied in seismic codes to determine the critical angle of seismic ... more A simple method which can be applied in seismic codes to determine the critical angle of seismic incidence and the corresponding peak response of structures subjected to two horizontal components applied along any arbitrary directions and to the vertical component of earthquake ground ...
A simple method which can be applied in seismic codes to determine the critical angle of seismic ... more A simple method which can be applied in seismic codes to determine the critical angle of seismic incidence and the corresponding peak response of structures subjected to two horizontal components applied along any arbitrary directions and to the vertical component of earthquake ground ...
This paper presents a nondestructive global damage detection and assessment methodology based on ... more This paper presents a nondestructive global damage detection and assessment methodology based on the changes in frequencies and mode shapes of vibration of a structural system. The method is applied at an element level using a finite-element model. According to ...
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