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

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.

STUDY OF BEHAVIOR MECHANICALLY STABILIZED EARTH WALL (MSE-WALL) WITH SAND ON THE MODEL TEST IN THE LABORATORY

Different types of field conditions coupled with rapid technological developments gave birth to innovations in the construction of retaining walls. One type of landslide deterrence construction that began to be developed in Indonesia is the Mechanically Stabilized Earth Wall or often called the MSE wall. The main components of the MSE wall are backfill material, lateral reinforcement and facing panel. In this final project, research will be conducted to observe the behavior of MSE wall systems on a laboratory scale.The study was conducted by planning the innovation of the facing panel form and the variation in the number of reinforcement layers. The variations of reinforcement are 1 layer, 2 layers, 3 layers, 4 layers and without reinforcement. The reinforcement used is sack as a substitute for geotextile woven with selected pile material is sand. In testing the prototype of the MSE wall, a dial gauge is used to find out the deformation, while for loading it uses a jack-push tool.From these tests, the data obtained in the form of shifts, lateral stresses, and the maximum load of the results of the study showed that the application of reinforcement can affect the amount of lateral stress, shifting, and load. The minimum lateral stress is 0.023 kg/cm2 and the maximum load that can be held by the MSE wall is 75 kg.

Cyclic load Analysis of beam column joint using ANSYS

Work on FE analysis with the addition stirrup bar at different spacing in beam under the cyclic loading for strengthen the joint. The most important part of developing the beam column joint when cyclic loading take place in seismic zone. Six samples with different characteristic are chosen, design as per ductile detailing IS 13920-2016 and non-ductile detailing as per IS 456-2000 and design on ANSYS. The result shows that addition of lateral reinforcement have more shear strength. From the all sample the shear strength is high in addition of stirrups at L/3 scaled and L/4 scaled.

Effect of Foundation Pit With Different Support and Excavation Methods on Adjacent Buried Hydrogen Pipe

Support and excavation methods have a great effect on the supporting role of the foundation pit. To investigate the effect of foundation pit with different support and excavation methods on adjacent buried hydrogen pipe, a pipe–soil coupling model was established. Deformation, strain, and stress of the pipe near the foundation pit with different support and excavation methods were analyzed. The results show that stress concentration appears on the upper and lower surfaces of the middle part of the pipe after the foundation pit excavation. The high stress areas on the upper and lower surfaces are distributed symmetrically about the pipe center. Upper surface of the pipe's middle section is pressed and the lower surface is pulled, but the strain distribution of the pipe at the pit edge is opposite. Vertical displacement of the pipe is bigger than its horizontal displacement. The underground continuous wall as the most common support structure can effectively reduce the pipe deformation. Supporting methods have different effects on buried pipe's mechanical behavior. Lateral reinforcement, inner support, and bolt support can effectively reduce the pipe deformation, but the mitigating effect of lateral reinforcement is less than inner support and bolt support. The pipe is also affected by time and space of the foundation pit excavation. The slope excavation can greatly reduce the pipe deformation, but the effects of island excavation and basin excavation are not obvious. Those results can provide references for pipe safety assessment and protection.

Effect of Strengthening Axially Loaded Circular Self-Consolidating Short Columns with Expanded Metal Mesh

Superior confinement for concrete column cannot be provided by traditional lateral ties reinforcement due convergence of bends and twists caused due to lateral reinforcement. In this paper, the enhancement in confining the steel bars due to the utilization of metal mesh any case to the regular tie reinforcement is studied. Totally 5 column specimens were cast and cured. A control specimen was prepared and remaining 4 specimens were internally wrapped using Expanded Metal Mesh (EMM). Mesh Apertures are differed having constant mesh thickness. Self-Consolidating Concrete was adopted in place of congested reinforcement. The specimens were tested under uniaxial compression in universal testing machine until failure. The results show that the strength and ductility has been improved for internally confined concrete column specimens.

