Fire resistance of earthquake damaged reinforced concrete frames

The topic of structural damage caused by fires following an earthquake (FFE) has been discussed extensively by many researchers for over a decade in order to bring the two fields closer together in the context of performance based structural engineering. Edinburgh University, Heriot-Watt University, Indian Institute of Technology Roorkee (IIT Roorkee) and Indian Institute of Science initiated a collaboration to study this problem under a UK-India Engineering Research Initiative (UKIERI) funded project. The first construction of a single-storey reinforced concrete frame at IIT Roorkee was completed in summer 2011; this is known as the Roorkee Frame Test 1 throughout this thesis. This thesis presents the modelling of the Roorkee Frame Test 1 using the finite element method and assesses the capability of the numerical methodologies for analysing these two sequential events. Both two and three dimensional finite element models were developed. Beam and shell elements were chosen for the numerical modelling, which was carried out using the general purpose finite element package ABAQUS (version 6.8). The variation in material properties caused by these two types of loading, including strength and stiffness degradation, compressive hardening, tension stiffening, and thermal properties, is implemented in the numerical modelling. Constitutive material calculations are in accordance with EC4 Part 1.1, and all loading is according to IS 1893:2002 Part 1 (Indian Standard). The time-temperature curve used in the analysis is based on data from the test carried out. The behaviour of the Roorkee Frame Test 1 when subjected to monotonic, cyclic lateral loading followed by fire is presented. The capacity of the frame when subjected to lateral loading is examined using a static non-linear pushover method. Incremental lateral loading is applied in a displacement-controlled manner to induce simulated seismic damage in the frame. The capacity curve, hysteresis loops and residual displacements are presented, discussed and compared with the test results. The heat transfer analysis using three dimensional solid elements was also compared against temperature distributions recorded during the Roorkee frame fire test. Based on the smoke layer theory, two emissivity values were defined. In this study, the suitability of numerical modelling using ABAQUS to capture the behaviour of Roorkee frame test is examined. The results from this study show that the 3D ABAQUS model predicted more reliable hysteresis curves compared to the 2D ABAQUS model, but both models estimated the lateral load capacity well. However neither model was able to simulate the pinching effect clearly visible in the hysteresis curves from the test. This was due to noninclusion of the bond slip effect between reinforcing bars and concrete. The residual displacement obtained at the end of the cyclic lateral loading analysis from the 2D ABAQUS model is higher than that seen in the test. However, the result in the 3D ABAQUS model matched the trend obtained in the test. The both columns appear to stiffen under the heating and the residual displacement seems to recover slightly. Lateral displacements, obtained in the thermo-mechanical analysis of the numerical models, show that thermal expansion brings the frame back towards its initial position. Finally, correlation studies between analytical and experimental results are conducted with the objective to establish the validity of the proposed model and identify the significance of various effects on the local and global response of fire resistance earthquake damaged of reinforced concrete frames. These studies show that the effect of tension stiffening and bond-slip are very important and should always be included in finite element models of the response of reinforced concrete frame with the smeared crack model when subjected to lateral and thermal loading. The behaviour of reinforced concrete frames exposed to fire is usually described in terms of the concept of the fire resistance which defined in terms of displacement limit. This study shows the global displacement of the frame subjected to fire recover slightly due to the thermal expansion during the heating

Finite element modelling of compartment fire using ABAQUS

This paper presents finite element modelling (FEM) of a reinforced concrete (RC) frame subjected to elevated temperature. The work presented is part of the UK-India Education and Research Initiative (UKIERI) project. In this project, an experimental test of sub-assemblage frame with elevated temperature has been performed at Indian Institute of Technology (IIT) Roorkee, India. The finite element model using ABAQUS software has been used to validate the increased in temperature distribution on reinforced concrete frame exposed to fire. The idea of this study is to design a compartment fire, and determination of emissivity value at different height. And composition of hot gases was calculated. Gas temperatures used was based on the average temperature-curve obtained in the fire test. The validity of the finite element model was established by comparing the predicted values from the FEM with test data direct from fire test results. The results obtained indicate that suggested FEM analysis procedure is capable of modelling temperature in compartment fire

Experimental investigation on temperature distribution of foamed concrete filled steel tube column under standard fire

Standard fire test was carried out on 3 hollow steel tube and 6 foamed concrete filled steel tube columns. Temperature distribution on the columns was investigated. 1500 kg/m3 and 1800 kg/m3 foamed concrete density at 15%, 20% and 25% load level are the parameters considered. The columns investigated were 2400 mm long, 139.7 mm outer diameter and 6 mm steel tube thickness. The result shows that foamed concrete filled steel tube columns has the highest fire resistance of 43 minutes at 15% load level and low critical temperature of 671 °C at 25% load level using 1500 kg/m3 foamed concrete density. Fire resistance of foamed concrete filled column increases with lower foamed concrete strength. Foamed concrete can be used to provide more fire resistance to hollow steel column or to replace normal weight concrete in concrete filled columns. Since filling hollow steel with foamed concrete produce column with high fire resistance than unfilled hollow steel column. Therefore normal weight concrete can be substituted with foamed concrete in concrete filled column, it will reduces the self-weight of the structure because of its light weight at the same time providing the desired fire resistanc

Exploring the pattern of platoon dispersion caused by traffic signal

Platoon dispersion is an essential phenomenon to be studied for determining the traffic arrivals at downstream intersections to access the need for signal coordination and to optimize the signal timing plans in coordinated signal systems. However, platoon dispersion is difficult to determine compared with other traffic flow parameters such as traffic volume, saturation flow, and speed. This paper explores the pattern of platoon dispersion caused by traffic signal, in which the focus are given on vehicle headway, intra-platoon headway and inter-platoon headway. Field investigation was made by means of videotapes which record traffic flows at selected location at Senai, Johor. After processing the data, vehicle headway at several consecutive points downstream of traffic signal were obtained and used for the platoon dispersion analysis. The dispersion patterns obtained from the observation during peak and off-peak periods were fitted with the theoretical distribution models. It was observed that vehicle headways follow the Erlang and Shifted Negative Exponential Distribution, intra-platoon headways have Normal Distribution and inter-platoon headways do not fit the tested distribution model

