Light-frame Wood Shear Walls Research Articles

Seismic performance of multi-story glulam post-and-beam structures reinforced with knee-braces

The glulam post-and-beam structure reinforced by knee-braces is a promising option for multi-story buildings with a compromise between architectonical space and lateral resistance. In this study, four glulam knee-braced frame structures with different heights (i.e., 3-story, 5-story, 6-story, and 9-story structures) were designed as the prototype buildings. Then, nonlinear numerical models were carefully established, and the crucial component behavior in the structure was calibrated by experimental results. Fifty mainshock earthquake records and mainshock-aftershock earthquake records were selected as the excitations for the nonlinear dynamic numerical simulation. The maximum inter-story drift (MaxISDR) and the residual inter-story drift (ResISDR) were obtained. The seismic performance of these prototype buildings was subsequently evaluated based on probabilistic seismic demand analysis (PSDA). The analytical results show that the glulam knee-braced frame structures have a desirable seismic performance due to the ductility of the connections and the knee braces. However, for the glulam knee-braced frame structures that exceed six stories, it is recommended to use additional reinforcing systems (i.e., diagonal braces or infill light-frame wood shear walls) to avoid premature damage of the knee braces and to increase the lateral stiffness of the structure. The presented seismic performance evaluation in this paper can be used as a reference for the development of seismic design guidelines for glulam knee-braced frame structures.

Numerical assessment of lateral deflection equation of single-storey light-frame wood shear walls

Based on the decomposition of the deflection into bending, panel shear, nail slip, and base rotation terms, the nonlinear four-term equation specified by the Canadian wood design code provides an estimate of the total lateral deflection of light-frame wood shear walls. This paper reports the creation of a numerical procedure for separating the responses for each term using a detailed nonlinear finite element modeling (FEM) that simulates individual components of shear walls. Since sheathing panel stiffness is not considered in computations of the bending term, the study reveals that bending deformation results calculated using the equation are more conservative than the FEM results. The nail slip term does not reflect the real nail base connection properties. A new equilibrium equation for determining the lateral deflection due to base rotation is presented. The equation is generally conservative because of the omission of some practical considerations.

Structural characteristics of light-frame wood shear walls with various construction detailing

A total of 26 full-scale walls were investigated with the aim to study the effects of construction details variation on the behavior of the shear walls. The deflected shape of the end studs was found to be non-linear with regard to loading level. The bending component seems affected by the rotation of the sheathing panels and nail slip. No significant panel shear deformation was observed. The deflection expression in the wood design standard was found to under-estimate the nail slip component. Hold-down system used in this study behaved in a non-linear manner with higher initial stiffness than that assumed in design. The strength and stiffness correlated almost directly to the inverse of the wall aspect ratios, with no clear trends found on ductility. Walls with aspect ratios not permitted according to the wood design standard followed similar strength and stiffness trends and had sufficient ductility ratios as those with lower aspect ratios. Adding more end studs and changing the size of the studs had no significant effect on the overall wall capacity and little effect on its stiffness. The wall strength was significantly affected by the nail diameter and nail spacing, but this effect was not linear. The study also showed that having continuous hold-down connections has a positive effect on the capacity, stiffness and ductility of the wall. Having no hold-down adversely affected the wall capacity and stiffness. A shear wall model was developed and the results from the model were compared with those obtained experimentally. It was found that the model was capable of predicting the wall behaviour with reasonable accuracy.

Nonlinear Numerical Model of Post-Tensioned Elastic Rocking Panels for Application in Building Structural Analysis

This paper presents a new 4-node finite element model, developed from a 2-node rocking beam element that can predict the rocking behavior of post-tensioned panels and columns. The stiffness matrix of the 2-node beam element was derived from the flexibility method. Then, the stiffness matrix of the 4-node beam element was obtained through the use of transformation matrices. The 4-node element model allows for the prediction of not only the global behavior of the rocking element (e.g., nodal displacements and nodal loads) but also the local behavior (e.g., the contact length, the vertical displacement, and the strain and stress at the rocking interface). The numerical results from the 4-node element model were compared to that from 3D finite element method (FEM) models in MATLAB 2016 and ABAQUS programs and showed a high accuracy. Moreover, the 4-node element model can be combined with the other types of elements in order to analyze building structures at a global level, especially for mid-rise and tall buildings where the nodal displacements at panel corners are vital to correctly predict the behavior of the other structural elements (e.g., light-frame shear wall elements). An example of a six-story building that included a hybrid system of post-tensioned cross-laminated timber (CLT) walls and light-frame wood shear walls was presented.