Effect of Grouted Granular Column on the Load Carrying Capacity of the Expansive soil

Due to the scarcity of land for the construction of industrial, commercial, and transportation structures for development in urban areas, it is very necessary to use the places which have weak strata. This has become very mandatory to use the land which has poor engineering properties due to the unavailability of land. In the recent years granular columns have come under the extensive use for increasing the load carrying capacity and reducing the settlement in the expansive soil and loose sand. Nowadays to increase the stability of the foundation, granular columns are being widely used. Traditional columns are driven into the weak expansive soil stratum and maintain its stability from lateral confinement, which is generally due to the reaction from the surrounding stiffened expansive soil. However, this is not so easy to support loose soil, an additional lateral support may have to be provided to stabilize it and reduce its settlements. This study aims to overcome this weakness in soil by wrapping the granular column in geotextile layer to enhance the lateral reinforcement. In the present paper the discussion is about the variation in load carrying capacity and settlement characteristics of granular column (made up of cement fly ash and sand in a definite proportion instead of aggregates and stones) and analyzing its effect on the expansive soil by comparing its results with geotextile encased columns. In this process the study investigates the improvement of load carrying capacity of a single granular column encased with geotextile through model test.

The Influence of Steel Fiber on the Stress-Strain Behavior of Confined Concrete

This paper presents the result of an experimental study of confined concrete to evaluate the stress-strain behavior of fiber-reinforced concrete, which includes strength and ductility. The effectiveness of steel fibers in influencing the stress-strain behavior was also evaluated by creating a conventional concrete as a control specimen. The experimental results showed that there was a decrease in the value of the increased strength of confined concrete (f’cc/f’co) when the compressive strength of the concrete increased. Reducing the spaces of lateral reinforcement spaces will also increase the strength and ductility of confined concrete. The comparison of experimental results with various confinement models shows that there are substantial differences in the peak stress and the descending behavior of confined fiber concrete.

The effect of anisotropy of elastic properties of GFRP reinforcement on strength of compressed concrete structural elements

Introduction. Despite the growing interest to the use of GFRP reinforcement in various concrete structures, its use in the concrete compressed zone is not investigated sufficiently. The use of GFRP reinforcement in compressed concrete elements is limited by a combination of low value of its modulus of elasticity and small ultimate deformation of concrete during compression. A number of researchers suggest solving this problem by means of increase the ultimate concrete deformation due to lateral reinforcement. However, unlike steel reinforcement, the elastic properties of composite reinforcement depend on the stress direction, which is due to the significant difference between the moduli of elasticity of the fibre glass and the binder. Consequently, the stress-deformation state of compressed concrete elements with longitudinal GFRP reinforcement and close-set lateral reinforcement will differ from the stress-deformation state of steel-reinforced concrete elements. Materials and methods. To clarify the effect of the anisotropy of fibre-glass reinforcement elastic properties on its work in the concrete compressed zone, a physical experiment and numerical simulation using the LIRA-SAPR software were carried out. Physical nonlinearity of materials was not taken into account in the model. Results. An assessment of the effect of anisotropy of elastic properties of fibre-glass reinforced plastic (GFRP) reinforcement on the strength of compressed concrete elements was accomplished for longitudinal reinforcement. The experiment showed that the location of the longitudinal GFRP reinforcement in the concrete compressed zone in the absence of lateral reinforcement led to a decrease in the average strength of the tested samples by 9.2 %, while the fracture nature of GFRP-reinforced samples differed from the fracture nature of control samples. As a result of the numerical simulation, it was revealed that the cause of the strength reduction is the anisotropy of the elastic properties of GFRP reinforcement, which affects the stress-deformation state of compressed concrete. Conclusions. The analysis of the results of experiment and numerical simulation showed that the reason for the decrease in strength is the low modulus of elasticity of GFRP when compressed in the lateral direction as compared with the similar characteristic of concrete. The degree of strength reduction will also depend on the relation between the moduli of elasticity of concrete and GFRP when compressed in the longitudinal direction.