Development of creep model for structural insulated timber-foam panels used as basement walls under sustained soil pressure in residential buildings (original) (raw)
Related papers
Flexural Creep Effects on Permanent Wood Foundation Made of Structural Insulated Foam-Timber Panels
CSCE 3rd International Structural Specialty Conference, 2012
The structural insulated panel (SIP) is an engineered composite product composed of an insulating foam core sandwiched to provide the insulation and rigidity, and two face-skin materials to provide durability and strength. SIPs can also be used as permanent wood foundation (PWF) for basements in low-rise residential construction to save in the energy cost. The maximum deflection equation specified in the Canadian Standard for Engineering Design of Wood, CAN/CSA-O86.09 specifies expressions for the effects of short-term bending deflection on the PWF timber stud walls. PWF is subjected to gravity loads associated with lateral soil pressure. To use the available combined bending and axial compression equation for PWF design, it was observed that the soil pressure would cause short-term and long-term flexural creep deflection of the wall that would decrease the wall capacity. Information on the long-term creep behaviour of SIPs under sustained triangular loading, simulating soil pressure, is as yet unavailable. As such, this paper presents a summary of flexural creep tests conducted to determine the increase in SIP deflection under soil pressure over a period of eight months. Using the experimental data, the available mathematical and mechanical creep models were evaluated to predict the flexural creep constant (K) of SIP foundation wall subjected to soil pressure over a service life up to 75 years. A flexural creep constant was then proposed to determine the long-term eccentricity of gravity loading in the available combined bending and axial compression equation for PWF design.
2011
A Permanent Wood Foundation (PWF) is a panel composed of expanded polystyrene insulation and preserved stud cores laminated between oriented-strand boards and preserved plywood. This thesis presents the experimental testing on selected PWFs' sizes to investigate their long-term creep behaviour under sustained soil pressure. The long-term creep tests were performed over eight months, followed by loading the tested panels to destruction to determine their axial compressive strength. The ultimate load test results showed that the structural qualification of PWF is "as good as" the structural capacity of the conventional wood-frame buildings. The obtained experimental ultimate compressive resistance and flexural resistance, along with the developed long-term creep deflection of the wall under lateral soil pressure can be used in the available Canadian Wood Council (CWC) force-moment interaction equation to establish design tables of such wall panels under gravity loading and soil pressure.
Effect of Temperature and Relative Humidity on Creep Deflection for Permanent Wood Foundation Panels
CSCE 3rd Specialty Conference on Material Engineering & Applied Mechanics, 2013
The structural insulated panel is an engineered composite product composed of an insulating foam core sandwiched to provide the insulation and rigidity, and two face-skin materials to provide durability and strength. SIPs can also be used as permanent wood foundation (PWF) for basements in low-rise residential construction to save in the energy cost. The maximum deflection equation specified in the Canadian Standard for Engineering Design of Wood, CAN/CSA-O86.09 specifies expressions for the effects of short-term bending deflection on the PWF timber stud walls. Information on the long-term creep behavior of SIPs under sustained triangular loading, simulating soil pressure, including effect of the change in ambient temperature and relative humidity is as yet unavailable. The long-term creep deflection for permanent wood foundation panels that is characterized as viscoelastic materials is highly affected by the change in ambient temperature and relative humidity. This paper reported the results from flexural creep experiments performed on two sets of different sizes of PWF made of structural-insulated foam-timber panels. In these tests, deflection, temperature and relative humidity were tracked for an eight-month period. The experimental findings were examined against existing creep models in the literature. Then, a creep model incorporating the effects of temperature and relative humidity on creep deflection was developed. Correlation between the proposed model and the experimental findings provides confidence of using the proposed model in the determination of the capacity of the PWF under combined gravity loading and sustained soil pressure.
2010
A Structural Insulated Panel (SIP) is a panel composed of foam insulation core laminated between two oriented-strand boards (OSB). SIPs deliver building efficiencies by replacing several components of traditional residential and commercial construction, including: (i) studs; (ii) insulation; (iii) vapour barrier; and (iv) air barrier. A SIP-based structure offers superior insulation, exceptional strength, and fast installation. Besides those benefits, the total construction costs are less with SIPs compared to wood-framed homes, especially when considering speed of construction, less expensive HVAC equipment required, reduced site waste, reduction construction financing costs, more favorable energy-efficient mortgages available, and the lower cost of owning a home built with SIPs. This paper presents a summary of the experimental testing on selected SIP sizes to investigate their long-term flexural creep behavior under sustained triangular loading. The subject panels are proposed to be used as basement walls in residential construction where the walls carry the gravity loading from the building in addition to lateral soil pressure. Two SIP sizes were considered in this study, 2.7 m and 3.0 m height, respectively, with 1200 width and 210 mm thick. The experiment study performed in a manner to comply with applicable ASTM test methods and Canadian Codes. It should be noted that the long-term creep tests were performed over nine months and resulted to determine the increase in panel total deflection with time. The long-term creep test results led to an empirical creep constant that can be used to obtain the long-term deflection over a specified period of time.
