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1 – 10 of 36This paper aims to study the residual test results under uni-axial compression of tie confined pre-damaged normal strength concrete short columns subjected to elevated…
Abstract
Purpose
This paper aims to study the residual test results under uni-axial compression of tie confined pre-damaged normal strength concrete short columns subjected to elevated temperatures.
Design/methodology/approach
The test variables included temperature of exposure, spacing of transverse confining reinforcement and pre-damage level. An experimental program was designed and carried out involving testing of hoop confined concrete cylindrical specimens exposed to elevated temperatures ranging from room temperature to 900 °C.
Findings
The test results indicate that the residual strength, strain corresponding to the peak stress and the post-peak strains of confined concrete are not affected significantly up to an exposure temperature of 300 °C. However, the peak confined stress falls and the corresponding strain increase considerably in the temperature range of 600 to 900 °C. It is shown that an increase in the degree of confinement reinforcement results in an increased residual strength and deformability of pre-damaged confined concrete.
Research limitations/implications
It is applicable in finding the residual strength and strain of the pre-damaged confined concrete in uni-axial compression after exposure to elevated temperature.
Practical implications
The practical implications is that the test result is applicable in finding the residual strengths of pre-damaged confined concrete under uni-axial compression after exposure to elevated temperature.
Social implications
The main aim of the present investigation is to provide experimental data on the residual behaviour of pre-damaged confined concrete subjected to high temperatures.
Originality/value
The results of this study may be useful for developing the guidelines for designing the confinement reinforcement of reinforced concrete columns against the combined actions of earthquake and fire, as well as for designing the retrofitting schemes after these sequential disasters.
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Umesh Sharma, Virendra Kumar, Praveen Kamath, Bhupinder Singh, Pradeep Bhargava, Yogendra Singh, Asif Usmani, Jose Torero, Martin Gillie and Pankaj Pankaj
In present study, a full-scale testing of reinforced concrete (RC) frame sub-assemblage has been investigated under fire subsequent to simulated seismic loading. First part of the…
Abstract
In present study, a full-scale testing of reinforced concrete (RC) frame sub-assemblage has been investigated under fire subsequent to simulated seismic loading. First part of the sequential loading consisted of a quasi-static cyclic lateral loading corresponds to life safety level of structural performance on the test frame. In the second part of the test, a compartment fire was ignited to the pre-damaged test frame for one hour duration simulating fire following earthquake (FFE) scenario. The results showed that the first cracking was observed at the end joints of the roof beams after the frame experienced a 30 mm cyclic lateral displacement. One hour heating and eleven hour cooling was tracked and temperatures were recorded. A knocking sound was heard from the fire compartment after 5 minutes of the fire ignition. An excessive degradation of the concrete material at a number of locations of the frame sub-assemblage was observed during visual inspection after the fire test. The Nondestructive tests (NDT) were also conducted to ascertain the damage in the RC frame at the various stages of loading. The test results developed an understanding of the behaviour of RC frame sub-assemblage in FFE.
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THE application of cemented wires to determine the location of initial failure in static tests on large specimens has been investigated, among others, by R. W. Powell in 1946.
The occurrence of multiple hazards in extreme conditions is not unknown nowadays, but the sustainability of the reinforced concrete structures under such scenarios form…
Abstract
Purpose
The occurrence of multiple hazards in extreme conditions is not unknown nowadays, but the sustainability of the reinforced concrete structures under such scenarios form competitive challenges in civil engineering profession. Among all, fire following earthquake (FFE) is categorized under multiple extreme load scenarios which causes sequential damages to the structures. This paper aims to experiment a full-scale RC frame sub-assemblage for the FFE scenario and assess each stage of damage through the nondestructive testing method.
Design/methodology/approach
Two levels of simulated earthquake damages, i.e. immediate occupancy (IO) level and life safety (LS) level of structural performance were induced to the test frame and then, followed by a realistic compartment fire of 1 h duration. Also, the evaluation of damage to the RC frame after the fire subsequent to the earthquake was carried out by obtaining the ultimate capacity of the frame. Ultrasonic pulse velocity and rebound hammer test were conducted to assess the structural endurance of the damaged frame. Cracks were also marked during mechanical damages to the test frame to study the nature of its propagation.
Findings
Careful visual inspection during and after the fire test to the test frame were done. To differentiate between concrete chemically affected by the fire or physically damaged is an important issue. In situ inspection and laboratory tests of concrete components have been performed. Concrete from the test frame was localized with thermo-gravimetric analysis. The UPV results exhibited a sharp decrease in the strength of the concrete material which was also confirmed via the DTA, TGA and TG results. It is important to evaluate the residual capacity of the entire structure under the FFE scenario and propose rehabilitation/retrofit schemes for the building structure.
Research limitations/implications
The heterogeneity in the distribution of the damage has been identified due to variation of fire exposure. The study only highlights the capabilities of the methods for finding the residual capacity of the RC frame sub-assemblage after an occurrence of an FFE.
Originality/value
It is of find kind of research work on full-scale reinforced concrete building. In this, an attempt has been made for the evaluation of concrete structures affected by an FFE through nondestructive and destructive methods.
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Nursyamsi Nursyamsi, Johannes Tarigan, Muhammad Aswin, Badorul Hisham Abu Bakar and Harianto Hardjasaputra
Damage to reinforced concrete (RC) structural elements is inevitable. Such damage can be the result of several factors, including aggressive environmental conditions, overloading…
Abstract
Purpose
Damage to reinforced concrete (RC) structural elements is inevitable. Such damage can be the result of several factors, including aggressive environmental conditions, overloading, inadequate design, poor work execution, fire, storm, earthquakes etc. Therefore, repairing and strengthening is one way to improve damaged structures, so that they can be reutilized. In this research, the use of an ultra high-performance fibre-reinforced concrete (UHPFRC) layer is proposed as a strengthening material to rehabilitate damaged-RC beams. Different strengthening schemes pertaining to the structural performance of the retrofitted RC beams due to the flexural load were investigated.
