Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
The use of external posttensioning technique for strengthening reinforced concrete girders has been considerably studied by many\nresearchers worldwide. However, no available data are seen regarding strengthening full-scale composite prestressed concrete\ngirders with external posttensioned technique under static and repeated loading. In this research, four full-scale composite\nprestressed I-shape girders of 16m span were fabricated and tested under static and repeated loading up to failure. Accordingly,\ntwo girders were externally strengthened with posttensioned strands, while the other two girders were left without strengthening.\nThe experimental tests include deflection, cracking load, ultimate strength and strains at midspan, and loading stages. Test results\nwere compared with the design expressions mentioned in AASHTO LRFD specifications and ACI 318-2014 code. Also,\na nonlinear analysis was conducted using the finite element method (FEM). The presented analysis models were verified by\ncomparing the model results with test results. The general theme abstracted from both experimental tests and numerical analysis\nreflects that the performance and procedure of strengthening with external prestressing of girders were found to be effective in\nincreasing the load carrying capacity of the strengthened girders....
Fatal train accidents usually involve derailments or collisions. These derailment/collision accidents are infrequent. However, the\ndamage due to derailment can be catastrophic. Derailment containment walls are usually used in Korea to minimize such\ndamages. However, the impact forces that are needed to design the derailment containment walls were not well defined, and only\nlimited studies were conducted for the behavior of the derailment containment walls. In this study, the focus was made on the\nimpact force analysis of the containment wall through a series of 3D collision simulation after train derailment. Finite element\nmodeling was conducted to analyze the dynamic behavior of the derailed train that collides with a structure such as containment\nwall using the LS-DYNA analysis software application. The FE models of car bodies, bogie frames, and wheel sets were created\nsuch that full conformity was achieved between their numerical models and actual vehicles with respect to the masses and\nprincipal mass moments of inertia. In addition, various installation situations of the containment wall were considered for the\ncollision simulation. Finally, the economical alternative method to reduce the impact force was proposed....
This research focuses on the use of adaptive artificial neural network system for evaluating the skid resistance value (British\nPendulum Number; BPN) of the glass fiber-reinforced tiling materials. During the creation of the neural model, four main factors\nwere considered: fiber, calcium carbonate content, sand blasting, and polishing properties of the specimens. The model was\ntrained, tested, and compared with the on-site test results. As per the comparison of the outcomes of the study, the analysis and\non-site test results showed that there is a great potential for the prediction of BPN of glass fiber-reinforced tiling materials by using\ndeveloped neural system....
Masonry construction is themost widely used buildingmethod in the world. Concretemasonry is relatively low in cost due to the vast\navailability of aggregates used within the production process. These aggregatematerials are not always reliable for structural use. One\nof the principal issues associated with masonry is the brittleness of the unit. When subject to seismic loads, the brittleness of the\nmasonry magnifies. In regions with high seismic activity and unspecified building codes or standards, masonry housing has\ndeveloped into a death trap for countless individuals. A common approach concerning the issue associated with the brittle\ncharacteristic ofmasonry is addition of steel reinforcement. However, this can be expensive, highly dependent on skillfulness of labor,\nand particularly dependent on the quality of available steel. A proposed solution presented in this investigation consists of introducing\nsteel fibers to the lightweight aggregate concrete masonry mix. Previous investigations in the field of lightweight aggregate\nfiber-reinforced concrete have shown an increase in flexural strength, toughness, and ductility. The outcome of this research project\nprovides invaluable data for the production of a ductile masonry unit capable of withstanding seismic loads for prolonged periods...
Architectural design concepts incorporating glass beams, panels, or generally load-carrying elements and stiffeners for buildings,\ncladdings, windows, and partitions are largely considered in modern high-rise constructions. A multitude of aspects, including\nmotivations related to transparency, aesthetics, illumination, and energy conservation, progressively increased the use and interest\nfor such a still rather innovative constructional material. However, compared to other traditional materials for buildings, standard\nglass is typically characterized by brittle behaviour and limited tensile resistance. The intrinsic properties of glass, moreover,\ntogether with typically limited thickness-to-size ratios for glazing elements, or the mutual interaction of glass components with\nadjacent constructional elements as a part of full assemblies they belong (i.e., fixing systems, sealants, etc.), as well as the\ncombination of mechanical and thermal phenomena, make glass structures highly vulnerable. Special safety design rules are\nhence required, especially under extreme loading conditions. In this review paper, a state of the art on structural glass systems\nexposed to fire is presented. Careful consideration is paid for actual design methods and general regulations, as well as for\nexisting research outcomesââ?¬â?both at the material and assembly levelsââ?¬â?giving evidence of current challenges, issues, and\ndevelopments....
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