Journal May 2019

Evaluation of one-way flexural behaviour of biaxial voided slab R Sagadevan, B N Rao

In recent years, different types of innovative slab systems are being developed and adopted all over the world. Voided slabs are one such slab system that reduces the self-weight up to 50 % in comparison with solid slabs without any significant change in its structural performance. One of the innovative slab systems namely two-way hollow core slab system (biaxial voided slab) consists of void formers with various shapes like spherical, donut, cuboid, etc. Experimental and analytical investigations were carried out to study the behaviour of biaxial cuboid voided slab under one-way flexure. Voided slab specimens were prepared and tested with commercially available cuboid void former, which is manufactured using recycled polypropylene. Comparison of experimental and analytical (using yield line analysis in conjunction with Indian Standards) studies shows that the ultimate load carrying capacity of voided slabs are approximately 90% of solid slab. From this study it is concluded that the yield line analysis can also be applied to biaxial voided slabs. Also, the stiffness (at yield) reduction in comparison with solid slab is about 40%. It is also found that the behaviour of voided slabs under one-way flexure can be predicted by provisions of Indian Standards with necessary correction for loss of cross-section caused by voids.

Optimization of thickness of pavement quality concrete slab using rice husk ash Paramveer Singh, Mandeep Kaur

There is growing interest in the construction pavements, due to its high strength, durability, better serviceability and overall economy in the long run. The thrust nowadays is to produce thinner sections of better quality, which can carry the heavy loads. The present study aims at, developing pavement quality concrete mixtures incorporating rice husk ash dust as partial replacement of cement. The aim is to the design of slab thickness of PQC pavement using the achieved flexural strength of the concrete mixtures. The flexural strength examined for different percentages of RHA with replacement of cement (by weight) i.e. for 5%, 10%, 15% and 20% for OPC 43 grade cement. As for PQC, flexural strength is optimized by designing thickness of slab for different percentage of RHA and compared with control mix, i.e. it is increased by 10.9% for M-RHA5 mix and then start decreasing for M-RHA10 by 3% as compared with control mix. For flexural strength optimum content for RHA in cement 5% i.e. M-RHA5 which will reduce the cost of construction for pavement quality concrete slab.

Regression analysis and optimization of rice husk ash based concrete mixes Kalyan Kumar Moulick, Amit Shiuly, Soumya Bhattacharjya

The application and process of Rice Husk Ash (RHA) based concrete has yet to be established in real-world conditions. Standard code for making a good RHA based concrete is lacking. Research works dealing specifically with regression analysis and optimization of RHA based concrete mixes are rare. The main aim of this research work is to conduct a regression analysis and optimization of RHA based concrete mixes. RHA concrete was produced by replacing Ordinary Portland Cement (OPC). Regression analysis and optimization along with statistical analysis of test results conducted. Optimization of mix was performed to get specific target compressive strength. Experimental validation was conducted for each optimized mix.

A comparative seismic analysis and design using etabs and staad pro Lamuo Francis Suglo, Monica Malhotra, Jaiprakash Naya

The paper presents how Extended Three dimensional Analysis of Building Systems (ETABS) software and Structural Analysis and Design Professional (STAAD Pro) each give steel reinforcement quantities against the provision of section 26.5 of Indian Standard (IS) 456:2000. It is factual that manually performing seismic analysis can be very tedious, timeconsuming and uncompetitive in an industry that is competition driven. In addition, the tendency of making errors due to the transposition of figures is high. Therefore, the need to adopt the computer and its program in the analysis and design of buildings and structures is overdue. However, it should not be at the expense of sustainability. The results of seismic analysis and design of a six storey (Ground floor plus five other floors referred to in this paper as G+5) building in ETABS software and STAAD Pro are used to examine how they both satisfy important provisions set out in the Indian Standard. Manual calculations were also done by following the provisions set out in IS 456:2000 and IS 1893 (Part I): 2016. The results shows ETABS gives much steel reinforcement in its output by 0.58% compared to STAAD Pro and 0.02% more than manually calculated result. In addition, the storey displacement, storey drift, base shear, moments and shear forces showed that there was an only marginal difference in the results from the ETABS and STAAD Pro analysis. ETABS analysis produced the highest values with a maximum difference of about 7% higher than results from the STAAD Pro analysis.

Non-destructive testing of bored piles using the low strain pile integrity method Brijesh Singh, V V Arora, Vikas Patel, Nitin Chowdhary

Non-destructive testing of piles has gained increased acceptance for various purposes such as Quality Control and Quality Assurance, verification of existing conditions, and quantification of dimensions. The correct use of this technique can greatly simplify and expedite investigation, and be economical in addressing concerns or questions on pile conditions. Equally, its incorrect use can cause controversies, delays or create adverse reputation for the technology. A defect present in pile will severely reduce the structural load carrying capacity of the pile. Therefore, post construction test to verify the integrity of piles are extremely important. A most commonly used post construction integrity test is a low strain Pile Integrity Test commonly referred as PIT. In this type of integrity test a low strain dynamic impulse is given to the pile top by hand held hammer and the velocity of pile top is monitored using accelerometer. The low strain impulse generates a low strain wave that propagates through the pile and reflected from various places where there is change in properties of concrete, cross-section area of pile or stiffness of soil surrounding the pile. Such defects are recorded based on reflections detected by accelerometer. The present paper covers the interpretation of pile integrity test conducted on different deep bored piles in project executed in Delhi. This paper also presents the signal characteristics and their interpretations from low strain pile integrity test performed on mainly bored piles varying in length, size, construction method and founded soil strata. In this paper, the locations of accelerometer on the pile head which has a major influence on the test signals also has been discussed.

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