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Structural behaviour of precast lightweight foamed concrete sandwich panel (PLFP) with double shear truss connectors under eccentric load: preliminary result

Structural behaviour of precast lightweight foamed concrete sandwich panel (PLFP) with double shear truss connectors under eccentric load: preliminary result

Comparison of the Ultimate Load Bearing Capacity of PLFP with Theoretical Values. Table 3 shows the ultimate load carrying capacities of PLFP obtained from classical formulas [4][5][6][7]. The result of the ultimate load carrying capacity showed that result from experimental work achieved adequate and higher strength than the value from classical formulas. The percentage differences from classical formulas ranged from 38.01% to 54.68%. Classical formulas obtained lower values compared to experimental result because it did not take into account the factor of double shear truss connectors. It showed that the use of Double shear truss connectors was able to increase the strength of PLFP and the system can be used as load bearing wall.
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The structural behaviour of precast lightweight foamed concrete sandwich panel as a load bearing wall

The structural behaviour of precast lightweight foamed concrete sandwich panel as a load bearing wall

4. To develop a semi-empirical expression to estimate the load carrying quire this country to look for alternative construction method to provide fast and affordable quality housing to its citizens. Efforts have been taken to move from the traditional building construction technique to a more innovative construction method to meet these demands. As a part of this effort, an extensive investigation to develope a Precast Lightweight Foamed Concrete Sandwich Panel or PLFP as a load bearing wall system is undertaken.

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Structural behaviour of precast lightweight foamed concrete sandwich panel (PLFP) with shear truss connectors

Structural behaviour of precast lightweight foamed concrete sandwich panel (PLFP) with shear truss connectors

This study is aimed to provide information about the structural behaviour of PLFP with shear connectors. It is able to get a clear and deeper insight on the structural behaviour and failure mechanisms of the PLFP with single and double shear truss connectors under axial and push off loading. The results from this study are very important to assist the design of the PLFP to be used as a precast wall system especially the ultimate load carrying capacity and failure mechanism. An empirical equation is proposed in this study which is able to predict the ultimate load carrying capacity of PLFP under axial loading. The equation can be used to predict the maximum load of sandwich in non-linear behaviour after the service load.
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Structural behaviour of precast lightweight foamed concrete sandwich panel under axial load: an overview

Structural behaviour of precast lightweight foamed concrete sandwich panel under axial load: an overview

Tarek K. Hassan and Sami H. Rizkalla (2010), on the studies of “Analysis and design guidelines of precast, prestressed concrete, composite load-bearing sandwich wall panels reinforced with CFRP grid”, investigated three different precast concrete sandwich wall panels, reinforced with carbon-fiber-reinforced-polymer shear grid and constructed using two different types of foam, expanded polystyrene (EPS) and extruded polystyrene (XPS), were selected from the literature to validate the proposed approach. The results of the analysis indicated that the proposed approach is consistent with the actual behavior of the panels because the predicted strains compared well with the measured values at all load levels for the different panels. Besides that, the approach is beneficial to determine the degree of the composite interaction at different load levels for different panels at any given curvature. A simplified design chart is provided to calculate the nominal moment capacity of EPS or XPS wall panels as a function of the maximum shear force developed at the interface. A simplified design chart is proposed to calculate the nominal moment capacity of EPS and XPS foam-core panels at different degrees of composite interaction. The chart is valid only for the panel configuration, geometry, materials, and reinforcement used in the current study. However, it can easily be produced for different panels. The chart demonstrates the effect of composite interaction on the induced curvature.[19]
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Structural Behaviour of Precast Lightweight Foamed Concrete Sandwich Panel under Axial Load: An Overview

Structural Behaviour of Precast Lightweight Foamed Concrete Sandwich Panel under Axial Load: An Overview

Tarek et al.[15], investigated three different precast concrete sandwich wall panels, reinforced with carbon- fiber-reinforced-polymer shear grid and constructed using two different types of foam; namely, expanded polystyrene (EPS) and extruded polystyrene (XPS). The results of the analysis indicated that the proposed approach is consistent with the actual behavior of the panels because the predicted strains compared well with the measured values at all load levels for the different panels. Besides that, the approach is beneficial to determine the degree of the composite interaction at different load levels for different panels at any given curvature. A simplified design chart is provided to calculate the nominal moment capacity of EPS or XPS wall panels as a function of the maximum shear force developed at the interface. A simplified design chart is proposed to calculate the nominal moment capacity of EPS and XPS foam-core panels at different degrees of composite interaction. The chart is valid only for the panel configuration, geometry, materials, and reinforcement used in the current study. However, it can easily be produced for different panels. The chart demonstrates the effect of composite interaction on the induced curvature.
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The structural behaviour of precast lightweight foamed concrete sandwich panel as a load bearing wall

