Behaviour of short columns made with conventional or FRP-confined rubberised concrete : an experimental and numerical investigation

Failure of short columns in concrete buildings has been extensively reported during past earthquakes. Assessing the behaviour of short columns is challenging and often requires using time-consuming advanced numerical modelling. This article presents a new and practical Short Column Macro Element (SCME) that predicts accurately the behaviour of concrete short columns. A 1/3-scale one-storey building with short columns is subjected to lateral loading tests until failure. The experimental results from the building are then used to calibrate a numerical model in Abaqus®. It is shown that the numerical model matches well the experimental results. The experimental crack patterns and stress distribution from Abaqus® are then used to determine the load path within the short column. Based on these data, a new strut-and-tie SCME is proposed and implemented in OpenSees software to simulate accurately (within 5% accuracy) the behaviour of the short columns of the tested building. Subsequently, the frame models calibrated in OpenSees and Abaqus® are modified to examine numerically the effectiveness of highly deformable FRP-confined rubberised concrete (FRP CRuC) at increasing the deformability of short columns with different levels of FRP confinement (1, 2 or 3 layers). The numerical results show that whilst the tested building failed at a small displacement of 5.4 mm (0.43% drift ratio), the use of FRP CRuC short columns with minimal confinement (1 layer of AFRP only) increased the building’s displacement by almost seven times to 37 mm (3.0% drift ratio). This also enabled more redistribution of forces to other structural members of the building. This article contributes towards the development of practical design/analysis models for short columns made of conventional concrete and FRP CRuC, which are scarce in the existing literature

Full-Scale Shaking Table Tests on a Substandard RC Building Repaired and Strengthened with Post-Tensioned Metal Straps

The effectiveness of a novel Post-Tensioned Metal Strapping (PTMS) technique at enhancing the seismic behaviour of a substandard RC building was investigated through full-scale shake-table tests during the EU-funded project BANDIT. The building had inadequate reinforcement detailing in columns and joints to replicate old construction practices. After the bare building was initially damaged significantly, it was repaired and strengthened with PTMS to perform additional seismic tests. The PTMS technique improved considerably the seismic performance of the tested building. Whilst the bare building experienced critical damage at an earthquake of PGA=0.15g, the PTMS-strengthened building sustained a PGA=0.35g earthquake without compromising stability

Environmental LCA of innovative reuse of all End-of-life tyre components in concrete

This paper presents the environmental life-cycle assessment of concrete mixtures containing materials recycled from End-of-Life tyres, i.e. rubber particles, sorted steel wires and polymer/textile cord fibres. This life-cycle assessment is based on ILCD and the ISO standards and considers “cradle to gate”, i.e. from extraction of raw materials, tyre-recycling and up to concrete production in ready mixture concrete plants. In total, 21 different concrete mixtures were analysed, including rubberised concrete and fibre reinforced concrete; mixtures with hybrid fibres were also considered (i.e. reinforced with both recycled and manufactured fibres). The results of this LCA show that, for a functional unit of 1 m3 of concrete, cement is the main parameter contributing to the inventory of the examined concrete mixtures; this indicates the need of utilising “low energy” and low calcination cements to minimise their environmental impact. When performance-based functional units are considered in the LCA, the results highlight the importance of using these recycled materials in structural concrete applications that fully utilise the specific mechanical characteristics of each material, as demonstrated for rubberised concrete and steel fibre-reinforced concrete mixtures

Use of Finite Elements Analysis for a Weigh-in-Motion Sensor Design<em></em>

High speed weigh-in-motion (WIM) sensors are utilized as components of complex traffic monitoring and measurement systems. They should be able to determine the weights on wheels, axles and vehicle gross weights, and to help the classification of vehicles (depending on the number of axles). WIM sensors must meet the following main requirements: good accuracy, high endurance, low price and easy installation in the road structure. It is not advisable to use cheap materials in constructing these devices for lower prices, since the sensors are normally working in harsh environmental conditions such as temperatures between –40 °C and +70 °C, dust, temporary water immersion, shocks and vibrations. Consequently, less expensive manufacturing technologies are recommended. Because the installation cost in the road structure is high and proportional to the WIM sensor cross section (especially with its thickness), the device needs to be made as flat as possible. The WIM sensor model presented and analyzed in this paper uses a spring element equipped with strain gages. Using Finite Element Analysis (FEA), the authors have attempted to obtain a more sensitive, reliable, lower profile and overall cheaper elastic element for a new WIM sensor

Interspecies gene name extrapolation - A new approach

The use of animal models has facilitated numerous scientific developments, especially when employing "omics" technologies to study the effects of various environmental factors on humans. Our study presents a new bioinformatics pipeline suitable when the generated microarray data from animal models does not contain the necessary human gene name annotation. We conducted single color gene expression microarray on duodenum and spleen tissue obtained from pigs which have been exposed to zearalenone and Escherichia coli contamination, either alone or combined. By performing a combination of file format modifications and data alignments using various online tools as well as a command line environment, we performed the pig to human gene name extrapolation with an average yield of 58.34%, compared to 3.64% when applying more simple methods. In conclusion, while online data analysis portals on their own are of great importance in data management and assessment, our new pipeline provided a more effective approach for a situation which can be frequently encountered by researchers in the "omics" era

Shake Table Tests on Deficient RC Buildings Strengthened Using Post-Tensioned Metal Straps

The European research project BANDIT investigated the effectiveness of a novel Post-Tensioned Metal Strapping (PTMS) strengthening technique at improving the seismic performance of deficient RC buildings using shake table tests. A full-scale two-story structure was designed with inadequate reinforcement detailing of columns and beam-column joints so as to simulate typical deficient buildings in Mediterranean and developing countries. Initial shaking table tests were carried out until significant damage was observed in the beam-column joints of the bare frame. Subsequently, the damaged building was repaired and strengthened using PTMS and additional tests were performed. The results of this study show that the adopted strengthening strategy improved significantly the seismic performance of the substandard RC building under strong earthquake excitations

Sample distribution and types of treatment used in the experiment.

<p>Sample distribution and types of treatment used in the experiment.</p

Contribution numérique pour l’optimisation d’un mode opératoire de soudage – Identification d’une source de chaleur équivalente

The effectiveness of a novel Post-Tensioned Metal Strapping (PTMS) technique at enhancing the seismic behavior of a substandard RC building was investigated through full-scale, shake-table tests during the EU-funded project BANDIT. The building had inadequate reinforcement detailing in columns and joints to replicate old construction practices. After the bare building was initially damaged significantly, it was repaired and strengthened with PTMS to perform additional seismic tests. The PTMS technique improved considerably the seismic performance of the tested building. While the bare building experienced critical damage at an earthquake of PGA = 0.15 g, the PTMS-strengthened building sustained a PGA = 0.35 g earthquake without compromising stability