Papers by Sri Kalyana Rama J
Evaluation of Efficiency of Non-destructive Testing Methods for Determining the Strength of Concrete Damaged by Fire
Advances in Structural Engineering, 2014
ABSTRACT An engineering assessment was performed on concrete cubes casted from M25 concrete for c... more ABSTRACT An engineering assessment was performed on concrete cubes casted from M25 concrete for checking the efficiency of non-destructive testing methods namely Schmidt’s rebound hammer test and Ultra Sonic Pulse Velocity test. The study was aimed at checking the viability of these above named non-destructive tests. Firstly, in the case of undamaged concrete structures and later on in the case of concrete structures damaged by fire, and then to compare the results to find out the efficiency of non-destructive testing methods. It is assumed that in the case of an undamaged structure the concrete is a homogenous mixture with equal strength at all depths. Hence, the non-destructive tests even if they are able to measure the surface strength like in case of the rebound hammer test may give a pretty accurate value when compared to the compressive tests performed in the laboratory. In the case of a structure, which has been damaged by fire, the concrete may no longer be homogenous at all depths and there might be considerable changes in its internal structure. Hence, this study is an attempt to carry out non-destructive tests on such concrete samples, which have been damaged by fire and then find out the viability and accuracy of the results when compared to the compressive tests performed in the laboratory.
Experimental Investigation and Numerical Validation on the Effect of NaOH Concentration on GGBS Based Self-compacting Geopolymer Concrete
Advances in Structural Engineering, 2014
ABSTRACT The construction sector is booming all over the world with an increase in the demand for... more ABSTRACT The construction sector is booming all over the world with an increase in the demand for the production of cement. Cement produced by India by the end of the financial year 2012–2013 was about 8 % of the global production. Cement production accounts for 7 % of total CO2 emission into the atmosphere. It’s high time for a sustainable replacement for cement in order to prevent greenhouse effect and global warming and other environmental impacts. In the present study, laboratory tests were conducted to investigate the effect of sodium hydroxide concentration on the fresh properties and compressive and flexural strength of self-compacting geopolymer concrete (SCGC) incorporating ground granulated blast slag (GGBS). The experiments were conducted for five different molarities of NaOH varying between 3 and 11 M with an increment of 2 M. In order to investigate the fresh concrete properties of SCGC, slump flow, V-Funnel, and T50 tests were carried out. The workability of GGBS based self-compacting geopolymer concrete showed an evident decrease with the increase in sodium hydroxide concentration. Standard cubes and beams were casted and cured in the open atmosphere. Its 28 days compressive strength and flexural strength were found to be decreasing with the increase in sodium hydroxide concentration. Using ABAQUS numerical modeling for compressive strength and flexural strength was determined and the results obtained were found to be similar to that of the experimental results.
Influence of Size Effect on Fracture properties of Concrete-Computational Approach
It is commonly accepted that there is a size effect on the nominal resistances of quasi-brittle m... more It is commonly accepted that there is a size effect on the nominal resistances of quasi-brittle materials such as cementitious materials. This effect must be taken into account in the design of the ultimate behavior of concrete structures in order to avoid damage and crack openings. Different theories exist in the literature to describe the size effect. Among them, we find the deterministic theory of Bazant where fracture energy is considered independent of the size and it is assumed that at peak load, the crack length is proportional to the size of the specimen. In this work, attention is paid to investigate numerically, the relationship between crack openings and length, and the size of the specimens. Various fracture parameters have also been studied by validating with the existing work for a concrete of grade M35 . The present study shows the determination of fracture parameters of beams, size-ranging from 100-400 mm using ABAQUS.
Study on the Behavior of Box Girder Bridge
“When tension flanges of longitudinal girders are connected together, the resulting structure is ... more “When tension flanges of longitudinal girders are connected together, the resulting structure is called a box girder bridge”. The behavior of box girder section for a general case of an eccentric load has been studied and presented its studies in chapter 2. An encompassing review of literature has been made regarding construction and a summary of general specifications with reference to IRC:18 have been discussed in chapter 3. Box girders can be universally applied from the point of view of load carrying, to their indifference as to whether the bending moments are positive or negative and to their torsional stiffness; from the point of view of economy. An ongoing work has been taken as a case study for the present work. Analysis principles for torsion and distortion effects are applied to the section selected, and found satisfactory. Correspondingly, the problem has been analyzed and designed for flexure and shear by giving due considerations for torsional and distortional effects a...
Cracks in a building are of common occurrence. A building component develops cracks whenever stre... more Cracks in a building are of common occurrence. A building component develops cracks whenever stress in the component exceeds its strength. Cracks are classified in to structural and non structural categories. The structural ones are due to faulty design, faulty construction or overloading which may endanger safety of buildings. The non structural cracks are due to internally induced stresses. Depending on width of crack, these are classified in to thin (< 1mm), medium (1mm to 2mm) and wide (> 2mm wide). Internally induced stresses in building components lead to dimensional changes and whenever there is a restraint to movement as is generally the case cracking occurs. There are numerous causes of cracking in concrete, but most instances are related more to concrete specification and construction practices than by stresses due to induced forces.
A Review on Influence of superplasticizers on the strength characteristics of Self- Compacting Concrete
Self-compacting concrete has an enhanced ability to flow which results in an increased segregatio... more Self-compacting concrete has an enhanced ability to flow which results in an increased segregation and bleeding potential. These requirements make the use of mineral and chemical admixtures essential for self-compacting concrete. High flowing ability is achieved using superplasticizers, while stability against segregation is achieved either by using a large quantity of fine materials, or by using appropriate viscosity modifying agents. Superplasticizers and other additives are used in production of SCC; they have an impact on high fluidity and prevent segregation, the additions of fillers reduce the quantity of superplasticizers used in SCC mixes, compared to normal concrete. The superplasticizer and mineral admixture hold the aggregates in suspension, and the combination of powder materials is also used to control the hardened properties, such as strength. This paper reviews on the work done in the recent past with the usage of different superplasticizers and their influence on str...
