Browsing by Autor "Fernando Palacios Galarza"

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Compressive Behaviour of Square CFDST Short Columns with Double Inner Steel Tubes
(Trans Tech Publications, 2022) Fernando Palacios Galarza; Joaquín Humberto Aquino Rocha
This study focuses on the experimental analysis of concrete-filled double-skin tubular (CFDST) short columns with double circular inner steel tubes under concentric axial loading. This cross-section layout promises to increase the ductile behavior of the compressive element and its energy absorption capacity, not to mention its ultimate axial strength. This research analyses main twofold variables: (i) Hollow ratio and (ii) eccentricity ratio (i.e., distance ratio between the inner tube’s separation and the sandwiched concrete width). As a result, load Vs. Axial deformation, load Vs. Axial strain curves, ductility index, strength index, energy absorption capacity, and ultimate axial capacity formulae for square CFDST columns with double circular inner tubes are reported. Key findings of this study show that (a) ductility is an intrinsic property of these types of sections; (b) the variation effect of hollow ratio influence inversely in the confined concrete strength of the element, (c) Eccentricity ratio has proved to be the least ultimate strength capacity influencer. However, its impact increases when it is jointly analyzed with the hollow ratio values. (d) The formulae proposed for predicting the ultimate capacity of CFDST columns showed good agreement with the experimental results. Thus, these expressions could be extended to the design of composite CFDST elements, provided a resistance factor based on a reliability analysis is incorporated.
Compressive Strength Assessment of Soil–Cement Blocks Incorporated with Waste Tire Steel Fiber
(Multidisciplinary Digital Publishing Institute, 2022) Joaquín Humberto Aquino Rocha; Fernando Palacios Galarza; Nahúm Gamalier Cayo Chileno; Marialaura Herrera Rosas; Sheyla Perez Peñaranda; Luis Ledezma Diaz; Rodrigo Pari Abasto
The rapid growth in waste tire disposal has become a severe environmental concern in recent decades. Recycling rubber and steel fibers from wasted tires as construction materials helps counteract this imminent environmental crisis, mainly improving the performance of cement-based materials. Consequently, the present article aims to evaluate the potential use of waste tire steel fibers (i.e., WTSF) incorporated in the manufacture of soil-cement blocks, considering their compressive resistance as a primary output variable of comparison. The experimental methodology applied in this study comprised the elaboration of threefold mixtures of soil-cement blocks, all of them with 10% by weight in Portland cement, but with different volumetric additions of WTSF (i.e., 0%, 0.75%, and 1.5%). The assessment's outcomes revealed that the addition of 0.75% WTSF does not have a statistically significant influence on the compressive resistance of the samples. On the contrary, specimens with 1.5% WTSF displayed a 20% increase (on average) in their compressive strength. All the tested samples' results exhibited good agreement with the minimum requirements of the different standards considered. The compressive resistance was evaluated in the first place because it is the primary provision demanded by the specifications for applying soil-cement materials in building constructions. However, further research on the physical and mechanical properties of WTSF soil-cement blocks is compulsory; an assessment of the durability of soil-cement blocks with WTSF should also be carried out.
Influence of Plaster Coating Thickness on the Thermal Behavior of Brick Masonry Walls
(Trans Tech Publications, 2022) Pedro Igor Bezerra Batista; Joaquín Humberto Aquino Rocha; Thamires C.M. de França; Fernando Palacios Galarza; Yêda Vieira Póvoas
A ready-witted selection of high-quality construction materials for walls and roofs provides greater well-being and thermal comfort for building co-owners. It also reduces energy consumption with artificial conditioning appliances. This research aimed to analyze the thermal behavior of a ceramic brick masonry prototype composed of an external coating of Portland cement mortar and an internal plaster coating with variable thickness. Tests were carried out in a thermal chamber, and the temperatures were recorded by a non-contact thermographic camera and conduction thermocouples measuring equipment. Hence, the parameters obtained were fourfold: thermal resistance, thermal capacity, thermal transmittance, and thermal delay. The four latter were calculated as per the simplified method proposed in the Brazilian specification for Thermal performance in buildings (i.e., NBR 15220-1). As a result, the thicker plaster-coated block prototype showed a minor temperature variation during the heating process. Thus, the thickness of the plaster coating possesses a direct influence on the thermal response of the brick; The thicker the coating becomes, the better the thermal performance of the structural element.
Mechanical Properties Evaluation of Render Mortars with Different Waterproof Additive Compositions
(Trans Tech Publications, 2021) Joaquín Humberto Aquino Rocha; Fernando Palacios Galarza
Waterproof additives and bonding agent mixtures are commonly employed in the setting up of render mortars. This practice often shows beneficial results, enhancing the properties of the common mortars. Yet, the use of these additives does not seem to have a direct effect on the mechanical properties of the mortars. This study thus aims to evaluate the influence of the use of waterproof and adhesion additives on the mechanical properties of render mortars. Based on their chemical composition, three different types of mortar admixtures were evaluated, using fourfold additive-mortar weight ratios: 0%, 1.5%, 3%, and 5%. Compressive and flexural strength tests were conducted after 28 days. The results showed a negative impact on the mechanical properties of the mortars. The lowest flexural and compression strength values reported are 1.52 and 4.57 (MPa), respectively. However, all compressive and flexural strength values lied within the limit range recommended by the “Mortars applied on walls and ceilings” construction code (i.e., ABNT NBR 13281). It is compulsory to continue the experimental tests to determine render mortars mechanical properties with higher waterproof additive-mortar weight ratios since higher ratios might produce mortars with non-allowed mechanical properties.