Current Issue : October - December Volume : 2018 Issue Number : 4 Articles : 5 Articles
An experimental study was conducted to investigate the behavior of composite\nconcrete beams damaged and cracked under pure torsion, and then repaired\nby external strengthening. This was achieved using high strength Carbon\nFiber Reinforced Polymer (CFRP) laminates bonded with epoxy four\ncomposite modify reactive powder concrete (MRPC) I-beams. Different types\nof section (Solid & with opening) were tested to obtain the effect of amount of\nCFRP laminate on beams ultimate torque behavior, angle of twist and failure\nmodes. The results obtained showed that a significant effect of external high\nstrength CFRP laminates on effectively restore of section solid, the range of\n89.8% to 91.2% of ultimate torsional strength effectively restored as well as effectively\nrestoring of section opening by 83.48% - 86.67% of ultimate torsional\nstrength. The repaired beams give high efficiency in ultimate torsional\nstrength, and indicate that the adopted technique gives a good torsional\nstrength....
The mechanical, mesodamage, and the microproperties of cement-emulsified asphalt concrete have been investigated by\ncomputed tomography (CT), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis\n(TG) in this work. Emulsified asphalt delayed the hydration of cement, making the early compressive strength of concrete develop\nslowly. However, the concrete compressive strength increased rapidly with the demulsification of emulsified asphalt. The damage\nstages of condense, expansion of volume, rapid crack propagation, and damage by real-time scanning have been observed. The CT\nmean value of the place near the lower end face suffered a larger decline but a smaller decline to the upper part of the sample. The\nevolution of concrete suffering damage to failure is a gradual development process, and no sharp expansion of brittle failure. The\nunhydrated cement, incorporation asphalt, fibrous Cââ?¬â??Sââ?¬â??H gel, CH, needle-shaped ettringite, and other hydration products were\ninterwoven to constitute emulsified asphalt-cement paste, forming a spatial structure....
A case study of monitoring and analysis of ground settlement caused by tunnelling of stacked twin tunnels for underground metro\nline construction through the densely populated area using the slurry pressure-balanced TBM is presented. Detailed ground\nsettlement monitoring was carried out for the initial stage of down-track tunnelling in order to estimate trough width factor and\nvolume losses including face, shield, and tail losses. In addition, using the gap model, prediction of volume loss and ground\nsettlement was carried out with consideration of the ground condition, TBM configurations, and actual operation data. The\npredictions of the gap model were compared with the observed results, and adjustment factors were determined for volume loss\nestimation. The adjusted factors were applied to predict ground settlement of the up-track tunnel, and its results were compared\nwith the field measurements....
This study is focused on nonlinear analysis and design of spatial and perimeter\nmoment resisting frames for a 9-storeys office building having 9.15 m\nspan. Seismic design criteria of Eurocode 8 Ductility Class High (DCH) with\nbehavior factor (q) of 6.5 and AISC/ASCE code, Special Moment resisting\nFrame (SMF) with response modification factor (R) of 8 were employed. The\ndesign outcomes are expressed in terms of frame performance (non-linear\nanalysis), section profiles (code recommendations), strength-demand to capacity\nratios, drift-demand to capacity ratios and structural weight. The consequences\nof the research compare two codes in term of weights and design\nperformances. This will aid professional engineers and researchers to select\neffective design criteria and capacity design rules efficiently....
In recent years, the development and application of high performance fiber\nreinforced concrete or cementitious composites are increasing due to their\nhigh ductility and energy absorption characteristics. However, it is difficult to\nobtain the required properties of the FRCC by simply adding fiber to the concrete\nmatrix. Many researchers are paying attention to fiber reinforced polymers\n(FRP) for the reinforcement of construction structures because of their\nsignificant advantages over high strain rates. However, the actual FRP products\nare skill-dependent, and the quality may not be uniform. Therefore, in\nthis study, two-way punching tests were carried out to evaluate the performances\nof FRP strengthened and steel and polyvinyl alcohol (PVA) fiber\nreinforced concrete specimens for impact and static loads. The FRP reinforced\nnormal concrete (NC), steel fiber reinforced concrete (SFRC), and PVA FRCC\nspecimens showed twice the amount of enhanced dissipated energy (total\nenergy) under impact loadings than the non-retrofitted specimens. In the\nlow-velocity impact test of the two-way NC specimens strengthened by FRPs,\nthe total dissipated energy increased by 4 to 5 times greater than the plain NC\nseries. For the two-way specimens, the total energy increased by 217% between\nthe non-retrofitted SFRC and NC specimens. The total dissipated\nenergy of the CFRP retrofitted SFRC was twice greater than that of the plain\nSFRC series. The PVA FRCC specimens showed 4 times greater dissipated\nenergy than for the energy of the plain NC specimens. For the penetration of\ntwo-way specimens with fibers, the Hughes formula considering the tensile\nstrength of concrete was a better predictor than other empirical formulae....
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