Constant exposure to traffic noise pollution can have significant impact on human health and well being. Occupants of high-rise buildings along noisy traffic arteries are severely affected. In an attempt to contribute to noise protection design of prospective high-rise buildings, traffic noise measurements and prediction using the CRTN (calculation of road traffic noise) model, were made along the façade of a high-rise building in central Athens. The aim was to test the accuracy of this model in predicting the vertical distribution (mapping) of traffic noise along such building façades, under the local urban characteristics of the Mediterranean capital. The predicted and measured noise levels were found to be highly coherent with each other, and their vertical distribution pattern, by and large, confirmed findings from earlier studies. Nevertheless, the predicted values had a tendency of underestimation, with a mean difference −2.2 dB(A) with reference to measured values. It is considered that this underestimation is associated mainly with a newly proposed feature of urban morphology, namely (local) geo-morphology. By and large, it can be inferred that the CRTN model is a useful tool, suitable for the prediction of traffic noise along high-rise building façades during their planning and design stage. The results represent a further step towards more general application of this model, as well as a contribution to the use of this model considering a wider number of urban features.
Abstract:The tensile behavior of concrete or mortar plays an important role for delaying the formation and propagation of cracks, and also for upgrading the bearing capacity of existing concrete and masonry constructions. Although the presence of steel fibers is known to improve, often considerably, the tensile capacity of concrete members, methods for the quantification of this improvement are still limited. For this reason, a model has been developed for the prediction of the tensile strength of steel fiber-reinforced concrete members, as crack opening occurs. Given the geometry and the physical characteristics of reinforced concrete member and fibers, the model predicts: (1) the number of fibers crossing a crack's surface; (2) the distribution of these fibers in terms of (i) the angle a fiber forms with the crack surface (fiber inclination) and (ii) the embedded length of the fiber at both sides of the surface; (3) resistance to crack opening provided by each fiber, in relation to its position and inclination. On the results of the results obtained, the influence of the number of fibers on the reduction of crack widening in concrete or mortar is remarkable and can be estimated with satisfactory precision. In upgrading existing concrete and masonry constructions, this tensile behavior is found to play important role.
This work forms part of a research programme to assess and strengthen existing reinforced concrete (RC) walls that were designed using older seismic codes. The main object of the present paper is to examine the behaviour of concrete shear walls that do not comply with modern seismic codes (Eurocode 2 (EC2) and Eurocode 8 (EC8)) andcompare their experimental performance with the provisions for assessment of RC members included in EC8 Part 3. For this purpose, a series of six shear walls (height h 1 . 40 m, length l 0 . 74 m, thickness b 0 . 10 m) was designed and tested under static cyclic loading. The wall specimens were characterised by various types of reinforcement arrangement, focusing on different amounts of shear reinforcement. The issues investigated are the failure modes, ductility level, the absence of confined boundary elements, the low amount of shear reinforcement, the influence of diagonal reinforcement and the influence of axial load. The experimental results are compared with the provisions included in EC8 Part 3, which predict the shear strength, the chord rotation ductility and the effective stiffness of RC shear walls.
The use of additional bars, internally placed through drill holes, in external beam-column connections subjected to cyclic loading, as shear reinforcement is experimentally investigated.The presented experimental work includes tests of full-scale specimens with different reinforcement arrangements in the joint area, they are as follows: (a) the JB0V control specimen with two (extra) vertical side bars without shear reinforcement in the joint area and, (b) the JB0R joint, same as in the case of the control specimen, without the extra vertical bars, but with four additional steel bars that were placed in holes, which were drilled through the concrete of the joint body for this purpose, (c) the JB0VFX joint, the damaged control specimen repaired and strengthened with C-FRP diagonal ties (rope connections) through the joint area. The effectiveness of these additional bars and ropes as a shear reinforcement on the overall seismic performance of the tested joint is examined.A comparison between the test results of the examined specimens indicated that the applied retrofitting technique is appropriate for the enhancement of the overall hysteretic performance of the beam-column joints in terms of load carrying capacity, stiffness and hysteretic energy dissipation.
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