scholarly journals Effect of Different Lateral Reinforcement and its Spacing on Column Reinforced with Hollow Composite Sections

2021 ◽  
Vol 9 (11) ◽  
pp. 1711-1719
Author(s):  
Sneha Nair M D
Keyword(s):  
High Strength ◽  
Concrete Surface ◽  
Nonlinear Static Analysis ◽  
Structural Behaviour ◽  
Concrete Core ◽  
Gfrp Bars ◽  
Axial Stability ◽  
Displacement Capacity ◽  
Strength Capacity ◽  
Lateral Reinforcement

Abstract: Hollow Concrete Columns (HCCs) are one of the preferred construction systems in civil infrastructures including bridge piers, ground piles, and utility poles to minimize the overall weight and costs. HCCs are also considered a solution to increase the strength to mass ratio of structures. However, HCCs are subjected to brittle failure behaviour by concrete crushing means that the displacement capacity and the strength after steel yielding in HCCs are decreasing due to the unconfined concrete core. Absence of the concrete core changes the inner stress formation in HCCs from triaxial to biaxial causes lower strength. A new type of Hollow Composite Reinforcing System (HCRS) has recently been designed and developed to create voids in structural members. This reinforcing system has four external flanges to facilitate mechanical bonding and interaction with concrete. Therefore, providing the inner Hollow Composite Reinforced Sections (HCRS) can significantly increase strength by providing a higher reinforcement ratio and confining the inner concrete core triaxially. The corrosion of steel is also a notable factor in the case of steel reinforced HCCs which became more critical because their outer and inner surfaces exposing more concrete surface area. An alternative reinforcement is Glass Fibre Reinforced Polymer (GFRP) bars, can overcome the brittle behaviour of steel reinforced HCC. In previous studies, HCC shows high strength capacity, when appropriate reinforcement in the form of longitudinal GFRP bars, laterally using GFRP spirals and internally using rectangular HCRS which provide enough inner confinement. However, the spirals laterally restrict the expansion of the concrete core and limit the buckling of the longitudinal bars, allowing the columns to keep resisting applied loads and gives maximum strength. Therefore, in this study, the spirals are replaced by discrete hoops as lateral reinforcement to analyse the effect on structural behaviour of HCC reinforced with rectangle shaped HCRS under axial load using ANSYS software. The results show that column laterally reinforced with spiral attained insignificant increase in strength than their counterpart specimens confined with hoops. So, the circular hoops were found to be as efficient in confining concrete as spirals in a column reinforced internally with rectangle shaped HCRS. The increase in volumetric ratio can be achieved by reducing the spacing between lateral reinforcement. So, this study also investigates the effectiveness of reducing the spiral spacing in HCC reinforced with HCRS, three models with lateral spacing of 50mm, 40mm and 30mm are modelled and analysed. The results show that columns with closer spiral spacing attained more axial stability. Keywords: Hollow Concrete Column, Rectangular Hollow Composite Reinforced Sections, GFRP Spirals, GFRP Hoops, Nonlinear Static Analysis, ANSYS.

scholarly journals Analysis of Concrete Column Reinforced Internally with Hollow Composite Sections

2021 ◽  
Vol 9 (10) ◽  
pp. 1751-1759
Author(s):  
Sneha Nair M D
Keyword(s):  
Cross Sections ◽  
High Strength ◽  
Concrete Surface ◽  
Nonlinear Static Analysis ◽  
Concrete Column ◽  
Concrete Core ◽  
Civil Infrastructures ◽  
Gfrp Bars ◽  
Displacement Capacity ◽  
Strength Capacity

