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This paper presents a review of current knowledge on the bond behavior of fiber reinforced polymer (FRP) systems inserted in the cover of concrete elements, commonly known as the near-surface mounted technique (NSM). In the first part, by studying the physics of the phenomenon, the typical failure modes, the most common bond tests and two of the most important design guidelines for FRP NSM systems are introduced. In the second part, a database of bond tests composed by 431 records is presented and the accuracy of existing design guidelines is assessed with this data. Lastly, the formulations proposed by these design guidelines are recalibrated based on the experimental results in the database.Keywords: FRP; NSM; Bond; Review grooves have vertical and parallel sides, square and rectangular bars explore better this grooves' geometry since a more uniform adhesive thickness is achieved. Moreover, with the use of round bars, split of the groove filling cover may occur due to the existing stresses perpendicular to the FRP. In the case of square and rectangular bars this normal stress component acts mainly towards the groove lateral concrete.Comparing square and rectangular bars, the latter maximize the ratio of surface to cross-section area, minimizing the bond stresses for the same tensile force in the FRP. Other advantage of using 3 rectangular bars is related with the simplicity of opening the grooves: a single saw cut is normally enough for obtaining the groove while with round/square bars two saw cuts and removal of the concrete in between are usually required. The main disadvantage of rectangular bars is the need for a deeper groove to provide the same reinforcement area.In terms of the adhesives used to bond FRP bars to concrete, epoxy adhesives are the most common, even though some researchers have used cement mortar [4,5]. In general, cement based adhesives have lower mechanical strength and higher curing time. On the other hand, they present better performance when subjected to high temperatures.The most recent comprehensive review on the NSM technique was published in 2007 [6]. In order to provide a wider overview of the technique, it was not focused on the bond. Moreover, since then, a manifold of experimental works focusing on bond performance of FRP NSM systems have been developed. Hence, the scope of this work is to provide a review on the bond behavior of FRP NSM systems in concrete. This review includes, in the first part, an introduction to the typical observed failure modes, the most commonly used bond tests and two of the most important design guidelines. In the second part of this paper, a database of 431 bond tests is presented, the accuracy of the design guidelines is tested and several modifications to these guidelines' formulations are proposed. FRP NSM technique Failure modes at structural levelConsidering a reinforced concrete element strengthened in bending (and/or shear) with a FRP NSM system, six failure modes combining different stress states on the three intervening materials (concrete, ...

SUMMARYThis paper presents an analytical study evaluating the influence of ground motion duration on structural damage of 3-story, 9-story, and 20-story SAC steel moment resisting frame buildings designed for downtown Seattle, WA, USA, using pre-Northridge codes. Two-dimensional nonlinear finite element models of the buildings are used to estimate the damage induced by the ground motions. A set of 44 ground motions is used to study the combined effect of spectral acceleration and ground motion significant duration on drift and damage measures. In addition, 10 spectrally equivalent short-duration shallow crustal ground motions and long-duration subduction zone records are selected to isolate duration effect and assess its effect on the response. For each ground motion pair, incremental dynamic analyses are performed at at least 20 intensity levels and response measures such as peak interstory drift ratio and energy dissipated are tracked. These response measures are combined into two damage metrics that account for the ductility and energy dissipation. Results indicate that the duration of the ground motion influences, above all, the combined damage measures, although some effect on drift-based response measures is also observed for larger levels of drift. These results indicate that because the current assessment methodologies do not capture the effects of ground motion duration, both performance-based and code-based assessment methodologies should be revised to consider damage measures that are sensitive to duration.

-This paper presents the application of three Machine Learning techniques to fuel consumption modelling of articulated trucks for a large dataset. In particular, Support Vector Machine (SVM), Random Forest (RF), and Artificial Neural Network (ANN) models have been developed for the purpose and their performance compared. Fleet managers use telematic data to monitor the performance of their fleets and take decisions regarding maintenance of the vehicles and training of their drivers. The data, which include fuel consumption, are collected by standard sensors (SAE J1939) for modern vehicles. Data regarding the characteristics of the road come from the Highways Agency Pavement Management System (HAPMS) of Highways England, the manager of the strategic road network in the UK. Together, these data can be used to develop a new fuel consumption model, which may help fleet managers in reviewing the existing vehicle routing decisions, based on road geometry. The model would also be useful for road managers to better understand the fuel consumption of road vehicles and the influence of road geometry. Ten-fold cross-validation has been performed to train the SVM, RF, and ANN models. Results of the study shows the feasibility of using telematic data together with the information in HAPMS for the purpose of modelling fuel consumption. The study also shows that although all the three methods make it possible to develop models with good precision, the RF slightly outperforms SVM and ANN giving higher R2, and lower error.

Old timber structures may show significant variation in the cross section geometry along the same element, as a result of both construction methods and deterioration. As consequence, the definition of the geometric parameters in situ may be both time consuming and costly. This work presents the results of inspections carried out in different timber structures. Based on the obtained results, different simplified geometric models are proposed in order to efficiently model the geometry variations found. Probabilistic modelling techniques are also used to define safety parameters of existing timber structures, when subjected to dead and live loads, namely self-weight and wind actions. The parameters of the models have been defined as probabilistic variables, and safety of a selected case study was assessed using the Monte Carlo simulation technique. Assuming a target reliability index, a model was defined for both the residual cross section and the time dependent deterioration evolution. As a consequence, it was possible to compute probabilities of failure and reliability indices, as well as, time evolution deterioration curves for this structure. The results obtained provide a proposal for definition of the cross section geometric parameters of existing timber structures with different levels of decay, using a simplified probabilistic geometry model and considering a remaining capacity factor for the decayed areas. This model can be used for assessing the safety of the structure at present and for predicting future performance.