The structural behaviour of precast lightweight foamed concrete sandwich panel as a load bearing wall

ated from Scandinavia some thirty years ago. Nowadays, foam concrete technology has been widely used in construction industries. It is considered as an attractive material for its lightweight, better thermal properties and ease of construction. In the United States for instance, foamed concrete are used in an increasing number of applications. Cast-in-place foamed concrete are used for insulating roof-deck systems and for engineered fills for geotechnical applications while precast auto-claved products are widely used as load-bearing blocks, reinforced wall, roof and floor units and as non load-bearing cladding panels over a primary structural frame (Tonyan and Gibson, 1992).
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Study on precast lighweight foamed concrete sandwich panel (PLFP) connection under flexural load

Study on precast lighweight foamed concrete sandwich panel (PLFP) connection under flexural load

The scope of study will focused on experimental work on the design connection of load bearing PLFP panels. The size of the panels is 900mm height,600 mm height and 300mm height with the same 370mm width and 90mm thick. Connection used is vertical connection which uses plane surface type of connection. The connected wall is justified to be under bending situation due to settlements and also beam deflection. Eight panels were used in this experiment with the same type of connection including one panel for pilot and one panel as control with no connection .The material used is foamed concrete with density1700 – 1800 kg/m 3 as for the panel and the in-fill of the connection is normal mortar with have cement-sand ratio of 1:3. The reinforcement bar 4mm diameter and shear connectors 3mm diameter of mild steel used in this experiment. All of the panel were tested under flexure test.
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OVERVIEW OF EMPIRICAL EQUATION PREDICTION FOR ULTIMATE AXIAL LOAD OF PRECAST LIGHTWEIGHT FOAMED CONCRETE SANDWICH PANEL (PLFP)

OVERVIEW OF EMPIRICAL EQUATION PREDICTION FOR ULTIMATE AXIAL LOAD OF PRECAST LIGHTWEIGHT FOAMED CONCRETE SANDWICH PANEL (PLFP)

Precast sandwich panel presents a series of possibilities for the solution of housing problems especially in low and medium cost housing sector [1-5], Sandwich panels have all the desirable characteristics of a normal precast concrete wall panel such as durability, economical, fire resistance, large vertical spaces between supports, and can be used as shear walls, bearing walls, and retaining walls. It can be located to accommodate building expansion need. In addition, the insulation property provides superior energy performance compared to other wall systems [1].
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CFRP Grid/Rigid Foam Shear Transfer Mechanism for Precast, Prestressed Concrete Sandwich Wall Panels.

CFRP Grid/Rigid Foam Shear Transfer Mechanism for Precast, Prestressed Concrete Sandwich Wall Panels.

Structural demand from applied gravity and wind loading induce flexural, shear, tension, and compression stresses in the precast concrete sandwich panels. Resisting these demands in the most efficient way requires some degree of composite action be achieved between the two separate concrete wythes of the sandwich panel. This can be accomplished by providing sufficient shear reinforcement to transfer the forces from the inner to the outer concrete wythe, through the insulation core. Shear connectors and/or solid concrete zones are used to transfer the applied forces and resist the load as a composite cross section. Three different methods can be used to determine the magnitude of the shear force generated by the applied load and are described in the following sections. The quantity of shear reinforcement required to develop composite action can then be determined based on the shear force and the shear capacity of the connector. To ensure composite action between the inner and outer concrete wythes is achieved, the quantity of shear grid required for a certain cross-section of the panel can be computed as follows:
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accordance with the requirements contained in [1] while the other constituents, sand, cement, rice husk ash and water occupied the remaining 80 %. All the constituent materials including water were proportioned by weight and properly mixed until a very uniform, consistent and well blended mixture was obtained. The foam from the pre-mixed Segun Ilori Engineering Limited (SIEL) foaming agent was prepared in a SIEL Premium Mini Foam Generator and the specified quantity of foam was injected into the wet mix while mixing the other components of the mixtures, blended together until a homogenous mixture was achieved. The concrete cube samples were cast and demoulded after 24 hours, cured in water at ambient temperature of 25 0 C for 28 days and
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Cellular Lightweight Concrete Compressive Strength Prediction Using Support Vector Regression

Cellular Lightweight Concrete Compressive Strength Prediction Using Support Vector Regression