Seismic assessment of a three-story wood building with an integrated CLT-lightframe system using RTHS

This paper presents the results of an experimental study whose objective was to investigate the behavior of a hybrid wood shear-wall system defined herein as a combination of traditional light-frame wood shear walls with post-tensioned rocking Cross-Laminated Timber (CLT) panels. The post-tensioned CLT panels in the hybrid system offer both vertical and lateral load resistance and self-centering capacities. The traditional Light-Frame Wood Systems (LiFS) provide additional lateral load resistance along with a large amount of energy dissipation through the friction of nail connections. Thus, a combination of these two types of structures, in which traditional light-frame wood shearwalls are utilized as structural partition walls, may provide an excellent structural solution for mid-rise to tall wood buildings for apartments/condos, where there is a need for resisting large lateral and vertical loads as well as structural stability. In this study, a real-time hybrid testing algorithm using a combination of time-delay updating and Newmark-Beta feed forward to reduce the undesirable effects of time delay was introduced. The top two-stories of a three-story building were modeled as a numerical substructure with the first story as the experimental CLT-LiFS substructure. The experimental results of the hybrid wall are presented and discussed in this paper.

Testing and analytical modelling of intermediate gypsum wallboard in wood shear wall sheathing to framing connections

Light frame wood shear walls resist lateral loads primarily through the individual nailed connections between the sheathing and framing. The most common arrangement for such shear walls is to have sheathing on one side and gypsum board on the other. In various situations it can be desirable to increase the capacity of this type of walls by fastening a layer of sheathing overtop of the drywall. This study considered the effect that an intermediate layer of gypsum has on the strength of nailed connections in shear walls, while maintaining code-defined minimum nail penetrations. Results show that intermediate gypsum placed between the sheathing and framing resulted in significantly reduced capacity and stiffness. Analytical modelling showed good correlation with experimental results. The implications of the experimental testing and modelling are that code provisions allowing the use of intermediate gypsum wallboard should not be relied upon.

Hybrid System of Unbonded Post-Tensioned CLT Panels and Light-Frame Wood Shear Walls

Cross-laminated timber (CLT) is a relatively new type of massive timber system that has shown to possess excellent mechanical properties and structural behavior in building construction. When post-tensioned with high-strength tendons, CLT panels perform well under cyclic loadings because of two key characteristics: their rocking behavior and self-centering capacity. Although post-tensioned rocking CLT panels can carry heavy gravity loads, resist lateral loads, and self-center after a seismic event, they are heavy and form a pinched hysteresis, thereby limiting energy dissipation. Conversely, conventional light-frame wood shear walls (LiFS) provide a large amount of energy dissipation from fastener slip and, as their name implies, are lightweight, thereby reducing inertial forces during earthquakes. The combination of these different lateral behaviors can help improve the performance of buildings during strong ground shaking, but issues of deformation compatibility exist. This study presents the results of a numerical study to examine the behavior of post-tensioned CLT walls under cyclic loadings. A well-known 10-parameter model was applied to simulate the performance of a CLT-LiFS hybrid system. The post-tensioned CLT wall model was designed on the basis of a modified monolithic beam analogy that was originally developed for precast concrete-jointed ductile connections. Several tests on post-tensioned CLT panels and hybrid walls were implemented at the Large Scale Structural Lab at the University of Alabama to validate the numerical model, and the results showed very good agreement with the numerical model. Finally, incremental dynamic analysis on system level models was compared with conventional light-frame wood system models.

Nailed Connection Behavior in Light-Frame Wood Shear Walls with an Intermediate Layer of Insulation

AbstractThe shear strength and stiffness of light-frame wood shear walls is highly dependent on the behavior of their individual nailed connections. Eighty-four nailed connection specimens were tested under shear loading to determine the effect of including rigid insulation as an intermediate material between the sheathing and framing elements in a light-frame wood shear wall. Each specimen contained common 10d or 16d nails, 15.9 mm oriented strandboard sheathing, spruce-pine-fir lumber, and rigid insulation in varied thicknesses between 0 and 38.1 mm. From the load-deformation results, maximum load, yield load, and stiffness were assessed using curve-fitting and yield-point determination methods. The results indicate that, as the insulation thickness increases, the connection strength and stiffness both exhibit a steep reduction. In addition, nonlinear two-dimensional (2D) finite-element models of the same nailed connections were developed. These models showed good correlation with experimental data and ...

Contribution of Type-X Gypsum Wall Board to the Racking Performance of Light-Frame Wood Shear Walls

AbstractThis paper presents an experimental investigation of the racking performance of light-frame wood shear walls to evaluate the effect of Type X gypsum wall board (GWB). Twelve shear walls she...

Shear Load Performance Test in Accordance with Sheathing Materials of Shear Wall

In this study, the light-frame wood shear walls according to the sheathing materials was carried out to investigate the shear load performance. Most common sheathing materials are the structural OSB and gypsum board used to consist wall of wood-frame house. Seven different type of specimens are composed of several sheathing materials and shear test was taken to evaluate shear performance by KS F 2154. As a result, shear walls(G12.5/G12.5 and G12.5/OSB) show that maximum shear strength and shear rigidity modulus are 7316N/mm118.25 N/mm and 11129 N/mm184.66 N/mm respectively. The shear wall using gypsum board 15mm improve maximum shear strength and shear rigidity modulus about 30%. The shear wall using 15mm gypsum board showed intermediate value in one side specimens. Different types of shear walls could be compared with the shear load performance. Also, nailed joint failure aspects are different to sheathing material and installing method.