Flexural Creep Effects on Permanent Wood Foundation Made of Structural Insulated Foam-Timber Panels

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.

Reference:

Sayed-Ahmed, M.; Sennah, K. (2012). Flexural Creep Effects on Permanent Wood Foundation Made of Structural Insulated Foam-Timber Panels. 3^rd International Structural Speciality Conference, Edmonton, June 6-9. ISBN: 978-1-894662-18-5, Vol. 3, pp. 1892-1901. 

Statistical Modelling and Prediction of Compressive Strength of Concrete

The matrix mixture of concrete can be made to have high compressive strength. In the present paper, statistical model was built-up to predict the compressive strength of concrete containing different matrix mixtures at fixed age or at different age of 1, 3, 7, 28, 56, 90 and 180 days. The model examines eight different parameters for the matrix mixture that includes: time, water, cement, metakaolin (MK), silica fume (SF), sand (S), aggregate (A) and superplasticizer (SP). This research addresses the effect of the matrix mixture of concrete on the compressive strength, where this information will help the cement industry in producing the required concrete strength. The results from the predicted model have high correlation to the experimental results for the concrete compressive strength.

Reference:

Sayed-Ahmed, M. (2012). Statistical Modelling and Prediction of Compressive Strength of Concrete. Concrete Research Letters, ISSN: 2180-1371, Vol. 3, Issue 2, pp. 452-458.

Flexural Creep Effects on Permanent Wood Foundation made of Structural Insulated Foam-Timber Panels (M.A.Sc. Thesis Abstract)

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 behavior 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.

Library link

http://catalogue.library.ryerson.ca/record=b2123488

Reference:

Sayed-Ahmed, M. (2011). Flexural Creep Effects on Permanent Wood Foundation Made of Structural Insulated Foam-Timber Panels, M.A.Sc. Thesis. Ryerson University, Toronto.

Bridge deck-guardrail anchorage detailing for sustainable construction

A GFRP bar bent was recently developed to overcome the problems of tensile stress reduction at the bent. It is made of corrugated plastic tube formed with required shape of the bent. The tube is then filled with GFRP material in liquid conditions and left to dry.This developed GFRP bent was proposed to be used in one of the new bridges in Ontario.This paper investigates the use of GFRP bar bents as stirrups at the joint between the steel post of the bridge guard-rail system with the deck slab cantilever. In addition, GFRP barswith headed ends are utilized for better anchorage at the post-deck slab joint. Two full scale cantilever post specimens were erected and tested to-collapse. The first specimen cantilever was reinforced with reinforcing steel bars, while the second one was reinforced with GFRP straight bars, bent bars and those with headed ends as applicable locations. Results showed that GFRP-reinforced specimen is as good as that reinforced with steel bars. All specimens failed due to excessive torsional-shear cracks at the post-curb junction, resulting in spalling of the concrete cover at the outer face of the curb at the steel post location.

Reference:

Sennah, K.; Nikravan, N.; Louie, J.; Hassan, A.; Al-Bayati, N; El-Sayed-M; Sayed-Ahmed, M.(2011). Bridge Deck-guardrail Anchorage Detailing for Sustainable Construction. CDCC - The Fourth International Conference on Durability & Sustainability of Fibre Reinforced Polymer (FRP) Composite for Construction and Rehabilitation. ISBN: 978-2-7622-0196-3, pp. 337-334.

Mahmoud Sayed Ahmed
PhD Civil Engineering Candidate
Yeates School of Graduate Studies

Ryerson University

mahmoudsayedahmed.blogspot.ca

Rockfall Bolting and Barrier Protection Systems and Procedures

Rockfall bolting, barrier structure and protection system is geo-structural topic; the aim of it is to serve and protect the community from life risk, economic loss and environmental implications.Rock hazard vector and rock stabilizing systems becomes necessary to protect nearby residential areas, transportation and roads. Rock bolting is the primary protection system resisting static pressure, and rockfall barrier is the secondary protection system resisting dynamic avalanche pressure from 75 kJ up to 5000 kJ (16,200 kg). The selection for the primary or secondary active protection system depends on location and the magnitude of the hazardous of rock stabilizing phenomena.The primary protection system; active or passive post-tensioning system is used as rock bolting.It depends on skin friction of grout-to-soil and bond length of the anchor. The initial transfer force at lock-off shall not exceed 70% from the Minimum Ultimate Strength.The secondary protection system to stabilize the surface uses high-tensile wire mesh or wire cloth screen mesh with strength of individual retaining wire-rope more than 1,770 N/mm2. It can retain up to 38 m3 per meter barrier length (recently increased). Such system allows for hydro-seeding and planting.Rockfall barrier structure can serve better when regularly checked, and maintained. Different protection levels can be used as third level using soldier beams and fourth level as mat foundation. Additional protection systems are used as grouting, and slope geometry

Ground Anchor, FHWA

Reference:

Shaaban, M. (2010). Rockfall Bolting and Barrier Protection Systems.  Journal of Al-Azhar University Engineering Sector, JAUES, ISSN 1110-6409, Vol. 5, Issue 1, pp. 736-747. 

Development of creep model for structural insulated timber-foam panels used as basement walls under sustained soil pressure in residential buildings

A Stressed-Skinned Structural made of a wood-composite panel with foam insulation core laminated between two oriented-strand boards of 7/16” thickness , are called Structural Insulated Panel if OSB are in both faces, and Permanent Wood Foundation if one face contains preserved Plywood of 5/8” thickness, SIPs /PWF Foundation SIPs deliver building efficiencies by replacing several components of traditional residential and commercial construction. ..... Two PWFs sizes were considered in this study, 9’ and 10’ height, respectively, with 4’ width and approx ± 230 mm thick. The experiment study performed in a manner to comply with applicable ASTM test methods and Canadian Codes for Limit State Design. It should be noted that the long-term creep tests were performed over a nine months, followed by loading the tested panels to destruction. The long-term creep test results established 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. 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 loading as well as the long term deflection of the wall under lateral soil pressure / Equivalent Fluid Pressure (EFP) will be used in the force-moment interaction equation to establish the design tables of such wall panels under gravity loading and soil pressure.

PWF; Permanent Wood Foundation	SIP; Structural Insulated Pane

Reference:

Sayed-Ahmed, M.; Shehata, E.; Sennah, K.  (2010). Development of Creep Model for Structural Insulated Timber-Foam Sandwich Walls under Sustained Soil Pressure in Basements of Residential Buildings. Journal of Al-Azhar University Engineering Sector, JAUES, ISSN 1110-6409, Vol. 5, Issue 1, pp. 603-614.