Redzuan Abdullah

Precast lightweight foamed concrete sandwich panel (PLFP) tested under axial load: preliminary results

A study is carried out to develop a Precast Lightweight Foamed Concrete Sandwich Panel, PLFP, as a new and affordable building system. Experimental investigation to study the behaviour of the panel under axial load is undertaken. The panel consists of two lightweight foamed concrete wythes and a polystyrene insulation layer in between the wythes. The concrete panels are reinforced with 9mm diameter high tensile steel bars. The rebars are tied to each other through the insulation layer by shear connectors which are made of 6mm mild steel bars bent to 45º angle. Total number of four specimens was tested with one specimen; PA1 was cast without capping at both ends. It was used as a pilot test. The other three specimens are capped with normal concrete at both ends to avoid end crushing during axial loading. Axial load test was conducted and the results are presented here, which include the ultimate load capacity, crack pattern and failure mode, strain distribution and load-deflection curve of the panels. The experimental ultimate strength achieved recorded lesser percentage difference with the formulae by Pillai and Parthasarathy when compared to formulae in BS8110. It is also observed that the strength of the panels are affected by the compressive strength of the foamed concrete forming the wythes, the presence of concrete capping at panel’s ends and the slenderness ratio, H/t. Specimens with capping at both ends recorded higher ultimate loads with no premature crushing. Failure of panels with slenderness ratio, H/t < 18 were by premature buckling near the supports whereas for panels with higher H/t ratio, slight bending was observed in the middle zone. The results also indicate that a certain degree of compositeness is achieved between the wythes.

Characterization of shear bond stress for design of composite slabs using an improved partial shear connection method

AbstractEurocode 4 design provisions specify two methods for the design of composite slabs, namely the m-k and the partial shear connection (PSC) methods. Currently, the m-k method includes the concrete thickness and the shear span of the slab as variables while the PSC method does not. This has resulted in a better accuracy for the m-k method when slabs with varying dimensions are considered. It is demonstrated in this paper that the horizontal shear bond stress varies with the ratio of shear span to effective depth of slab, defined as the slenderness. To include such an effect, a linear shear bond-slenderness equation is proposed. Using the proposed relationship, a linear interpolation of shear bond strength based on two configurations, determined from the outcomes of the bending tests for compact and slender slabs, has been satisfactorily performed. The shear bond strength obtained from this interpolation can be used in collaboration with the existing PSC method, such that the accuracy of the predictio...

Elemental bending test and modeling of shear bond in composite slabs

This paper discusses a new experimental bending test and shear bond modeling of steel deck reinforced concrete (composite) slabs. The objective of experimental work is to develop a new elemental bending test method for evaluating the performance and behavior of composite slabs, and also for determining the shear interaction property for use in numerical analysis. The analytical study is conducted to determine whether data from the small scale tests can be used in the present shear bond (m-k) and Partial Shear Connection (PSC) methods, to predict the strength of the actual slabs, to use the same test data for input in numerical analysis, and to improve the existing PSC design procedure. The results of the study demonstrate that the elemental bending test of composite slab using trapezoidal shape steel deck is feasible as a replacement for the full-size test utilizing the same steel deck. Data from the elemental bending test can be used not only in the existing analytical methods but also in the numerical analysis, thus eliminating the need for separate push off type tests. The improved PSC design procedure is found to be comparable with the m-k method.

Effect of Shear Reinforcement as Horizontal Restraint on the Bearing Capacity of Bridge Deck Slab using Strut-and-Tie Model

The purpose of this paper is to carry out an analysis and provide a design method for the disturbed/discontinuous regions of concrete bridge deck slab-on-girder, with simplicity and accuracy using strut-and-tie model. Strut-and-tie model in designs of reinforced concrete structures involve the use of some basic tools that include struts, ties and nodes. The method is very powerful but indirect for analysing reinforced concrete complex structures. In this study, the combined geometry of the deck slab and T-beam constituting a corbel-like geometry providing a region of geometric discontinuity produces a non-linear strain distribution. This behaviour enables the development of a modified strut-and-tie model for the system of an existing case-study Bridge. The Strut-and-tie model was developed using different types of configurations and eventually, a much simpler and precise solution is obtained. The concrete and shear reinforcement constitute the model elements in which, an efficient ultimate capacity for the system is obtained without incorporating the contribution of transverse steel reinforcement in the deck slab.