Based on the investigation on the production method of foam concrete, researchers have pointed out that two methods could be used [1], [2]: the first one, the so-called pre-foam method, using stable foam made by foam agent, water, cement paste or mortar, and finally mixing all the components together. The second method, namely the mixed foaming method, where the foaming agent is added into the pre- prepared mixture and a cellular structure in concrete is produced during the mixing process. The compressive strength of lightweight concrete is an important mechanical property, which need to be pre-defined before any further utilization. Several empirical approaches have been proposed in the literature, which pointed out that the mixture components and the corresponding proportions highly affected the compressive strength of cellular lightweight concrete [3]– [5]. A design expert technology and the use of a response surface methodology (RSM) were utilized to provide a relationship between all the lightweight concrete constituents and the corresponding mechanical behaviors [6]. Besides, experimental approach was also conducted to study the compressive strength in function of time or the effect of foam content in the mixture, for instance the works of Bing et al. [7] or Liu et al. [8]. Overall, empirical equations or semi-analytic equations were developed but the values of several constants in such equations were required, making such approach difficult to use. In recent decades, soft computing techniques based on machine learning have paved the way to a great benefit, especially in using existing database to avoid unnecessary experiments. Many complex problems, difficult to deal using classical approaches have been solved thanks to machine learning algorithms, including structures [9]–[11], materials [12], [13] or soil mechanics [14]. Thus, it could strengthen the fact that these machine learning based algorithms should be applied and tested to various problems to evaluate the accuracy of such approach.
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Structural performance of FCS wall subjected to axial load

Structural performance of FCS wall subjected to axial load

The maximum horizontal displacement recorded from the FEM simulation on all FCS-F panels are found to increase with the increase of slenderness ratio. This is as expected for walls sub- jected to compressive axial load where they behave just like col- umn as described previously in Section 4.1. Horizontal displacements of FCS-F1 to FCS-F11 walls at mid height are as shown in Fig. 11(a). As evident in the figure, trends for horizontal displacement increments at the mid-height of wall were similar for all FCS-F walls, where the horizontal displacement increased gradually with the increase of the load during the elastic stage. When the wall entered the plastic stage, the trend of curves becomes non-linear from first cracking until it reached the ulti- mate load. For FCS-F wall with lower slenderness ratio, cracking, yielding and crushing occurred when the panel reached the ulti- mate loading. This phenomenon was reduced when the H/t of walls increased. Buckling and out of plane bending occurred but walls tend to sustain the load longer before it failed. It was observed from the figure that the maximum horizontal deflection of each wall increased with the increased H/t. The maximum horizontal deflection of 18.49 mm was recorded in FCS-F11, which is the most slender wall. General trend of horizontal displacement for FCS-F wall is presented in Fig. 11(b). It shows that the mid height section of wall experienced highest horizontal displacement due to bending. Previous study on effect of H/t towards deflection in a column with different system of reinforcement has also recorded similar finding. Saravanan et al. [47] studied the performance of glass fiber reinforced polymer (GFRP) wrapped high strength concrete (HSC) columns with various slenderness ratios under uni-axial compression. It was found that the axial deflection was recorded higher for more slender columns compared to less slender ones. The relationship of H/t with horizontal deflection of FCS-F walls was further illustrated in Fig. 12.
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Water permeability of foamed concrete

Water permeability of foamed concrete

In this study there are many aspect which has been discussed by the researcher but what is relevant to this study is on the water permeability and compressive strength of the foamed conc[r]

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Applications of foamed lightweight concrete

Applications of foamed lightweight concrete

The primary reason for introducing polymer materials into concrete and cement-based compounds is to improve the physical and mechanical characteristics of the resultant cementitious material to be lightweight, self compacting, high workability, good thermal insulation, and can be cut and nail/screw easily (Koh 2008). One of the important characteristics of lightweight concrete is light or low-density foamed. El-Reedy, 2009 has state the classification of lightweight concrete in Fig. 1.

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GFRP Shear Grid for Precast, Prestressed Concrete Sandwich Wall Panels.

GFRP Shear Grid for Precast, Prestressed Concrete Sandwich Wall Panels.

One of the objectives of the experimental program, discussed in section 3, is to characterize the behavior of the glass fiber reinforced polymer grid/rigid insulation shear transfer mechanism for their use in precast prestressed concrete sandwich panels. It was also to provide a comparison between the effectiveness of using glass fibers in comparison to carbon fibers. Typically, an appropriate amount of shear grid connectors are required in order to fully achieve composite action, allowing for the full moment of inertia to resist induced shear forces from the applied loading. The following section provides comparisons between specimens with glass and carbon FRP grid connectors tested in direct shear. The proposed design equation presented in section 5.2 aims at helping design engineers to calculate the shear flow capacity of the GFRP grid connectors and rigid insulation based on the various parameters believed to affect the behavior. This could allow for structural efficiency and the economic savings of these panels to be realized.
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Use of CFRP Grid as Shear Transfer Mechanism for Precast Concrete Sandwich Wall Panels.

Use of CFRP Grid as Shear Transfer Mechanism for Precast Concrete Sandwich Wall Panels.

