S. J. Karthik Pandian ¹, A. Ramachandra Murthy ², M. Helen Santhi ¹

Affiliations
1 Structural Engineering Division, SMBS, VIT University Chennai campus, Chennai-600127, Tamilnadu, IN
2 Computational Structural Mechanic Group, CSIR-SERC, Taramani, Chennai-600113, Tamilnadu, IN

Abstract

The present study aims to investigate the use of Ultra High Strength Cementious Composite (UHSCC) overlay strips for strengthening of pre-damaged RC beams. Fatigue loading was conducted in the study, one control beam was tested up to failure. Preloading of 80-90% in terms of number of cycles to failure was applied keeping stress ratio as 0.2 and frequency as 3Hz. Constant amplitude loading spectrum with different maxima minima but keeping stress ratio same was applied to control beam to examine any changes in structural behavior such as deflection and stiffness degradation of beams. The beams used were made of RCC with dimension 1500x100x200mm. The strengthened beams were tested to extract the parameters such as cycles for failure, load, deflection, crack initiation and failure phenomenon. It was observed that the beams retrofitted with UHSCC overlay strips performed efficiently in terms of number cycles to failure in comparison with conventional RCC beams under fatigue loading. Preloaded fatigue beam (FB1) had 17.6% higher load carrying capacity as compared to the control beam. Similarly preloaded fatigue beam (FB2) had 11.7% higher load carrying capacity as compared to the control beam. Acoustic Emission technique is a novel Non-destructive testing method which is used to identify the crack propagation and physical behavior of the beam at selected locations during the onset of loading, which gives a precise idea of the crack initiation and crack propagation under different loading condition.

Keywords

Acoustic Emission, Cycles for Failure, Fatigue, Preloading, Strengthening, Ultra High Strength Cementious Composite

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M. Shanmugapriya ¹, M. Helen Santhi ²

Affiliations
1 Department of Civil Engineering, Sathyabama University, Chennai - 600119, Tamil Nadu, IN
2 Department of Civil Engineering, VIT University, Chennai - 600127, Tamil Nadu, IN

Abstract

The experimental investigation was carried to study the investigate the behaviour of hollow, Plain Cement Concrete (PCC) and Silica; Quartz replaced concrete in-filled medium light gauge columns subjected to axial loads. The Cold formed sheets were welded continuously welded at the middle along its length. The basic study for the infill materials were carried out initially. For PCC in-fill M40 grade concrete were chosen. A total of 04 columns of 1.50m length were tested, without in fill, with plain concrete in-fill and with Quartz and Silica in-fill having a cross section of 100 x 50x 2mm. All the specimens were tested to failure. Ultimate load, Load – Axial shortening and Load-Strain for all the specimens tested were plotted. With the comparison of hollow columns the Quartz concrete in-filled columns take around 50% more ultimate loads when loaded axially. The in-filled column with Quartz withstands the maximum load; this is due to the fineness modulus property of the material. The Euro Code 4 predicted the ultimate loads closer to that of the experimental loads. Thus Quartz Sand can be used as an alternate filler material.

Keywords

Aggregate, Cold Formed, Concrete, In-Filled, Quartz, Silica

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