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S Y Lai - One of the best experts on this subject based on the ideXlab platform.
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Predicting strength of wood I-Joist with a circular web hole
Journal of Structural Engineering-Asce, 2008Co-Authors: G B Pirzada, Ying Hei Chui, S Y LaiAbstract:Web holes are often made in wood I-Joists to allow passage of services. Design properties of wood I-Joists with a web hole are commonly developed through testing which leads to empirical design information. This paper describes a mechanics-based method to predict the strengths of wood I-Joists with a circular web hole that is suitable for implementation as a design tool. Curved beam theory is used to compute stresses around a hole. Peak tensile stresses obtained from curved beam analysis agree well with those predicted using the finite-element method. Failure load is attained by the application of fracture mechanics based finite area method. The method developed is used to predict failure loads of wood I-Joists of different depths with different web hole sizes. Simplification of the method leads to the development of a simple expression that can be used for engineering design. It is found that the predicted strengths are in a good agreement with the corresponding test results. The calculation method developed can potentially replace the testing approach generally adopted by the wood I-Joist industry.
Ying Hei Chui - One of the best experts on this subject based on the ideXlab platform.
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development of rigging system for prefabricated wood i Joist floor panels
Modular and Offsite Construction (MOC) Summit Proceedings, 2019Co-Authors: Sigong Zhang, Ying Hei Chui, Jeanphilippe Letarte, Luca DalcastagneAbstract:Panelized building construction are highly mechanized. Material handling and lifting equipment dominate construction sites and constitute the critical element in achieving productivity. In recent construction practice, panelized wood I-Joist floor panels are normally lifted into place by mobile crane using flexible slings inserted through the predrilled holes on the I-Joist web and sheathing panels above the I-Joist top flange and then wrapped around the I-Joists at the four corners. However, the pre-drilled holes on the web and sheathing may weaken the floor panels. Moreover, a range of techniques for lifting and handling mass timber panels have been developed. A typical rigging technique consists of a lifting ring and a steel plate with pre-drilled holes. By using several self-tapping screws, the panel was connected with the rigging device for lifting. However, since prefabricated I-Joist floor panels are much lighter than mass timber panels and the I-Joist flange is relatively narrow and thin, the rigging device for mass timber panels cannot be applied directly to I-Joist floor panels, but a modified design can be developed for prefabricated I-Joist floor panels. In the present study, a new rigging device was designed for prefabricated wood I-Joist panels and their load capacity was evaluated by withdrawal tests. Several factors influencing the withdrawal capacity were investigated including screw types and quantities, flange width and materials, and OSB thickness.
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Predicting strength of wood I-Joist with a circular web hole
Journal of Structural Engineering-Asce, 2008Co-Authors: G B Pirzada, Ying Hei Chui, S Y LaiAbstract:Web holes are often made in wood I-Joists to allow passage of services. Design properties of wood I-Joists with a web hole are commonly developed through testing which leads to empirical design information. This paper describes a mechanics-based method to predict the strengths of wood I-Joists with a circular web hole that is suitable for implementation as a design tool. Curved beam theory is used to compute stresses around a hole. Peak tensile stresses obtained from curved beam analysis agree well with those predicted using the finite-element method. Failure load is attained by the application of fracture mechanics based finite area method. The method developed is used to predict failure loads of wood I-Joists of different depths with different web hole sizes. Simplification of the method leads to the development of a simple expression that can be used for engineering design. It is found that the predicted strengths are in a good agreement with the corresponding test results. The calculation method developed can potentially replace the testing approach generally adopted by the wood I-Joist industry.
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Experimental evaluation of wood I-Joists with web holes
Forest Products Journal, 2006Co-Authors: Muhammad T. Afzal, Ying Hei Chui, Shouyong Lai, Ghulam PirzadaAbstract:Prefabricated wood I-Joists are commonly used in wood frame construction. For some applications, web holes are made in wood I-Joists for passage of service ducts, plumbing or wiring. This paper presents an experimental study on wood I-Joists with web holes. Two I-Joist depths with three hole sizes and two web hole shapes (circular and square) were investigated. It was found that a web hole with sharp comers (e.g., square) has a bigger negative impact on strength than a circular hole of a similar size. For a circular hole, the percent reduction in strength is independent of Joist depth. It is shown that the effect of a circular web hole can be considered the same as a square hole that can be inscribed in that circle. The influence of bending moment on failure load was found to be significant for a typical span-to-depth ratio found in service. Based on the results of these tests, further study is recommended to quantify the influence of shear-to-moment ratio on load-carrying capacity of wood I-Joists with a web hole. Results from the tests on I-Joist with two circular web holes with a size of 75 percent web depth showed that the critical clear spacing is about two times the web hole diameter.