The research reported in this thesis summarizes test results and analysis of a comprehensive research program undertaken to study a proposed CGRID/foam system as shear transfer mechanism used in precast concrete sandwich wall panels. All the wall panels were built with three concrete wythes connected with four 6 feet long vertical strips of CGRID along with two layers of rigid foams. Various parameters believed to affect the shear flow strength for this CGRID/foam system were examined by testing one hundred panels. The parameters included: the type of rigid foam, the thickness of rigid foam, and the spacing between the individual vertical lines of CGRID. Test results were used to develop design equations to estimate the shear flow strength and shear modulus for CGRID/rigid foam system as affected by these parameters. A non-linear 3-D finite element analysis was performed using a commercial software utilizing non-linear geometry and non-linear material properties. Research findings based on the test results and analysis can be summarized as follows. 1. Panels produced with EPS and XPS-SB rigid foam developed higher shear strengths in
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Development of Interaction Diagram for Eccentrically Loaded RC Sandwich Walls with Different Design Parameters

Development of Interaction Diagram for Eccentrically Loaded RC Sandwich Walls with Different Design Parameters

Abstract—Sandwich sections have a very complex nature due to variability of behavior of different materials within the section. Cracking, crushing and yielding capacity of constituent materials enforces high complexity of the section. Furthermore, slippage between the different layers adds to the section complex behavior. Conventional methods implemented in current industrial guidelines do not account for the above complexities. Thus, a throughout study is needed to understand the true behavior of the sandwich panels thus, increase the ability to use them effectively and efficiently. The purpose of this paper is to conduct numerical investigation using ANSYS software for the structural behavior of sandwich wall section under eccentric loading. Sandwich walls studied herein are composed of two RC faces, a foam core and linking shear connectors. Faces are modeled using solid elements and reinforcement together with connectors are modeled using link elements. The analysis conducted herein is nonlinear static analysis incorporating material nonlinearity, crashing and crushing of concrete and yielding of steel. The model is validated by comparing it to test results in literature. After validation, the model is used to establish extensive parametric analysis to investigate the effect of three key parameters on the axial force bending moment interaction diagram of the walls. These parameters are the concrete compressive strength, face thickness and number of shear connectors. Furthermore, the results of the parametric study are used to predict a coefficient that links the interaction diagram of a solid wall to that of a sandwich wall. The equation is predicted using the parametric study data and regression analysis. The predicted α was used to construct the interaction diagram of the investigated wall and the results were compared with ANSYS results and showed good agreement.
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results of this investigation were to be considered valid for lightweight concrete, which is the object this investigation. The densities increased with curing ages for both water-cured and air-cured specimens. The increased could be a result of the pore-refining effects that the continued formation of C-S-H gel resulting from hydration has on the matrix of the internal structure. The water-cured specimens however developed higher densities than the air-cured specimens. This might be due to the contribution of pores water, in the matrix of the specimens,to its weight.For structural applications, compressive strength at 28 days of curing is considered to be the index of concrete quality [35]. From the Table 2, it can be observed that the compressive strength at 28 days curing varies from 15.43N/mm 2 to 13.89N/mm 2
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Investigation on Failure Modes of Precast Foamed Sandwich Panels under Punching

Investigation on Failure Modes of Precast Foamed Sandwich Panels under Punching

Precast Concrete Sandwich Panels (PCSP) consists of concrete layers, Insulation layer and Shear connector(SC). However most commonly used insulation layers are Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS). Variety of application comes under sandwich panel. These concrete layers are connected by the means of Shear connector. These panels can be classified into three types i.e., fully composite panels, partially composite panel and non-composite panels [5]. The strength of the panels mainly depends on the material and capacity of the shear connector, Shear connectors also impact the degree of composite action [6]. These panels tends to reduce the density by 10 to 15 percent as compared to the conventional concrete and hence these are less prone to seismic forces [7].
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FRACTURE ENERGY OF FOAMED CONCRETE BY MEANS OF THE THREE-POINT BENDING TESTS ON NOTCHED BEAM SPECIMENS

FRACTURE ENERGY OF FOAMED CONCRETE BY MEANS OF THE THREE-POINT BENDING TESTS ON NOTCHED BEAM SPECIMENS

almost identical, especially for foamed concrete and mortar. Fracture energy using V-notched beam specimens gave slightly higher value around 15% to 25% for foamed concrete and mortar, while approximately 32% for normal concrete. The correspondence of fracture energy proof that the type of notch plays insignificant role. In view that the strength of foamed concrete is mostly governed by the amount of sand, sand-cement ratio and particle size distribution of sand as stated by Ravindra et al. (2005), hence, the fracture energy of foamed concrete is lower than mortar and normal concrete. The present of voids on foamed concrete also reduces the strength, consequently affected the crack resistance. Although the fracture energy of foamed concrete is only around 18N/m to 25N/m, it is indicates relatively high level despite lower compressive strength.
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