Abstract: Hollow Concrete Columns (HCCs) are one of the preferred construction systems in civil infrastructures including bridge piers, ground piles, and utility poles to minimize the overall weight and costs. HCCs are also considered a solution to increase the strength to mass ratio of structures. However, HCCs are subjected to brittle failure behaviour by concrete crushing means that the displacement capacity and the strength after steel yielding in HCCs are decreasing due to the unconfined concrete core. Absence of the concrete core changes the inner stress formation in HCCs from triaxial to biaxial causes lower strength. A new type of Hollow Composite Reinforcing System (HCRS) has recently been designed and developed to create voids in structural members. This reinforcing system has four external flanges to facilitate mechanical bonding and interaction with concrete. Therefore, providing the inner Hollow Composite Reinforced Sections (HCRS) can significantly increase strength by providing a higher reinforcement ratio and confining the inner concrete core triaxially. The corrosion of steel is also a notable factor in the case of steel reinforced HCCs which became more critical because their outer and inner surfaces exposing more concrete surface area. An alternative reinforcement is Glass Fibre Reinforced Polymer (GFRP) bars, can overcome the brittle behaviour of steel reinforced HCC. In previous studies, HCC shows high strength capacity, when appropriate reinforcement in the form of longitudinal GFRP bars, laterally using GFRP spirals and internally using newly developed HCRS which provide enough inner confinement. Therefore, this study aims to determine the effect of HCRS of different cross sections and also the effect of change in position of its flanges on the axial performance of HCC analytically using ANSYS software. Keywords: Hollow Concrete Column, Hollow Composite Reinforced Sections, GFRP bars, GFRP Spirals, Nonlinear Static Analysis, ANSYS.

Behaviour of reinforced GFRP bars concrete beams having strengthened splices using CFRP sheets

2021 ◽  
pp. 136943322110015
Author(s):  
Akram S. Mahmoud ◽  
Ziadoon M. Ali
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
New Method ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Strength Capacity ◽  
Cfrp Sheet ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

When glass fibre-reinforced polymer (GFRP) bar splices are used in reinforced concrete sections, they affect the structural performance in two different ways: through the stress concentration in the section, and through the configuration of the GFRP–concrete bond. This study experimentally investigated a new method for increasing the bond strength of a GFRP lap (two GFRP bars connected together) using a carbon fibre-reinforced polymer (CFRP) sheet coated in epoxy resin. A new splicing method was investigated to quantify the effect of the bar surface bond on the development length, with reinforced concrete beams cast with laps in the concrete reinforcing bars at a known bending span length. Specimens were tested in four-point flexure tests to assess the strength capacity and failure mode. The results were summarised and compared within a standard lap made according to the ACI 318 specifications. The new method for splicing was more efficient for GFRP splice laps than the standard lap method. It could also be used for head-to-head reinforcement bar splices with the appropriate CFRP lapping sheets.

Behaviour of steel–concrete–steel sandwich composite beams with lacing subjected to reversed cyclic loads

2017 ◽  
Vol 21 (6) ◽  
pp. 1799-1819 ◽  
Author(s):  
N Anandavalli ◽  
N Lakshmanan ◽  
J Rajasankar ◽  
GM Samuel Knight
Keyword(s):  
Energy Absorption ◽  
Composite System ◽  
Sandwich Composite ◽  
Dissipated Energy ◽  
Analytical Prediction ◽  
Hysteretic Model ◽  
Structural Behaviour ◽  
Concrete Core ◽  
Shear Connectors ◽  
Cover Plates

Steel–concrete–steel (SCS) sandwich composite system consists of steel plates covering both sides of the concrete core and connected by mechanical means such as shear connectors. In conventional steel–concrete–steel system, shear connectors are welded to the steel cover plates. Laced steel–concrete composite (LSCC) system is a new form of steel–concrete–steel, proposed earlier by the authors. In LSCC system, steel cover plates are connected in a novel way using lacings and cross rods and hence is devoid of welding. Proposed sandwich composite system is being evaluated systematically for its structural behaviour under various modes of loading for use in special structures under severe loading such as blast loading. Damage under cyclic loading and energy absorption are extremely important, which are highlighted in this paper. An experimental investigation on the cyclic response behaviour of two LSCC beams is carried out. Angle of lacing is the parameter that is varied between the two beams. Both the beams are found to exhibit similar behaviour on most of the aspects. The envelope of hysteretic response indicates mild softening behaviour after reaching peak value. Maximum load resisted under both sagging and hogging moment conditions is found to be nearly equal, thus making the LSCC system suitable for situations where reversal of loads are encountered. Dissipated energy is observed to be nearly the same for the load applied in the upward as well as in the downward direction. Analytical prediction on energy absorption capacity is carried out by adopting a hysteretic model with strength deterioration. Cyclic ductility factor is evaluated to be about 20 for LSCC beams, while support rotation is calculated to be about 8° and 10° for beams with 45° and 60° angles of lacing, respectively. Spalling of concrete is prevented in LSCC beams by the steel cover plates.

