Advanced Engineering Forum Vol. 26
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摘要: Current practice for seismic design of earth structures considers the use of displacement-based methods, which allow a quick and quantitative estimation of the movement of soil masses under earthquake loading. This type of procedures are aimed to establish a relationship between (i) the main earthquake parameters, (ii) the critical acceleration, and (iii) the corresponding permanent displacements of the soil structure. In this sense, based on the well-known Newmark’s sliding block method, several regression models intended for design purposes have been proposed during last decades. However, the selection of an appropriate method to predict the expected permanent displacements of a soil mass remains a difficult and somewhat arbitrary practice. In this paper, strong-motion records from four major Chilean earthquakes, grouped by soil conditions, are used to compare and evaluate the suitability of the reviewed methods for assessing the seismic performance of earth structures. From the results obtained, general conclusions and recommendations for practical applications on sites with similar characteristics to the Chilean subduction zone are elaborated.
摘要: This paper presents the analysis of the effect of smoke exhaust and hot gases from an atrium type building using techniques for numerical simulation of a fire situation. Several scenarios regarding smoke exhaust are considered for that purpose and the variation of the following parameters is monitored: minimum and maximum temperature of hot gases as well as the smoke layer height inside the atrium. Using engineering techniques, the development of fire, in compliance with the European legislation has been modelled, by means of a specialized computer program in order to simulate the phenomena of both the fluid flow and the heat transfer manifested in a fire situation.
摘要: The partially infilled frames are considered vulnerable in terms of captive column effect for the events of earthquakes. Many reinforced concrete buildings have been affected due to captive column effects. Experimental study has been done to verify the captive column effect and its failure modes for partially infilled frames and the results have been compared with the ones obtained for a bare frame subjected to lateral loading. The results of experimental study have also been compared with some analytical results and the verification of equivalent strut width proposed by one of the authors has been done. From the experimental point of view, it is understandable that due to lateral loading to partially infilled frames, the damage pattern is diagonal and the failure of column occurs at the column-wall joint at the upper side of the wall. It is also seen that for fifty percent partially infilled frames, the stiffness of bare frame is enhanced slightly, however, the failure in the column during lateral loading indicates that the columns are subjected to high shear due to the presence of partial infill.
摘要: The fire safety regulations in Romania require that in case of a fire occurring into a building, it should be prevented to spread to any adjacent structure or neighbouring façade. Apart from the minimum prescribed distances between the buildings, there is no other benchmark or guidance for an approved calculation method to prove compliance with this provision. The British regulations have specified that the heat fluxes on the surfaces exposed to radiation from a fire within the adjacent buildings should not exceed a heat flux of 12.6 kW/m2. The purpose of this article is to review some of the empirical calculation methods for the incident radion flux given in the international literature and to compare their results for a practical aplication.
摘要: A case study including a detailed ground settlement analysis is made for a particular loess structure located in the city of Galati, Romania, in order to assess the interdependence of geo-environmental and anthropic settlement triggering factors in the urban system context. In the first part of the study, loess behavior and its effects on built environment are analyzed and discussed based on worldwide historic expertise and current issues. An integrative analysis of loess deposits in natural state, with reference to induced-hydraulic and stress conditions, which was performed by laboratory and in-situ investigations, is then reported. An assessment of basic geotechnical parameters, as well as small-scale modeling of loess settlements at wetting under self-weight were conducted in order to select the most representative experimental area, from the point of view of specific soil structure behavior. Field monitoring surveys were performed to obtain information for quantitative evaluation of settlement time-dependent evolution, by the simulation of excessive moisture. The processing and analysis of experimental data gathered for natural and improved ground conditions revealed that the settlement amplitude of loess deposits with high sensitivity to wetting under self-load can be significantly reduced by the selection of adequate consolidation solutions, based on realistic and undisturbed environmental conditions. The study of soil structure behavior under simultaneous settlement-triggering factors can be integrated in multi-hazard analysis as a support for efficient strategies and mitigation measures, with applicability in the urbanization process, building and foundation design and environmental protection.
摘要: In reinforced concrete buildings in case of a possible earthquake, the buildings slamp as they lost their horizontal stability because of hinging of column ends. The assumptions for plastic hinge lengths are present during project stage of reinforced concrete buildings. According to Turkish Earthquake Regulations, although plastic hinge length is determined to be 0.5h, it's known that plastic hinge length is determined via various formulas in some other regulations all over the world. In reinforced concrete columns, it's necessary to indicate the effect of plastic hinge length on the column behavior. For this purpose, pushover analysis of 5 column samples having different plastic hinge lengths was performed with non-linear analysis program. As a result of pushover analysis, situations of plastic hinges formed in columns and their load-displacement curves were determined. The graphs and the data were compared and the results were discussed.
摘要: The fire safety objectives are primarily focused on life safety issues. In addition, for particular cases, property protection and business continuity are taken into account when developing Fire Safety Strategies. The purpose of this article is to assess the fire risk associated with a timber structure within an atrium space, carrying out a qualitative and quantitative analysis.For probabilistic risk assessments, the criteria are set such that the probability of a given undesirable event is acceptably low, or As Low As Reasonably Practicable (ALARP). The acceptance criteria vary depending on the fire safety objectives, therefore, for this study, the property protection has been considered beside the life safety of the occupants.
摘要: The paper presents a case study of a greenhouse building affected by wind loads. The building is a lightweight steel structure with a height of 7.1meters, 12.8 meters wide and 171m long. The roof of the building is a lattice cupola. The main purpose of the authors was to find solutions in order to reduce wind loads on the building envelope, using some wind protection barriers. In order to identify the optimal solution, different types of wind barriers were analyzed. Using Ansys CFX, the authors carried out numerical simulation for each type of wind barrier, in order to find out which reduces the most the wind pressures on the walls and on the roof of the analyzed building. The results provided by numerical simulation of wind action on the building were used to make a comparative study between different patterns of wind fences. The comparison between pressures developed on the walls and roof for each type of fence, has allowed the choice of an optimal solution that can be applied also to other similar buildings.
摘要: In the current economic climate, agriculture has started to become one of the main areas of economic activity, including economically powerful states. One of the main problems in this industry is lack of storage space and maintaining quality of grain. Storing grain in silo structures ensure their high quality, efficient protection against the factors that lead to damage and allows keeping all season long and against climatic factors. Take into account the demands of modern agriculture productivity and high efficiency, silos have such an important economic role in the industry. The silos are in the top of industrial equipment that might experience during the lifetime cycle structural failure. Among the causes of structural failure it might be also the effect of seismic action. The silos located in seismic areas are exposed to extreme seismic loads. This paper presents the FE analysis results of the behavior of a circular metal silos located in seismic areas, taking into account the interaction of the granular material stored with the silo wall. The simulation of the contact surfaces of granular material and silo wall have been done based on Drucker - Prager model, available in ANSYS software vs.1.5. Influences of granular material characteristics stored up shall be also investigated and the results are highlighted in this paper.