Mechanical properties of lightweight concrete using palm oil clinker: an overview

The use of industrial waste as construction material to build environmentally sustainable structure has several practical and economic advantages. Palm oil clinker is a waste material obtained by burning off solid wastes during the process of palm oil extraction. The research performed over the last two decades concerning the use of palm oil clinker as lightweight aggregates concrete is summarized in this paper. A series of concrete mixes were studied and analysed in replacing the coarse and fine aggregates by palm oil clinker. The mechanical properties of the palm oil clinker lightweight concrete are addressed and discussed. The specific gravity for the palm oil clinker must be less than the normal weight aggregate which is below 2.20. The parameters of mechanical properties were reviewed included compressive strength, tensile strength (flexural and splitting) and Young’s modulus. The review showed the positive impact in concrete properties when replaced the normal coarse and fine aggregates with the palm oil clinker. The range of compressive strength of the palm oil clinker lightweight concrete was 30 to 44 MPa. This indicates that palm oil clinker concrete has potential for a replacement which helps in producing a sustainable environment thus contributing to effective construction cost

Mechanical properties of concrete contains waste tires exposed to high temperature

Concrete contains crumb rubber and steel fiber from waste tires has recently gained interest among researchers as an alternative material to be used in the construction field. Mechanical properties of the concrete containing crumb rubber replacement and steel fiber at high temperature was investigated experimentally. The waste crumb rubber was chemically treated by using sodium hydroxide (NaOH). Water cement ratio of Treated Rubberized Steel Fiber Concrete (TRSF-Con) was modified to get similar strength as Normal Concrete (NC). A microstructure analysis using Scanning Electron Microscopy (SEM) test was conducted to investigate the bonding of crumb rubber in the concrete mix at ambient and high temperature. The TRSF-Con has performed satisfactory on reducing the growth and crack width compared with normal concrete when exposed to high temperature. The concrete containing crumb rubber and steel fiber have high potential to be utilized as insulating or reinforcement materials for non-structural composite member, which ensure the elements of the structure will not collapse for a prescribe period of time

Performance of Rubberized Concrete-filled Hollow Steel Column under Monotonic and Cyclic Loadings

Concrete-filled hollow steel (CFHS) has become more popular due to its advantages and benefits compared to reinforced concrete. This paper presents the experimental investigation on the performance of rubberized pozzolanic concrete-filled hollow steel column (RuPCFHS) under monotonic and cyclic lateral load in comparison to bare hollow steel column and normal concrete-filled hollow steel column (NCFHS). The test parameters included the type of concrete infill and the level of axial load. Modified rubberized pozzolanic concrete with comparable compressive strength to that of normal concrete was used. Two types of axial load conditions: no axial load and 20% axial load were considered in the testing. The test results indicate that the performance of the columns improved when concrete infill was introduced in the hollow steel. The application of axial loading also increased the capacity of the column specimens. RuPCFHS behaved with comparable performance with NCFHS in both monotonic and cyclic testing. RuPCFHS recorded the highest increment in the energy dissipation capability when 20% axial load was applied to the column when compared to the other specimens. The comparable performance indicated the possibility of RuPC as an infill material of CFHS and RuPCFHS as a structural component

Behaviour of treated rubberised fiber concretes at higher temperatures

The fundamental aim of this study is to determine the effect of high temperature on the behavior of concrete consists NaOH treated rubber and steel fibers (TRSF-Con). During the experiment, four different concrete mixes were prepared; the first one is the control mix (CM) which was made with natural coarse and fine aggregates, cement, and water, while the other three concrete mixes were with the replacement rates of 10%, 20% and 25% of the natural coarse and fine aggregates by TRSF from used tires. The specimens were exposed for a period of 1 hour to design temperature-time curve up to 800°C followed by cooling to room temperature. Compressive strength, flexural strength, weight loss were determined and compared with that of control specimens. The ductility of the concrete increased with the increased of TRSF contents, increases the damping properties, and while the compressive strength of the concrete reduced with the increment of TRSF contents. Although data obtained in all parameters where lover than the control specimens, concrete containing treated rubber and steel fiber can be suitable for non-structural member in concrete and driveways or road constructions

The thermal response of multi-storeies concrete frame building in the Arabic area

In this paper, there will be an analysis study to figure out the impact of the environment thermal loads, shrinkage and creep at multi-storeies reinforced concrete frame buildings in the Arabic area. Etabs models will be prepared considering time dependent properties of concrete and non-time dependent properties, considering two columns heights as 3m and 6m, and two supports conditions as fixed and hinged to define the major aspects affect the thermal response of multi-storey concrete frame buildings concentrating at the thermal deformations and the columns reactions, then it will be compared with the thermal response of existing concrete building considering both methodologies of time dependent properties and non-time dependent properties of concrete to define the optimum methodology to be recommended and followed The generated Etabs models confirmed that the time dependent properties method is the optimum with a clear conversion between time dependent properties model and the existing parking thermal deformations. The increment in horizontal reactions under thermal loads due to column support condition is accompanied with a reduction in horizontal slabs deformations. Column height is inversely proportional to horizontal reaction values, finally, the importance of analyzing thermal loads fluctuation at columns reactions for multi storeies buildings whereas the reactions of multi storeies cannot be predicted from single storey analysis