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Construction methods for minimizing vibration levels in floors with lumber Joists
Canadian Journal of Civil Engineering, 1992Co-Authors: Ian F. C. Smith, Ying Hei ChuiAbstract:The National Building Code of Canada 1990 specifies the allowable spans for lumber floor Joists that are expected to lead to satisfactory vibrational behaviour. This paper discusses construction methods that improve the floor behaviour once the flooring and Joists appropriate to a particular building occupancy have been selected. Laboratory tests on full-size floors demonstrate that adding between-Joists bridging and supporting all four floor edges significantly improves the overall vibrational performance of wood floors. Bridging consisting of solid blocking glued to the underside of the flooring and a mild steel strap nailed to the underside of blocking and Joists is more effective than several alternative details. Incorporating pads of damping material between flooring and Joists, or at bearings, can have a detrimental effect on floor performance. The use of elastomeric adhesive, in lieu of nailed flooring-to-Joist connections, does not significantly enhance the mechanical performance of floors with lu...
Kenneth J Fridley - One of the best experts on this subject based on the ideXlab platform.
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reliability of wood Joist floor systems with creep
Journal of Structural Engineering-asce, 1995Co-Authors: Timothy A Philpot, David V Rosowsky, Kenneth J FridleyAbstract:Light-frame wood floors are constructed from a number of parallel flexural members (Joists), which provide the primary structural support. Sheathing material is attached across the top edges of these Joists to form the floor surface. Because the Joists are connected in this manner, load sharing occurs, which enhances the performance of the system as a whole. Current design procedures focus on the behavior of single members with only limited provisions account for the improved performance of systems. In this study, the reliability of wood Joist floors is investigated considering both strength and serviceability limit states. The objective of the system reliability analyses is to determine appropriate system factors for use in single member load and resistance factor design checking equations. These factors are included to account for the beneficial effects associated with systems of parallel members. This study considers factors such as lumber species and grade, floor size, and the effects of creep deformations. A stochastic viscoelastic stress-strain relationship is used to model the time-dependent behavior of wood, the stochastic pulse process models are used to account for the temporal variability of the loads. Cumulative damage analysis using two common damage accumulation models is used to account for the time-dependent strength of wood flexural members.
Daniel P. Hindman - One of the best experts on this subject based on the ideXlab platform.
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Inspection of I-Joists in Residential Construction
Practice Periodical on Structural Design and Construction, 2014Co-Authors: John C. Bouldin, Joseph R. Loferski, Daniel P. HindmanAbstract:AbstractI-Joists may be used as floor Joist and roof-rafter members in residential construction but require different installation practices compared with solid-sawn lumber because of I-Joist geometry and design. The building codes in this paper contain clear specifications for the installation of sawn-lumber products. Because I-Joists are proprietary and installation requirements vary by brand, manufacturer literature is incorporated by reference into the building codes discussed herein. The engineered and proprietary nature of I-Joists may be unfamiliar to carpenters and other trade professionals, resulting in installation errors. I-Joist installations that do not comply with manufacturer specifications are considered code violations. Through use of the Delphi method, an expert-validated inspection methodology was developed by interviewing code officials, home inspectors, and engineered-wood-product manufacturers. This paper summarizes the results, including best practices for inspection methods and I-j...
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Bracing of Wood Composite I-Joists to Resist Lateral Buckling from Walking Loads
Journal of Construction Engineering and Management, 2014Co-Authors: Daniel P. Hindman, C. Ryan Bamberg, Maury A. NussbaumAbstract:AbstractLateral buckling of unbraced beams during construction may be an important cause of fatalities and injuries. Temporary bracing to restrict lateral buckling is a potential preventive approach, but has received little study. Lateral acceleration, lateral displacement, and rotation of wood composite I-Joists were measured under different bracing conditions while participants traversed the Joists. Five different bracing stiffnesses and two different bracing placements were examined. Lateral displacement and rotation increased near the midspan of the Joist, while acceleration remained consistent. Greater lateral displacement and rotation were found with increasing participant weight and lack of construction experience. Construction experience was found to be a significant factor in the amount of Joist motion. A safety platform similar to the testing methods discussed may have potential as a training tool to expose workers to partially braced Joists. The relationship of lateral displacement and rotation...