Design/methodology/approach
A total of 13 normal RC beams were prepared. All the beams were subjected to a four-point flexural test. One beam was selected as the control beam and tested to failure, whereas the remaining beams were tested under a load of up to 50% of the ultimate load capacity of the control beam. The damaged beams were then strengthened using a UHPFRC layer with two different schemes; strip-shape and U-shape schemes, before all the beams were tested to failure.
Findings
Based on the test results, the control beam and all strengthened beams failed in the flexural mode. Compared to the control beam, the damaged-RC beams strengthened using the strip-shape scheme provided an increase in the ultimate load capacity ranging from 14.50% to 43.48% (or an increase of 1.1450 to 1.4348 times), whereas for the U-shape scheme beams ranged from 48.70% to 149.37% (or an increase of 1.4870–2.4937 times). The U-shape scheme was more effective in rehabilitating the damaged-RC beams. The UHPFRC mixtures are workable, as well easy to place and cast into the formworks. Furthermore, the damaged-RC beams strengthened using strip-shape scheme and U-shape scheme generated ductility factors of greater than 4 and 3, respectively. According to Eurocode8, these values are suitable for seismically active regions. Therefore, the strengthened damaged-RC beams under this study can quite feasibly be used in such regions.
Research limitations/implications
Observations of crack patterns were not accompanied by measurements of crack widths due to the unavailability of a microcrack meter in the laboratory. The cost of the strengthening system application were not evaluated in this study, so the users should consider wisely related to the application of this method on the constructions.
Practical implications
Rehabilitation of the damaged-RC beams exhibited an adequate structural performance, where all strengthened RC beams fail in the flexural mode, as well as having increment in the failure load capacity and ductility. So, the used strengthening system in this study can be applied for the building construction in the seismic regions.
Social implications
Aside from equipment, application of this strengthening system need also the labours.
Originality/value
The use of sand blasting on the surfaces of the damaged-RC beams, as well as the application of UHPFRC layers of different thicknesses and shapes to strengthen the damaged-RC beams, provides a novel innovation in the strengthening of damaged-RC beams, which can be applicable to either bridge or building constructions.
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Recently, the repairing of reinforced concrete (RC) structures attracted great research attentions, but the research interests were mainly concentrated on common repairing types…
Abstract
Purpose
Recently, the repairing of reinforced concrete (RC) structures attracted great research attentions, but the research interests were mainly concentrated on common repairing types. To this end, in this paper, a repairing of pre-loaded RC beams strengthened by aramid reinforcement polymers (AFRP) is presented. Furthermore, the purpose of this paper is to study the behavior of pre-loaded RC Deep beams under sustained load. The AFRP has many advantages such as controlling stresses distribution around the openings, controlling failure modes, and enhancing the structural capacity of pre-cracked RC beams.
Design/methodology/approach
Four specimens were experimentally tested: one specimen without strengthening, which is considered as control specimen, one strengthened specimen using AFRP without pre-cracking and two specimens subjected to pre-cracking load before prior to AFRP application. Furthermore, after validation of experimental data by using ANSYS software, a parametric study was conducted to investigate the effect of pre-damage level on shear capacity of RC beams. For pre-cracked beams, loading was first applied until the cracking stage, followed by specimen repairing with epoxy injection, and then the specimens were loaded again until failure point.
Findings
The result showed that pre-damage level and AFRP strengthening have great influence on the ultimate strength and failure mode. In addition, the results obtained from experimental tests were compared with those from numerical validation with ANSYS and showed good agreement.
Originality/value
Based on ACI guidelines, an analytical equation for calculating the shear strength of strengthened RC beams with openings subjected to pre-damage was then proposed, and the calculated results were compared with those from the tests, with differences not exceeding 10%.
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The performance for surface coatings for the protection of both offshore structures and submarine pipelines are probably the most stringent of any outside those of space travel.
Focuses on the use of biocides to combat the growth of microorganisms in coolant systems and oils. Outlines measures which can limit or prevent mcrobial growth and provides a…
Abstract
Focuses on the use of biocides to combat the growth of microorganisms in coolant systems and oils. Outlines measures which can limit or prevent mcrobial growth and provides a brief summary of the European Biocidal Products Directive.
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M.T. Copper, W.H. Thomason and J.D.C. Vardon
The development of the Hutton Field in the UK sector of the North Sea incorporates, for the first time, a buoyant Tension Leg Platform maintained in position by an array of…
Abstract
The development of the Hutton Field in the UK sector of the North Sea incorporates, for the first time, a buoyant Tension Leg Platform maintained in position by an array of sixteen tubular steel tension leg strings. To satisfy the stringent design criteria associated with this new generation of offshore oil production facilities, all corrosion control systems have to be effective, reliable and contribute little to structure weight. An intensive review of the various available design options was undertaken, from which emerged the use of aluminium metal sprayed coatings as possibly the optimum method of corrosion control for the tension legs. Since there was limited service data available relating to the performance of sprayed metal coatings in sea water immersion service, a development programme was completed to determine the perfomance characteristics of these coatings under tension leg operating conditions. In parallel, the problems of applying the coatings were addressed since it was considered that, as for all coating systems, correct application is critical to the satisfactory in‐service performance of the coating. The potential advantages of sprayed metal coatings for immersion service in the offshore industry was significant.
All anti‐corrosive coatings have a common role of protecting the substrate to which they are applied.