Current Issue : October - December Volume : 2020 Issue Number : 4 Articles : 5 Articles
The transition from experimental studies to the realm of numerical simulations is often\nnecessary for further studies, but very difficult at the same time. This is especially the case for\nextended seismic analysis and earthquake-resistant design. This paper describes an approach to\nmoving from the experimental testing of an elementary part of a wood-frame building structure to\na numerical model, with the use of a commercial engineering analysis software. In the presented\napproach, a timber-frame structure with polyurethane (PU)-foam insulation and OSB (oriented\nstrand board) sheathing was exposed to dynamic excitation. The results were then used to generate\na numerical 3D model of the wooden frame element. The process of creating the 3D model is\nexplained with the necessary steps to reach validation. The details of the model, material properties,\nboundary conditions, and used elements are presented. Furthermore, the authors explain the technical\npossibilities for simplifying the numerical model in used software. Simplifying the model leads to a\nsubstantial reduction of calculation time without the loss of accuracy of results. Such a simplification\nis especially useful when conducting advanced numerical calculations in the field of seismic and\ndynamic resistant object design....
The use of non-renewable resources by the construction industry has several\nenvironmental consequences, contributing to excessive energy consumption\nand loss of materials. So, the construction sector is always in search of improvement\nand methods that innovate the existing techniques, aiming at the\nuse of alternative and sustainable materials. Bamboo is a perennial plant with\nfast growth rate and low cost that has great physical and mechanical characteristics\nthat assure its performance in the building environment. The use of\nbeams with total or partial replacement of steel by bamboo has been well studied,\ndue to the possibility of using the same design methods used in reinforced\nconcrete beams, since the bamboo-reinforced beams meet the Bernoulli-\nKirchoff bending theory. The objective of the work was to adapt a design\nprocedure into an electronic spreadsheet for bamboo reinforced concrete\nbeams subjected to four-point bending, with rectangular section, according to\nBrazilian Standard NBR 6118 (2014). The spreadsheet was tested based on\nother authors taking into consideration a steel double reinforcement. The resulting\nvalues were equivalents to those obtained by the authors, validating\nthe efficiency of the worksheet. This methodology aims to optimize the design\nprocess of beams and enable the substitution of steel by bamboo, highlighting\nthe validation, from the structural point of view, obtained by the\nauthors....
To understand the structural damage evolution process of loess under the action of dry-wet cycles, a triaxial test of a dry-wet cycle\nwas performed by considering three influencing factors: initial moisture content, amplitude of the dry-wet cycle, and number of\ndry-wet cycles. The stress-strain curves of undisturbed loess samples at different cycling times vary under different compacted\nloess cycles. Under the same axial strain, the stress value of the undisturbed loess is higher than that of the loess sample after a drywet\ncycle, indicating that such cycle can reduce the strength of loess. As the number and amplitude of dry-wet cycles increase, the\nshear strength of the loess sample and the value of cohesion (c) of the strength index gradually decrease, and the amplitude\ngradually decreases. With an increase in the number and amplitude of dry-wet cycles, the change in the internal friction angle of\nthe strength index is inevident, indicating that the effect of dry-wet cycles on the internal friction angle of loess is insignificant.\nComputed tomography (CT) scan experiments were also conducted to obtain the evolution of loess cracks before and after a drywet\ncycle. Studies have shown that as the number and amplitude of dry-wet cycles increase, the mean (ME) value of CTdecreases,\nthe standard deviation (SD) value increases, and the ME value is obtained during the initial stage of a dry-wet cycle. Meanwhile,\nthe decreasing trend of ME and the increasing trend of SD values are most evident during the period of a dry-wet cycle. In\nconclusion, dry-wet cycles promote the development of cracks....
In order to create more underground space, it was important to investigate the impact of excavation on the preexisting building. In\nthis paper, a scale model test was conducted to analyze the stability of the structure during excavation. The model consisted of\nunderpinning piles preinstalled in clay, with a reinforced concrete building placed on underpinning piles. The strain and\nsettlement of the structure were observed to reveal the time settlement of columns and the time strain of beams, columns, and piles\nduring excavation. The results showed that the strain change of beams was small, and strain values of columns were getting higher.\nAnd underpinning piles had great strain variations. They were of great significance to underpinning design and\nengineering practice....
In order to study the influence of traveling wave effect on the seismic response and damping effect of suspended structure, a series of\nshaking table tests of the 1 : 20 suspended structure have been carried out to compare and analyze the dynamic responses of\nsuspended structures under two points and a consistent input. The vibration damping effect and vibration reduction law of\nsuspended structure are discussed at different apparent wave velocity and in the different connection. The research shows that the\ndamping suspended structure has a good damping effect, and the amplitude reduction of the top displacement peak response is up to\n15%, which corresponds to smaller apparent velocities. Moreover, the upper bound of the maximum acceleration response at the\nstructuresâ?? top under nonuniform input motions equals that of the uniform motion. However, there is a hysteresis in the acceleration\nresponse under wave travelling excitations, and the smaller the apparent wave velocity, the more obvious the hysteresis....
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