Vulnerability Assessment of Reinforced Concrete Framed Structures Considering the Effect of Structural Characteristics

Considering the effects of earthquakes occurred during the last 15 years, this article focusses on finding solutions to minimize the human and economic losses. Several methodologies were developed in order to assess the vulnerability of the built environment with special reference to one of the most suitable structural systems in seismic areas for dwellings, offices or other functionalities, which is the reinforced concrete framed structure. Thus, the present article studies the influence on the vulnerability of reinforced concrete framed structures of geometric structural characteristics like the slab thickness, the building height and the plan configuration. Referring to the slab, it adds supplementary stiffness to the structure that can significantly influence upon its overall failure mechanism. 3D static nonlinear analyses are conducted by means of the SAP2000 computer program. The results are capacity curves which are used to develop the vulnerability curves. Three thicknesses are considered for the slab: 0.1 cm, 0.12 cm and 0.15 m. Medium and high rise structures are considered, with 4, and 8 levels, respectively, in order to determine the influence of the building height on the vulnerability index. Three plan configurations of the buildings are compared: a square one, a rectangular one and an L shaped one. For all the analyzed cases, the corresponding vulnerability curves are compared. The obtained results reveal that more realistic results for the behavior of the structure can be obtained if special attention is given to the structural characteristics, especially during the conceptual design process

Treatment of bauxite contaminated water at Sungai Pengorak using riverbank filtration system (RBF)

Unregulated and rampant bauxite mining activities in Kuantan, Pahang have been seriously polluted the rivers and oceans nearby Sungai Pengorak and Pantai Pengorak. Commonly, surface water is treated by using conventional water treatment method that involved coagulation, filtration and disinfection process. Due to a higher cost in both construction and chemical usages like alum and chlorine in treating raw water for drinking purpose, therefore, in this study, a more economic and cost-effective alternative water treatment method has been implemented, namely riverbank filtration system (RBF). In this study, a fixed bed column test was conducted to evaluate the treatment efficiency of riverbank in Sungai Pengorak in treating bauxite contaminated water. The riverbank consists of mostly sand and some traces of seashells with a range of size from 7.000mm to 0.063mm. Malaysian Department of Environment Water Quality Index (DOE-WQI) were calculated and classified according to Interim National Water Quality Standards, Malaysia (INWQS). Water Quality Index (WQI) was determined on the basis of nine physico-chemical parameters like pH, colour, turbidity, dissolved oxygen (DO), total dissolved solids (TDS), total suspended solids (TSS), ammoniacal nitrogen (AN), biological oxygen demand (BOD) and chemical oxygen demand (COD). Results shown that, based on WQI and INWQS, the bauxite contaminated water in Sungai Pengorak is classified under Class IV and Class V (i.e. highly polluted) respectively. Data obtained from the WQI for raw water was 49.93. However, the bauxite contaminated water after column filtration test improved significantly to Class I (clean) and 95.65 with respect to WQI. In addition, results from the study also fulfilled the National Drinking Water Quality Standards (NDWQS). This study shown that the riverbank can be effectively and economically been used as a safe alternative to treat bauxite contaminated water

Vulnerability and risk evaluation for a reinforced concrete frame

Vulnerability and risk assessment can be evaluated in a deterministic or a probabilistic way and this paper makes a comparison between the two approaches. A 2-D reinforced concrete frame, design according to the Romanian norm, was studied. Starting from the capacity curve obtained with a static non-linear analysis, fragility curves were ploted and an average damage index for the performance point of the structure was calculated. In the probabilistic approach the influence of uncertainties in the damage states thresholds is investigated on fragility and vulnerability curves. The obtained results for two coefficients of variation of the damage states thresholds simulated as random variables, meaning 10% and 20%, are also compared. The used procedures are based on the capacity spectrum method and on Monte Carlo simulations.Postprint (published version

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

ASSESSMENT OF THE DYNAMIC PROPERTIES OF PLAIN AND RUBBERIZED CONCRETE

The use of rubber from discarded car tires as an alternative to natural aggregates in concrete may help preventing the complete depletion of natural resources and work towards a sustainable future. Moreover it can significantly reduce the environmental footprint of the construction industry. The assessment of the dynamic properties of a material are very important from the point of view of the energy dissipation capability of the investigated material. This can be determined from the dynamic modulus of elasticity, damping and the loss coefficients of the material. The paper presents the results obtained during an experimental program aimed at assessing the dynamic characteristics of plain and rubberized concrete containing rubber crumbs from discarded car tires. The theoretical background and the investigation methodology are presented with particular application to cylindrical concrete specimens

Guide to the performance of building structures

SIGLEAvailable from British Library Lending Division - LD:85/14049(Guide) / BLDSC - British Library Document Supply CentreGBUnited Kingdo