scholarly journals Analysis of the behavior of reinforced concrete columns strengthened with sleeve wedge bolts and a self compacting concrete layer

2015 ◽  
Vol 8 (2) ◽  
pp. 88-99
Author(s):  
M. G. Marques ◽  
A. P. A. R. Liserre ◽  
R. B. Gomes ◽  
G. N. Guimarães
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Concrete Columns ◽  
Concrete Surface ◽  
Self Compacting Concrete ◽  
Reinforced Concrete Columns ◽  
Concrete Layer ◽  
Strength Capacity ◽  
Strengthening Technique

Strengthening of reinforced concrete columns by jacketing is one of the most common structural rehabilitation techniques in Brazil. For adequate performance, it is necessary, among others, to avoid detachment of the new concrete layer (strengthening material) from the old concrete substrate when the strengthened member is again in service conditions. This paper describes the test results of eight reinforced concrete rectangular columns subjected to combined compression and one-axis bending to evaluate the efficiency of using sleeve wedge bolts across the new concrete/old concrete interface to avoid detachment. The strengthening technique, in this case, consists of adding a layer of self-compacting concrete to one face of the column. Two columns tested were monolithic and named PO (original column) e PR (reference column). The other six columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and its results gave information about column behavior without the use of strengthening. Column PR had a 155mm by 250 mm rectangular cross section and its cross section dimensions matched the strengthened columns but it was cast monolithically. To improve bond conditions between the existing concrete and the new concrete, the concrete surface was roughened and the outermost aggregate was exposed using hydro jetting. Holes along the concrete surface were made to insert the wedge bolts responsible for increasing the bond between the two concrete surfaces. The difference among the six strengthened columns was the position and amount of bolts used. Results indicate that the position and amount of the bolts alters significantly the strength capacity of the columns, since premature rupture by concrete detachment was delayed.

scholarly journals Condition Assessment Techniques for Aged Fixed-Type Offshore Platforms Considering Decommissioning: a Historical Review

2020 ◽  
Author(s):  
Mohamed Mubarak Abdul Wahab ◽  
V. John Kurian ◽  
Mohd Shahir Liew ◽  
Do Kyun Kim
Keyword(s):  
Pushover Analysis ◽  
Historical Review ◽  
Structural Condition ◽  
Condition Assessment ◽  
Life Extension ◽  
Nonlinear Behaviour ◽  
Offshore Platforms ◽  
Structural Behaviour ◽  
Strength Capacity ◽  
Fixed Type

AbstractIn this study, the technical papers on structural condition assessment of aged fixed-type offshore platforms reported over the past few decades are presented. Other ancillary related works are also discussed. Large numbers of researches are available in the area of requalification for life extension of offshore jacket platforms. Many of these studies involve reassessment of existing platforms by means of conducting pushover analysis, a static nonlinear collapse analysis method to evaluate the structure nonlinear behaviour and capacity beyond the elastic limit. From here, the failure mechanism and inherent reserve strength/capacity of the overall truss structure are determined. This method of doing reassessment is described clearly in the industry-adopted codes and standards such the API, ISO, PTS and NORSOK codes. This may help understand the structural behaviour of aged fixed offshore jacket structures for maintenance or decommissioning.

Performance of high strength concrete-filled steel columns exposed to fire

1998 ◽  
Vol 25 (6) ◽  
pp. 975-981 ◽  
Author(s):  
VKR Kodur
Keyword(s):  
Fire Resistance ◽  
High Strength Concrete ◽  
High Strength ◽  
Experimental Program ◽  
Structural Behaviour ◽  
Steel Columns ◽  
Strength Concrete ◽  
Normal Strength ◽  
Concrete Filling ◽  
Hollow Structural Section

Results from an experimental program on the behaviour of high strength concrete-filled steel hollow structural section (HSS) columns will be presented for three types of concrete filling. A comparison will be made of the fire-resistance performance of HSS columns filled with normal strength concrete, high strength concrete, and steel-fibre-reinforced high strength concrete. The various factors that influence the structural behaviour of high strength concrete-filled HSS columns under fire conditions are discussed. It is demonstrated that, in many cases, addition of steel fibres into high strength concrete improves the fire resistance and offers an economical solution for fire-safe construction.Key words: high strength concrete, steel columns, fire-resistance design, high-temperature behaviour, concrete-filled steel columns.

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