Juki, Mohd Irwan (2010) Development of bentup triangular tab shear transfer (BTTST) enhancement in coldformed steel (CFS)concrete composite beams. Doctoral thesis, Universiti Teknologi Mara..

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Abstract
Coldformed steel (CFS) sections, have been recognised as an important contributor to environmentally responsible and sustainable structures in developed countries, and CFS framing is considered as a sustainable 'green' construction material for low rise residential and commercial buildings. However, there is still lacking of data and information on the behaviour and performance of CFS beam in composite construction. The use of CFS has been limited to structural roof trusses and a host of nonstructural applications. One of the limiting features of CFS is the thinness of its section (usually between 1.2 and 3.2 mm thick) that makes it susceptible to torsional, distortional, lateraltorsional, lateraldistortional and local buckling. Hence, a reasonable solution is resorting to a composite construction of structural CFS section and reinforced concrete deck slab, which minimises the distance from the neutralaxis to the top of the deck and reduces the compressive bending stress in the CFS sections. Also, by arranging two CFS channel sections backtoback restores symmetricity and suppresses lateraltorsional and to a lesser extent, lateraldistortional buckling. The twofold advantages promised by the system, promote the use of CFS sections in a wider range of structural applications. An efficient and innovative floor system of builtup CFS sections acting compositely with a concrete deck slab was developed to provide an alternative composite system for floors and roofs in buildings. The system, called Precast ColdFormed SteelConcrete Composite System, is designed to rely on composite actions between the CFS sections and a reinforced concrete deck where shear forces between them are effectively transmitted via another innovative shear transfer enhancement mechanism called a bentup triangular tab shear transfer (BTTST). The study mainly comprises two major components, i.e. experimental and theoretical work. Experimental work involved smallscale and largescale testing of laboratory tests. Sixty eight pushout test specimens and fifteen largescale CFSconcrete composite beams specimens were tested in this program. In the smallscale test, a pushout test was carried out to determine the strength and behaviour of the shear transfer enhancement between the CFS and concrete. Four major parameters were studied, which include compressive strength of concrete, CFS strength, dimensions (size and angle) of BTTST and CFS thickness. The results from pushout test were used to develop an expression in order to predict the shear capacity of innovative shear transfer enhancement mechanism, BTTST in CFSconcrete composite beams. The value of shear capacity was used to calculate the theoretical moment capacity of CFSconcrete composite beams. The theoretical moment capacities were used to validate the largescale test results. The largescale test specimens were tested by using fourpoint load bending test. The results in pushout tests show that specimens employed with BTTST achieved higher shear capacities compared to those that rely only on a natural bond between coldformed steel and concrete and specimens with Lakkavalli and Liu bentup tab (LYLB). Load capacities for pushout test specimens with BTTST are ii relatively higher as compared to the equivalent control specimen, i.e. by 91% to 135%. When compared to LYLB specimens the increment is 12% to 16%. In addition, shear capacities of BTTST also increase with the increase in dimensions (size and angle) of BTTST, thickness of CFS and concrete compressive strength. An equation was developed to determine the shear capacity of BTTST and the value is in good agreement with the observed test values. The average absolute difference between the test values and predicted values was found to be 8.07%. The average arithmetic mean of the test/predicted ratio (n) of this equation is 0.9954. The standard deviation (a) and the coefficient of variation (CV) for the proposed equation were 0.09682 and 9.7%, respectively. The proposed equation is recommended for the design of BTTST in CFSconcrete composite beams. In largescale testing, specimens employed with BTTST increased the strength capacities and reduced the deflection of the specimens. The moment capacities, MU ) e X p for all specimens are above Mu>theory and show good agreement with the calculated ratio (>1.00). It is also found that, strength capacities of CFSconcrete composite beams also increase with the increase in dimensions (size and angle) of BTTST, thickness of CFS and concrete compressive strength and a CFSconcrete composite beam are practically designed with partial shear connection for equal moment capacity by reducing number of BTTST. It is concluded that the proposed BTTST shear transfer enhancement in CFSconcrete composite beams has sufficient strength and is also feasible. Finally, a standard table of characteristic resistance, P t a b of BTTST in normal weight concrete, was also developed to simplify the design calculation of CFSconcrete composite beams.
Item Type:  Thesis (Doctoral) 

Subjects:  T Technology > TA Engineering (General). Civil engineering (General) T Technology > TA Engineering (General). Civil engineering (General) > TA630695 Structural engineering (General) 
Depositing User:  Mrs. Sabarina Che Mat 
Date Deposited:  03 Feb 2022 01:58 
Last Modified:  03 Feb 2022 01:58 
URI:  http://eprints.uthm.edu.my/id/eprint/3662 
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