Structural behaviour of insulated foam-timber panels under gravity and lateral loading
2021
A Structural Insulated Panel (SIP) is a structural element of expanded polystyrene insulation (EPS) core sandwiched between two oriented-strand boards (OSB). This research proposes SIPs in low-rise residential construction (i.e. houses and low-residential building), replacing the traditional conventional joist floors and stud walls. This research investigates (i) developing expressions for flexural, compression, monotonic racking and cyclic lateral load capacities of SIPs as compared to the joist/stud wall construction. In this study, the proposed design of SIPs was based on (i) generally established theory for analysis, (ii) assessment of full-scale SIP panels by a loading tester, and (iii) computer modeling using the finite-element modeling. The research program included (i) testing SIP walls in axial compression and bending, (ii) racking and cyclic testing on SIP shear walls, (iii) development of finite-element computer models of the tested SIP panels and verifying those using ex...
The First International Symposium on Jointless & Sustainable Bridges
The structural insulated panel (SIP) is a sandwich structured composite that is prefabricated by attaching a lightweight thick core made of Expanded Polystyrene (EPS) foam laminated between two thin, and stiff face skins made of Oriented Strand Board (OSB). The use of sandwich panels provides key benefits over conventional materials including: very low weight; high stiffness; durability and; production and construction cost savings. The facing skins of the sandwich panel can be considered as the flanges for the I-beam carrying bending stresses in which one face skin is subjected to tension, and the other is in compression. The core resists the shear loads and stabilizes the skin faces together giving uniformly stiffened panel. OSB is wood product that shrinks when dry and swells when adsorb moisture either due to liquid or vapor from the surrounding atmosphere. The relative combination of relative humidity and temperature is introduced into the equilibrium moisture content (EMC) that increases with the increase of the relative humidity and with decreasing temperature. Experimental test matrix includes testing 2.44 m (8’) and 4.88 m (16’) long SIPs for 5 years under different sustained loads and weather resistive barriers (WRBs), recording creep deflection, relative humidity and temperature. After creep recovery, the SIPs are loaded to-collapse to determine their flexural strength.
2016
The structural insulated panel (SIP) is a sandwich structured composite that is prefabricated by attaching a lightweight thick core made of Expanded Polystyrene (EPS) foam laminated between two thin, and stiff face skins made of Oriented Strand Board (OSB). The use of sandwich panels provides key benefits over conventional materials including: very low weight; high stiffness; durability and; production and construction cost savings. The facing skins of the sandwich panel can be considered as the flanges for the I-beam carrying bending stresses in which one face skin is subjected to tension, and the other is in compression. The core resists the shear loads and stabilizes the skin faces together giving uniformly stiffened panel. OSB is wood product that shrinks when dry and swells when adsorb moisture either due to liquid or vapor from the surrounding atmosphere. The relative combination of relative humidity and temperature is introduced into the equilibrium moisture content (EMC) tha...
Experimental study on the flexural behavior of structural insulated sandwich timber panels
2021
A series of flexural test and creep tests were conducted on 53 OSB structural insulated sandwich timber panels to predict their behavior when subjected to gravity loading when used in residential and low rise nonresidential buildings. The experiments were designed and performed to test full-scale panels for roof and floor residential construction. The structural adequacy of the developed sandwich panel system is investigated with respect to the effectiveness of the foam core in providing composite action required to meet both strength and serviceability limit-state design reruirements per Canadian Standards for timber design. Strength requirements included flexure and shear, while serviceability check included limiting deflection under operating conditions as well as creep performance under sustained loading. Results from experimental testing were used to draw conclusions with respect the structural qualifications for these SIPs to be "as good as" the structural capacity o...
Seismic Evaluation of Structural Insulated Panels in Comparison with Wood-Frame Panels
Buildings, 2014
Structural Insulated Panel (SIP) wall systems have been used in residential and light commercial buildings for the past sixty years. Lack of sufficient published research on racking load performance and limited understanding of the influence of fastener types on seismic response has been a deterrent in widespread use of the wall system in seismically active areas. This paper presents the results of a study involving a total of twenty one 2.4 m × 2.4 m shear walls tested under monotonic and cyclic loading. Four different 114 mm thick SIP panel configurations and one traditional wood frame wall were tested under monotonic loading according to ASTM E 564-06; and thirteen 114 mm thick SIP panels and three wood frame walls were tested under the CUREE loading protocol according to ASTM E 2126-11. Parameters such as fastener type; spline design; hold-down anchor location; and sheathing bearing were adjusted throughout the testing in order to determine their effects on the SIP's performance. Performance parameters such as peak load and displacement; energy dissipation; allowable drift load capacity and seismic compatibility were determined for all of the specimens. Such parameters were then used to demonstrate the SIP walls' compatibility with the wood frame walls and to determine the efficiency of the different SIP wall configuration and spline systems employed.
Creep Behavior of Structural Insulated Panels (SIPS): Results from a Pilot Study
2014
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