Principles of Mechanics Model for Wood Structural Panel Portal Frames

Abstract

A principles of mechanics model to predict the strength of wood structural panel portal frames has been developed. The wood structural panel portal frame consists of a wood structural panel overlapping a header to form a moment resisting connection to resist in-plane lateral loads. The advantage of portal frames is that they can resist relatively high lateral loads for a small wall width. The model is based on moment couples and shear strength of the components. Model predictions are compared to test results for a variety of portal frame constructions that have been tested. All portal frame walls were tested with the SEAOSC [1996] SPD cyclic load protocol for in-plane shear resistance. Portal frame constructions investigated in this study range from 16 to 24-inch wide, 8 to 10-ft tall, sheathed with OSB or plywood, and with and without hold down devices at the base of the wall segment. Also investigated are portal frames built on raised wood floor assemblies with variable base of wall restraint configurations which are modeled with moment couples. The model is compared to ten unique portal frame constructions that were tested. Comparing the model to the test results shows that the model accurately predicts the strength to within about 5% on average. OVERVIEW This report presents a principles of mechanics model to predict the in-plane lateral racking strength, V, of a wood structural panel portal frame design. The general theory is as follows by Equations 1-3 and Figure 1: V = Minimum of: V moment couples , V shear strength (1) V moment couples = (M top + M bottom) / H (2) V shear strength = Minimum of: v panel , v nails , v base connection (3)

Environmental Impact Assessment of Light-Frame and Timber Frame Structures

“…These components include the beams that support the 2nd floor and the columns that centrally support these beams. Additionally, where available shear wall area on the gable end with garage door openings was deemed insufficient by the IRC, a moment-resisting portal frame was engineered (Martin et al 2008). Figure 6 is a Google Sketch-Up rendering of the standard LF structure (Google 2012).…”

Gravity and Wind Load Path Analysis of a Light-Frame and a Traditional Timber Frame Building

“…These components include the beams that support the floor and the columns that centrally support these beams. Additionally, where available shear wall area on the gable end with garage door openings was deemed insufficient by the IRC for lateral force resistance, a moment-resisting portal frame was engineered following the guidelines published by Martin et al (2008). Fig.…”

“…Because of the limitations of the IRC (ICC 2009), sufficient shear wall area was not available on the gable end of the LF structure due to the garage doors. A portal frame was designed for the necessary lateral force resistance of this wall (Martin et al 2008). Because of the structural differences and increased stiffness of this momentresisting frame per unit of sheathing area, a separate stiffness calibration method was necessary.…”