Sri Kalyana Rama J

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.

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.

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.

“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 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.

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...

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...