The present research work aims to investigate numerically the behaviour of steel fibre reinforced concrete beam–column joints under seismic action. Both exterior and interior joint types were examined and 3D nonlinear finite element analyses were carried out using ABAQUS software. The joints were subjected to reversed-cyclic loading, combined with a constant axial force on the column representing gravity loads. The joints were initially calibrated using existing experimental data – to ascertain the validity of the numerical model used – and then parametric studies were carried out using different steel fibre ratios coupled with increased spacing of shear links. The aim was to assess the effect of introducing steel fibres into the concrete mix in order to compensate for a reduced amount of conventional transverse steel reinforcement and hence lessen congestion of the latter. This is particularly useful for joints designed to withstand seismic loading as code requirements (e.g. Eurocode 8) lead to a high amount of shear links provided to protect critical regions. The spacing between shear links was increased by 0%, 50% and 100%, whilst the fibre volume fraction (Vf) was increased by 0%, 1%, 1.5%, 2% and 2.5%. Potential enhancement to ductility, a key requirement in seismic design, was investigated as well as potential improvements to energy absorption and confinement. The work also examined key structural issues such as strength, storey drift, plastic hinges formation and cracking patterns

Congestion is an ongoing problem for many urban centres worldwide (such as London), leading to excessive delays, noise and air pollution, frustrated drivers, and high energy consumption. The carbon footprint of conventional transport systems can be high as a result and transport is among the highest contributors of greenhouse gas emissions. Therefore, with the growing interest in developing connected fully autonomous vehicles (ConFAVs), there is a pressing need to consider their effects within the congested urban setting. To address this, the current research study was designed to investigate the potential for ConFAVs in providing a sustainable transport solution. During this research, a simulation model was developed, calibrated, and validated using field data collected from several sites in East London, using the graphical user interface (GUI) simulation software PTV VISSIM to simulate the proposed driving and car following behaviour, which included the platooning of these ConFAVs, to assess how they could improve the level of service of the roads. Using the new model, this research addresses the shortcomings of two other adaptations of the Wiedemann 99 car-following models by changing the ConFAV’s behaviour to be more cautious when travelling behind a human driven vehicle, and less cautious when behind another ConFAV. As little is known about the transitional period from zero autonomy to full autonomy on the already congested road network, due to the fact that these vehicles are typically tested in small numbers (often one at a time in a controlled environment), the present research study introduced ConFAVs to the simulated network gradually and in large numbers at 20% intervals (namely 0% where there are no ConFAVs, 20%, 40%, 60%, 80%, and finally 100% where all vehicles within the network were ConFAVs). The average delays and subsequent level of service for the roads within the networks were then assessed against each ConFAV penetration level. This helped understand how the network’s efficiency changes when the number of ConFAVs increases, and the potential benefits for these self-driving vehicles on congestion and the ensuing greenhouse gas emissions. The model showed that a reduction in delay of up to 100% can be achieved by introducing ConFAVs, which translates to a significant reduction in greenhouse gas emissions. This, coupled with the fact that ConFAVs are predominantly electric, points to a future sustainable road transport system. The primary purpose of this research would be to investigate the potential of ConFAVs in reducing traffic congestion and, as a result, greenhouse gas emissions.

The present numerical investigation offers evidence concerning the validity and objectivity of the predictions of a simple, yet practical, finite element model concerning the responses of steel fibre reinforced concrete structural elements under static monotonic and cyclic loading. Emphasis is focused on realistically describing the fully brittle tensile behaviour of plain concrete and the contribution of steel fibres on the post-cracking behaviour it exhibits. The good correlation exhibited between the numerical predictions and their experimental counterparts reveals that, despite its simplicity, the subject model is capable of providing realistic predictions concerning the response of steel fibre reinforced concrete structural configurations exhibiting both ductile and brittle modes of failure without requiring recalibration

The structural behaviour of steel-fibre-reinforced concrete beams was studied using non-linear finite-element analysis and existing experimental data. The work aim was to examine the potential of using steel fibres to reduce the amount of conventional transverse steel reinforcement without compromising ductility and strength requirements set out in design codes. To achieve this, the spacing between shear links was increased while steel fibres were added as a substitute. Parametric studies were subsequently carried out and comparisons were also made with BS EN 1992-1-1 predictions. It was concluded that the addition of steel fibres enhanced the load-carrying capacity and also altered the failure mode from a brittle shear mode to a flexural ductile one. The provision of fibres also improved ductility. However, interestingly it was found that adding excessive amounts of fibres led to a less-ductile response. Overall, the study confirmed the potential for fibres to compensate for a reduction in conventional shear reinforcement.

This paper summarises the test data obtained from an experimental investigation of reinforced concrete (RC) wide beams, which can also be described as one-way slabs, under low-rate (static) and high-rate (impact) concentrated loading applied at their mid-span. The aim of the work was to investigate key aspects of structural response such as the load–deformation behaviour, crack patterns, strength and failure modes of these basic structural elements under varying levels of loading rate. Three 125 mm thick specimens were studied and they measured 1800 mm long and 360 mm wide. They were simply supported at a span of 1600 mm. One specimen was tested under static loading, and the other two were subjected to impact loading using a drop weight. For both load rates investigated, measurements included strains, deflections and support reactions. Additional measurements for the impact test included accelerations and the use of a high-speed, high-resolution video camera to record the whole test. Digital photography was also used for the low-rate test. The use of digital photography and video recording has proved to be a valuable source of data to validate the readings of the more conventional instrumentation and also to give insight into transient features of the impact test such as crack patterns, particularly those which opened and closed during the test. The comparison between the low-rate and impact behaviour has helped further the understanding of the structural response of RC structures under varying rates of loading.

An investigation was done into the development of lightweight-aggregate concrete mixes with lower embodied carbon dioxide emissions suitable for structural applications. Production requires the replacement of normal-weight coarse aggregate with a lightweight aggregate. Lytag was considered, which is a good-quality lightweight aggregate manufactured from fly ash. Lightweight-aggregate concrete for structural applications usually contains a high CEM I content owing to the requirements for workability, pumpability and strength. Consequently, its embodied carbon dioxide emissions are generally higher than that of normal-weight concrete. Mixes of LC30/33 class were developed containing up to 60% ground granulated blast-furnace slag, as well as limestone powder, and their fresh and mechanical properties were assessed experimentally. It was found that the embodied carbon dioxide of the investigated mix could be reduced by up to 40% when compared with that of neat CEM I lightweight-aggregate mixes containing Lytag aggregates and to 20% when compared with that of a mix that would be generally used in current practice in the UK containing 40% slag. It was also possible to reduce the CEM I content in the investigated mixes by approximately 40% compared with what would have been normally used.