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Mechanical Response of Unbraced Wood Composite I-Joist to Walking Loads
Journal of Construction Engineering and Management, 2013Co-Authors: Daniel P. Hindman, Paul D. Timko, Maury A. NussbaumAbstract:AbstractLateral buckling of unbraced wood composite I-Joists is a form of instability that causes the Joist to deflect laterally and rotate. This instability may be a cause of worker falls and should be explored to understand the range of loading and out-of-plane motion required to cause lateral buckling. While walking on unbraced Joists is uncommon on construction sites, understanding the movement of unbraced Joists is needed to model more commonly observed partially braced Joists. This paper investigated the load and out-of-plane movement of several unbraced wood composite I-Joists subjected to human walking loads. Vertical load at the ends of the Joist, top and bottom horizontal loads at one end of the Joist, as well as lateral deflection and rotation at the midspan and quarter-span were measured while participants traversed the Joist. Lateral buckling of Joists was observed due to walking loads. Total vertical load measured was similar to participant weight, while horizontal loads ranged from 9.6 to 1...
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Cold-Formed Steel Reinforcement for Improperly Cut Wood Composite I-Joists
Practice Periodical on Structural Design and Construction, 2008Co-Authors: Daniel P. Hindman, Joseph R. LoferskiAbstract:Wood composite I-Joists have become an attractive option for floor Joists in residential construction. One disadvantage of I-Joists is the restrictions on hole size and the inability to notch the top compression flange. This technical paper evaluates two cold-formed steel reinforcers to strengthen I-Joists that have been improperly cut—one to reinforce the top flange, and another to reinforce the web. The reinforcers were tested at various locations along the length of the beam. Based upon testing results, the notched I-Joists with the flange reinforcers retained 60.2% of the strength and 77.0% of the stiffness of the original I-Joists. The I-Joists with the web hole and single-sided reinforcers retained 78.2%% of the strength and 95.7% of the stiffness of the original I-Joists. I-Joists with the web hole and the double-sided web reinforcers retained the I-Joist strength and 95.1% of the stiffness of the original I-Joist. These reductions in strength and stiffness can be used to determine if the reinforce...
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Torsional Rigidity of Wood Composite I-Joists
Wood and Fiber Science, 2007Co-Authors: Daniel P. Hindman, Harvey B Manbeck, John J. JanowiakAbstract:The torsional rigidity of I-Joists is useful in determining the lateral torsional buckling of unsupported beams, the stiffness of two-way floor systems, and the natural frequency for wood floors. The torsional rigidity of two I-Joist materials, one manufactured with laminated veneer lumber (LVL) flanges and the other with laminated strand lumber (LSL) flanges, was measured. There were no significant differences in the measured torsional rigidity of the two I-Joist materials. The measured torsional rigidity terms were compared with predictions of torsional rigidity based upon the distinct cross-sectional dimensions and previously measured material elastic constants. A finite element model was used to predict the torsional rigidity of the I-Joist section and to examine the effect of isotropic and orthotropic assumptions. An isotropic torsional rigidity prediction using G 12 values of the web material and G 13 values of the flange materials provided agreement with the measured 95% confidence intervals for both I-Joist materials. Prediction of torsional rigidity was heavily influenced by the planar shear moduli in the larger cross-sectional dimension. The use of an assumed E:G ratio of 16:1 for all wood materials overpredicted the torsional rigidity values by 30% compared to more refined predictions.
G B Pirzada - One of the best experts on this subject based on the ideXlab platform.
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Predicting strength of wood I-Joist with a circular web hole
Journal of Structural Engineering-Asce, 2008Co-Authors: G B Pirzada, Ying Hei Chui, S Y LaiAbstract:Web holes are often made in wood I-Joists to allow passage of services. Design properties of wood I-Joists with a web hole are commonly developed through testing which leads to empirical design information. This paper describes a mechanics-based method to predict the strengths of wood I-Joists with a circular web hole that is suitable for implementation as a design tool. Curved beam theory is used to compute stresses around a hole. Peak tensile stresses obtained from curved beam analysis agree well with those predicted using the finite-element method. Failure load is attained by the application of fracture mechanics based finite area method. The method developed is used to predict failure loads of wood I-Joists of different depths with different web hole sizes. Simplification of the method leads to the development of a simple expression that can be used for engineering design. It is found that the predicted strengths are in a good agreement with the corresponding test results. The calculation method developed can potentially replace the testing approach generally adopted by the wood I-Joist industry.
