Current Issue : April - June Volume : 2016 Issue Number : 2 Articles : 5 Articles
An analytical model able to evaluate the bondslip\nlaw of confined reinforced concrete elements is developed\nand presented in this paper. The model is based on the\nstudies developed by Tepfers and by den Uijl and Bigaj on\nthe thick-walled cylinder model and extended to the case of\nthe presence of transverse reinforcement. The bond strength\nand the considered failure modes (splitting or pull-out failure)\nare expressed as a function of the geometrical (concrete\ncover and transverse reinforcement) and mechanical (concrete\nstrength) parameters of the element. The application of\nthe proposed methodology allows to forecast the failure\nmode, and equations for the bond-slip law are finally proposed\nfor a range of steel strain lower than the yielding one....
The paper studied the behavior of reinforced\nconcrete triangular and T-beams. Three reinforced concrete\nbeams were tested experimentally and analyzed analytically\nusing the finite element method. Their reliability was\nalso assessed using the reliability index approach. The\nresults showed that the finite element vertical displacements\ncompared well with those obtained experimentally.\nThey also showed that the vertical displacements obtained\nusing the finite element method were larger than those\nobtained experimentally. This is a strong indication that the\nfinite element results were conservative and reliable. The\nresults showed that the triangular beams exhibited higher\nductility at failure than did the T-beam. The plastic\ndeformations at failure of the triangular beams were higher\nthan that of the T-beam. This is a strong indication of the\nhigher ductility of the triangular beams compared to the\nT-beam. Triangular beams exhibited smaller cracks than\ndid T-beams for equal areas of steel and concrete. The\ndesign moment strengths Mc computed using the American\nConcrete Institute (ACI) design formulation were safe and\nclose to those computed using experimental results. The\nexperimental results validated the reliability analysis\nresults, which stated that the triangular beams are more\nreliable than T-beams for equal areas of steel and concrete....
Despite the extensive research on the seismic behavior of infilled\nframes since 1960�s, there is no general consensus towards a unified\napproach. Purpose of this study is to review the existing analytical and\nexperimental research, as well as code provisions, on masonry and on\nreinforced concrete infilled frames. The basic characteristics of infilled\nframes and how these affect seismic performance are summed up. Different\napproaches of the equivalent strut, broadly used for modeling of the infilled\nframes, are thoroughly discussed....
Through evolution of building design codes in active seismic regions, life safety performance limit state has been met.\nUnacceptably high economic loss during the 1994 Northridge and 1995 Kobe earthquakes, however, has brought forward a new design\nparadigm: performance-based earthquake engineering (PBEE). In this study, the PBEE is extended to study: (1) effect of three earthquake\ntypes, namely shallow crustal earthquakes, deep in-slab earthquakes, and megathrust Cascadia interface earthquakes, on loss assessment;\n(2) consideration of main shockââ?¬â??aftershock (MS-AS) sequences as earthquake excitation; and (3) multivariate seismic demand modeling for\nmulti criteria seismic performance evaluation. This is applied to a 4-story non ductile reinforced concrete (RC) frame located in Victoria,\nBritish Columbia (BC), Canada. Through this case study, it is highlighted that the sources of ground motion have significant effects on loss\nassessment. Furthermore, influences of MS-AS earthquake sequences and multivariate seismic demand models on the expected seismic loss ratios\nare in the order of 10%. In light of this, for any future seismic risk management, it is proposed to have an evolutionary assessment framework\nthat is adaptive to the current state of scientific knowledge and evidence....
Tubular steel towers are the most common supporting structure of wind converters. The towers� foundation covers an important part of the initial cost and its configuration depends heavily on the type of subsoil. Onshore structures are founded on spread footing foundations or pile foundations with the first being the commonest. In these spread footing foundations, the tower is either embedded in the concrete foundation slab or the tower bottom flange is anchored to the concrete by means of pretensioned bolts. This anchoring of the steel tower on the concrete foundation is very rarely analyzed separately and recent failures due to inadequate design have alerted the wind industry towards the solution of the problem. For the purposes of the analytical and numerical approaches, two alternative types of foundation dimensioning are investigated. The tower properties of the two configurations are the same, providing the same loading and material data. The analytical study of the foundation anchoring is performed with the use of the equivalent ring method and the numerical verification of the two foundation solutions is performed with the use of a detailed micro model. The same micro model is used for the calculation of the fatigue life of the tower bottom joint following the damage accumulation method. In both foundation solutions, the total cross sectional area of the anchor bolts is proved to be the decisive factor for the selection of bolt size and number. The size of the tower bottom diameter plays also an important role on the maximum number and size of bolts used. Both analytical and numerical results are in good agreement and valuable outcomes are emerging from the comparative study on the foundation dimensioning of contemporary structures....
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