Asian journal of civil engineering
Volume:12 Issue: 6, Dec 2011

In this paper, the seismic behavior of three intermediate moment-resisting concrete spaceframes with unsymmetrical plan in five, seven and ten stories are evaluated by usingpushover analysis. In each of these frames, both projections of the structure beyond areentrant corner are greater than 33 percent of the plan dimension of the structure in the given direction. The performance of these buildings has been investigated using thepushover analysis. Results have been compared with those obtained from non-lineardynamic analysis.

Steel sections with concrete infill are being increasingly used as structural members, sincefilling the steel section with concrete increases both its strength and ductility withoutincreasing the section size. However, the limitations imposed by certain drawbacks ofcement concrete are not alleviated or moderated by the encasing steel tube, like its highshrinkage, creep, brittleness, reactivity and low tensile strength, may be a hindrance to the rapid and diversified application of concrete filled steel tubes in line with current emphasis on ductility-based seismic design. In this context, studies are presently being conducted on filled steel composite members, employing lighter, more ductile, high tensile strength and inert polymer-based fill materials for the steel tube. In the present paper, experimental results of concrete–filled steel columns and polymer modified concrete filled steel columns under axial load combined with lateral cyclic loading are reported. Findings of these studies relating to the hysteresis response of filled steel composite columns subjected to axial compression combined with lateral cyclic load highlight the significant increase in ductility and energy absorption capacity of polymer modified concrete-filled steel columns.

In this paper, the recently developed meta-heuristic optimization algorithm, known as thecharged system search (CSS), is utilized for the problems of facility locations on a network.The CSS is an optimization algorithm that acts on the basis of the interaction betweencharged particles (CPs) considering the governing laws of Coulomb and Gauss fromelectrical physics and laws of motion from Newtonian mechanics.

The present study investigated the flexural response and ductile behaviour of PrefabricatedCage Reinforced Concrete (PCRC) beams. The Prefabricated Cage System (PCS) isfabricated by perforating hollow cold formed steel tubes or steel sheets. The resulting PCSacts as transverse and longitudinal reinforcing steel, working compositely with thesurrounding concrete to resist the applied loads. This new and innovative system eliminatessome of the weaknesses and detailing problems inherent in traditional Reinforced Concrete Construction. Nine beam specimens reinforced with Prefabricated Cage System were tested under monotonic loading. The effects of thickness of cold formed steel sheet and Grade of Concrete on parameters such as moment curvature, load deflection, ductility and energy absorption were experimentally determined. All beams exhibited considerable amount of deflection, which provide ample warning to the imminence failure. Final failure of PCRC beams were found to occur in pure bending region. The results reveal that PCRC beams show better ductile performance and energy absorption capacity due to the confinement provided by PCS. Displacement and curvature ductility factor for all beams were found and discussed in this paper.

Aboveground steel tanks are widely utilized in residential and industrial areas, and assurance of their seismic safety is a very important engineering consideration. In this paper, nonlinear response of these tanks using a new dynamic pushover procedure called Endurance Time (ET) method along with conventional nonlinear response history (RHA) is studied. The comparison between the results of RHA and ET method shows reasonable consistency.Based on the level of accuracy observed in this research, it is concluded that ET method can effectively be used in predicting seismic performance of anchored tanks. By considerably reducing the number of required response history analyses for estimating the response at various excitation levels, ET method has a good potential in paving the way for practical application of response history based analysis and design procedures for thin walled structures such as steel tanks.

Analytical solutions based on general differential equations and finite element formulationsfor in-plane analysis of composite steel/concrete beams including the effects of partialinteraction are presented in this study. The partial shear interaction, which happens as aresult of having flexible shear connections, brings about lower flexural rigidities,particularly in hogging regions of the composite beams. The presented analytical solutioncan be used to calculate the in-plane critical stress resultants that may initiate the out-ofplane buckling of the steel joist. Unlike the published works, the current finite elementmodel accommodates the partial shear interaction and general loading and end supportconditions, and also accounts for the variation of beam’s flexural rigidities in hogging andsagging regions. Numerical examples are provided to demonstrate the accuracy, efficiencyand versatility of the derivations.

Electronic waste or waste electronic and electrical equipment is an emerging issue posingserious pollution problems to the human and the environment. New effective wastemanagement options need to be considered especially on recycling concepts. This paperpresents the results of an investigation to study the performance of concrete prepared with Eplastic waste as part of coarse aggregate. An effort has been made to detail a systematic study of compressive strength of concrete with various proportions of E-waste as coarse aggregate in concrete. The test results showed that a significant improvement in compressive strength was achieved in the E-plastic concrete compared to conventional concrete. The tests were also designed to evaluate the internal pore structure, its chemical resistance to environmental agents and reactivity with some components of the cement. The results indicated that the E-plastic aggregate up to 15% weight of the coarse aggregate and replacement of cement with fly ash (10% by weight) can be used effectively in concrete and thus results in waste reduction and resources conservation.

Infill walls can introduce changes in the dynamic characteristics of frames due to theirfeatures and their connection to the frames. Among the methods applied for modeling infill walls, micro modeling is able to model the infill wall and compound frame behaviors very close to their real time functioning, using Finite elements Method. In this paper, concrete frames and brick walls micro modeling technique, through application of the ANSYS 12 software is described firstly, followed by the software analysis results of 36 reinforced concrete frames with different number of stories and bays and various positioning patterns for inter panel walls, under the increasing cyclic lateral loads. The impact of infill walls on seismic behavior of structures including several patterns of hysteresis loops, the area under hysteresis loops (the amount of dissipated energy), ductility and primary stiffness are ultimately assessed.