Enhancement of Load Carrying Capacity of Steel Tubular Columns In-filled with Fibre Reinforced Concrete

2019 ◽  
Vol 23 (4) ◽  
pp. 1711-1721
Author(s):  
Dr. Mohanraj E.K.
Author(s):  
Paolo Foraboschi

Renovation, restoration, remodeling, refurbishment, and retrofitting of build-ings often imply modifying the behavior of the structural system. Modification sometimes includes applying forces (i.e., concentrated loads) to beams that before were subjected to distributed loads only. For a reinforced concrete structure, the new condition causes a beam to bear a concentrated load with the crack pattern that was produced by the distributed loads that acted in the past. If the concentrated load is applied at or near the beam’s midspan, the new shear demand reaches the maximum around the midspan. But around the midspan, the cracks are vertical or quasi-vertical, and no inclined bar is present. So, the actual shear capacity around the midspan not only is low, but also can be substantially lower than the new demand. In order to bring the beam capacity up to the demand, fiber-reinforced-polymer composites can be used. This paper presents a design method to increase the concentrated load-carrying capacity of reinforced concrete beams whose load distribution has to be changed from distributed to concentrated, and an analytical model to pre-dict the concentrated load-carrying capacity of a beam in the strengthened state.


2015 ◽  
Vol 2 (1) ◽  
Author(s):  
N. Aravind ◽  
Amiya K. Samanta ◽  
Dilip Kr. Singha Roy ◽  
Joseph V. Thanikal

AbstractStrengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.


2021 ◽  
Author(s):  
Anil K. Kar

Reinforced concrete is the number one medium of construction. It is important to have good quality concrete and reinforcing bar (rebar). It is equally important to have competent bond between rebar and concrete. About six decades ago ribbed rebars of high strength steel started replacing plain round bars of mild steel, the use of which had made reinforced concrete constructions durable. It was overlooked that ribbed rebars of carbon steel would be highly susceptible to corrosion at accelerated rates. That would not only make reinforced concrete constructions reach states of distress early, that could also destroy or reduce bond between ribbed rebars and concrete. The continued use of ribbed rebars of high strength carbon steel demonstrates a widespread lack of understanding of the phenomenon of bond between rebars and concrete. This lack of understanding of bond has led to the introduction of epoxy coated ribbed rebars, ribbed stainless steel bars and glass fiber reinforced and granite reinforced polymer rebars, all of which permit reinforced concrete carry static loads because of engagement between such rebars and concrete. But the load-carrying capacity of reinforced concrete elements is impaired, and such elements become vulnerable to local or even total failure during vibratory loads. The use of PSWC-BAR, characterized by its plain surface and wave-type configuration, permits the use of medium strength and high strength steel. In the absence of ribs, the rate of corrosion is greatly reduced. The use of PSWC-BARs, at no added effort or cost, in lieu of conventional ribbed bars, leads to enhancement of effective bond or engagement between such rebars and concrete, thereby leading to increased load-carrying capacity, several-fold higher life span, ductility and energy-absorbing capacity, and great reduction in life cycle cost and adverse impact of construction on the environment and the global climate. In keeping with a lack of understanding of bond between rebars and concrete, there is arbitrariness in the selection of the required level of percent elongation and ductility of rebars.


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