Sustainable design of RC building portal frame through CO2 emission optimization using Cuckoo Search Algorithm (CSA)
The construction industry consumes huge amounts of energy and produces substantial pollution. The... more The construction industry consumes huge amounts of energy and produces substantial pollution. The operation of a building accounts for a large portion of its total CO2 emissions. Most efforts are focused on improving the energy efficiency related to the operation of a building. The relative importance of the energy and CO2 emissions from the construction materials increases with the increasing number of low-energy buildings. To minimize the life-cycle energy use of a building, the energy consumed from both materials in the construction phase as well as the energy consumed from the operation of the building must be reduced. In this study, an optimal design method for reinforced concrete building using a cuckoo search algorithm is proposed to reduce CO2 emissions from the structural materials in the construction phase, while satisfying the structural design criteria and constructability conditions. The optimal method is applied to a single storey portal RC frame, and the effective use...
Advances in Structural Engineering, 2014
In the recent past the use of Self compacting concrete as a primary structural material in comple... more In the recent past the use of Self compacting concrete as a primary structural material in complex structures such as tall buildings, submerged structures, bridges, dams, liquid and gas containment structure has increased enormously. Proper understanding of the structural behaviour of SCC is absolutely necessary in designing complex concrete structures. Due to the presence of micro-cracks and other inherent flaws, the strength of the concrete structure decreases. Engineering fracture mechanics can deliver the methodology to compensate the inadequacies of conventional design concepts. It might be expected that SCC would exhibit more brittle behaviour than normal conventional concrete. The improved pore structure and better densification of matrix has great influence on the fracture characteristics of SCC. It is widely agreed that the strength, elastic modulus and fracture resistance of SCC slightly decreased with increased paste content. Increasing the volume of paste tended to make SCC brittle. Due to the quasi-brittle nature of concrete; various computational fracture models have been developed to study the crack characterizing parameters in concrete structures, such as fictitious crack model, crack band model, two parameter fracture model, size effect model, smeared crack model, cohesive crack band model and effective crack model. Compared to conventional vibrated concrete, self-compacting concrete often has a higher susceptibility to crack due to different mixture design, material properties and construction practices. Many studies have addressed the SCC fracture properties using different computational models. As mentioned above, all these studies are purely computational based and there is no support or evidence from the experimental view point. This paper deals with the various models as well as experimental investigations that have already been conducted by some of the researchers to study the exposure of Self Compacting Concrete to crack.
Formation of cracks in concrete is becoming a major threat in reducing the service life of a stru... more Formation of cracks in concrete is becoming a major threat in reducing the service life of a structure. Apart from the design standards for limit state of collapse it is also essential to analyze a structure for crack initiation and propagation. Modulus of Elasticity and Poisson's ratio of a material also play a crucial role in the release of energy during crack propagation. So, it is essential to analyze the structure considering the fracture behavior during crack propagation. The present work deals with the strengthening of plain and reinforced concrete plate subjected to fracture using Fiber Reinforced Polymer. A three-dimensional finite element analysis is carried out using ANSYS for obtaining the strain energy release rates for different types of concrete based on their Modulus of Elasticity and Poisson's ratio. Results obtained were in good agreement in arresting the crack growth when fibers are oriented at an angle of 45 0 in the plate. Strengthening of plain and reinforced concrete plates using fiber reinforced polymer-computational approach Sri Kalyana Rama. J, Panduranga Rao. B International Journal of Civil and Structural Engineering Volume 4 Issue 1 2013
Structures are classified as rigid and flexible. Tall structures are more flexible and susceptibl... more Structures are classified as rigid and flexible. Tall structures are more flexible and susceptible to vibrations by wind induced forces. In the analysis and design of high-rise structures estimation of wind loads and the inter storey drifts are the two main criteria to be positively ascertained for the safe and comfortable living of the inhabitants. Estimation of wind loads is more precise with gust factor method. Inter storey drift can be controlled through suitable structural system. The present investigation deals with the calculation of wind loads using static and gust factor method for a sixteen storey high rise building and results are compared with respect to drift. Structure is analyzed in STAAD Pro, with wind loads calculated by gust factor method as per IS 875-Part III with and without X-bracings at all the four corners from bottom to top.
Assumption of plane strain is valid for the structures made of isotropic and specially orthotropi... more Assumption of plane strain is valid for the structures made of isotropic and specially orthotropic materials. In case of generally orthotropic structure though the geometry, constraints and loading are symmetrical, the material arrangement may not permit to consider as a 2D plane strain problem such as an angle-ply laminate where the fibers are oriented in the plane of the plate. In such cases 3D analysis is required. However when the third dimension is infinitely long, the problem can be modeled with a finite length plate without losing the accuracy of the result. The present investigation deals with the identification of minimum length required to model an infinitely long FRP laminated plate under cylindrical bending with two different end conditions subjected to uniform pressure using three-dimensional finite element analysis. A four-layered angle-ply laminate with symmetric and anti-symmetric arrangement is modeled in ANSYS software and the required length for two different thickness ratios (S = 10, and 50) is determined based on the variation of transverse deflection and in-plane normal stress along the span direction of the plate.
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Papers by Sri Kalyana Rama J