Traditional formwork system sustainability performance: experts’ opinion

The traditional formwork system is one of the commonly used systems in concrete construction. It is considered as one of the least observed activities in term of sustainability performance. In this paper, the sustainability performance of the traditional formwork has been assessed by using a multi-criteria assessment tool to facilitate the decision on the sustainability performance measurement. A quantitative five Likert scale survey study using judgemental sampling is employed in this study. A sample of 93 of engineering construction experts, with different fields including contractors, developers, and consultants in the Malaysian context has made the body of the collected primary data. The results show variety in the distribution of the respondents working experience. The sustainability performance is considered moderately sustainable by the experts with only given 40.24 % of the overall total score for the three sustainable categories namely environmental, social and economic. Despite the finding that shows that the economic pillar was rated as the most sustainable aspect in comparison to the environmental and social pillars the traditional formwork system sustainability still needs enhancement. Further incorporation of the social and environmental pillars into the concrete construction the sustainability performance of traditional formwork system could be improved.

Experimental Study for Structural Behaviour of Precast Lightweight Panel (PLP) Under Flexural Load

Precast lightweight concrete slab is first fabricated in workshop or industrial before nconstruction and then transported to site and installed by skilled labour. It can reduce nconstruction time by minimizing user delay and time for cast-in-situ to increase workability and nefficiency. is environmental friendly and helps in resource reduction. Although the foamed nconcrete has low compressive strength compared to normal weight concrete but it has excellent nthermal insulation and sound absorption. It is environmental friendly and helps in resource nreduction. To determine the material properties of foamed concrete, nine cubes and six ncylindrical specimens were fabricated and the results were recorded. In this study, structural nbehaviour of precast lightweight panel (PLP) with dry density of 1800 kg/m3 was tested under nflexural load. The results were recorded and analysed in terms of ultimate load, crack pattern, nload-deflection profiles and strain distribution. Linear Voltage Displacement Transducers n(LVDT) and strain gauges were used to determine the deflection and strain distribution of PLP. nThe theoretical and experimental ultimate load of PLP was analysed and recorded to be 70 and n62 kN respectively, having a difference of 12.9%. Based on the results, it can be observed that nPLP can resist the adequate loading. Thus, it can be used in precast industry for construction npurposes.

Development of precast lightweight foamed concrete sandwich panel (PLFP) with double shear truss connector: an overview

Urbanization in many cities needs to adopt modern and innovative techniques in the construction industry to balance the supply and demand in housing issues. To address the issue, there is a need to look for alternative solutions and provide affordable quality housing. Therefore, innovative construction method such as Industrialized Building System (IBS) needs to be adopted to move away from conventional building construction technique in order to meet the demand. Precast Sandwich panel is one of the alternative IBS that could meet and fulfil this target. Previous research had shown that this panel had a potential to provide possible solution to housing problems especially in low and medium cost housing sector. This paper presents findings from previous research in this field especially on the panels materials properties, structural behaviours and empirical expression to determine its ultimate load carrying capacity. It is hoped the overview on this topic could be used as guidance for future research on developing a lightweight sandwich panel system in low to medium rise building.

Closure to Determination of Composite Slab Strength Using a New Elemental Test Method by Redzuan Abdullah and W. Samuel Easterling

The objective of the study was to develop a method to test composite slabs using small-scale specimens instead of the usual full-scale specimens that are recommended in most codes of practice. Test 13 in Series 1 was the first trial in which the straps were placed at 150 mm on center. As large vertical separation between the concrete and the steel was observed during this test, it was assumed that this strap spacing might not be effective in preventing the steel web from curling. For the next tests in the same series, straps were placed at 100 mm. Upon comparing the results with the full-scale data, it was found that the capacity matched that found in the full-scale tests. At this point, because the objective of the test had been met, we concluded that there was no need for carrying out additional tests with strap spacing more or less than 100 mm. The restraining effect reached a plateau, as measured by the comparison with full-scale tests, and hence the shear bond strength will not be increased more than the maximum shear bond capacity with fully restrained webs for a particular configuration. Therefore straps at 100 mm are deemed sufficient and are suggested as a general rule, at least as applicable to the type of deck, dimension of the specimen, steel sheet thickness, and strap stiffness that are within the scope of this study.