Wood Frame Shear Walls Research Articles

Behavior of Cellulosic Fiber Board Wood-Frame Shear Walls with and without Openings under Cyclical Loading

Behavior of Cellulosic Fiber Board Wood-Frame Shear Walls with and without Openings under Cyclical Loading

The effect of combined use of plybamboo sheathings and self-tapping screws in enhancing wood-frame shear wall performance

ABSTRACT Plybamboo panels are renewable and eco-friendly structural panels with high strength, good dimensional stability, and affordability, making them highly suitable for wood-frame construction. This study presents an experimental investigation of the wood-frame shear wall constructed with plybamboo-sheathing panels with self-tapping screws (STSs) subjected to monotonic and cyclic loadings. Performance parameters including shear strength, elastic shear modulus, ductility ratio, stiffness degradation, and energy dissipation were evaluated. Results indicate that the combined use of plybamboo sheathings and STSs can substantially reduce failures due to the tearing of sheathing, fastener head pull-through, and fastener withdrawal. The plybamboo-sheathed wood-frame shear walls with STSs had over 1.8 times shear strength and 1.4 times ultimate displacement than those of comparable wood-frame shear walls with nails, respectively, maintaining over 80% of their maximum lateral load capacity at a drift level over 4%. Moreover, the influence of aspect ratio and screw spacing on the elastic shear modulus, shear strength, and stiffness degradation of the plybamboo-sheathed wood-frame shear walls with STSs are consistent with those for common wood-frame shear walls.

Lateral behavior of wood frame shear wall using PVC wood-plastic composite (WPC) veneer panels

With the growing awareness of environmental protection and green ecology, there has been significant attention on the utilization of new energy-saving and environmentally friendly materials in building structures. This article proposes a novel structure for PVC wood-plastic composite wall panels. The structure comprises Polyvinyl Chloride (PVC) wood-plastic composite materials as the facing panel and SPF (Spruce-Pine-Fir) dimensional lumber as the wall framework, connected using self-tapping screws. In this study, two standard composite wall panel specimens were subjected to testing using both monotonic loading and low-cycle reciprocating loading methods. Finite element models of the composite wall panels were created using ANSYS Workbench software for analysis, investigating the lateral performance of PVC wood-plastic composite wall panels. The analysis results indicate that PVC wood-plastic composite wall panels exhibit favorable shear strength, elastic lateral stiffness, and lateral deformation as shear walls. The shear wall model can be accurately represented in finite element software, with minimal discrepancy between experimental and finite element analysis results. Consequently, the utilization of PVC wood-plastic composite wall panels as shear walls holds promise for future applications in the structural field.

Effect of Biodeterioration on Modeling Parameters of Code-Compliant Cross-Laminated Timber Lateral Connections

Abstract The effect of biodeterioration on the structural connection performance of timber for conventional framing and mass timber has been investigated recently, but there is a need for additional data as well as for the development of analytical models to utilize these data. An empirical material model (seismic analysis of wood frame shear walls) was fitted to cyclic connection test data of four species of cross-laminated timber at different levels of biodeterioration by two brown-rot fungi. These model inputs were then analyzed to account for trends between wood species and fungal species. Weak trends were most prominent for initial stiffness, intercept load, and displacement at peak force. Correlations were poor with postyield and postpeak stiffness modifiers. These relationships were consistent both as a function of time and as a function of mass loss, but additional data are needed to more accurately predict the effects. The limited relationships likely reflect the variations in fungal decay across the test members.

Shaking table test of a timber building equipped with a novel cost-effective, impact-resilient seismic isolation system

In most cases, construction of Light Frame Timber Buildings (LFTBs) in areas of high seismic hazard requires strong wood frame shear walls and continuous rod systems, which increases the cost of LFTBs. Frictional seismic isolation might be applied to protect LFTBs against extreme ground motions and mitigate the cost of continuous rod systems. However, there are no experimental studies on the response of LFTBs equipped with frictional isolation and subjected to extreme seismic ground motions that might cause impacts between the slider and the perimetral ring or between the isolated base and the perimetral moat wall.This study explores the potential of using impact-resilient frictional isolators as a feasible solution to alleviate stiffening and overturning costs of LFTBs while making them resilient to impacts in case of extreme events. This issue has been researched by evaluating the response of a 1:2 scaled 3-story LFTB isolated with a novel Impact Resilient Double Concave Frictional Pendulum recently developed by the authors. The specimen was subjected to a suite of shaking table tests (white noise, harmonics signals, and seismic records), including strong ground motions such as the Concepcion record (2010 Maule, Chile earthquake, Mw = 8.8) scaled to 130 %. Results indicate that despite being subjected to extreme excitations, peak acceleration ratios (i.e., the ratio of peak floor acceleration to peak ground acceleration) did not exceed 0.75, and story drift ratios were smaller than 0.52 % in most cases. Thus, the superstructure remained in the elastic range without damage. The study demonstrates the potential of achieving effective seismic protection of LFTBs using Impact Resilient devices. In addition, this paper presents a numerical model developed with experimental data, which provides insight into modeling issues such as, for instance, damping properties.

Simulation calculation and analysis of building energy consumption of multi-story glued laminated timber structures

As the only renewable building material, wood has a strong carbon sequestration effect. Thus, timber structures have the natural advantages of saving energy and reducing emissions. Currently, the research objects of building energy consumption are rarely timber structures. To further control the operational energy consumption of timber structures, this paper takes six-story glued laminated timber beam-column frame and light wood-frame shear wall structures as the research objects. Building energy consumption research is conducted through testing the heat transfer coefficient of the envelope structure, air circulation ratio, and Building Information Modeling (BIM) technology on-site. The results show that the energy consumption of the building is consistent with the current energy consumption of small- and medium-sized office buildings, and the heat gain and loss of the building are mainly due to solar radiation and heat conduction of the envelope, respectively. The airtightness of the building has the greatest influence on the energy consumption of the building, and the type of building structure and window-to-wall ratio have little influence on the energy consumption of the building.

Physics-based probabilistic capacity models and fragility estimates for light wood frame shear walls

Light wood frame buildings are common in the United States, and due to their prevalence, there has been significant damage to this type of building in previous earthquakes. For this building type, shear walls (typically sheathed with oriented strand board) are the main lateral force-resisting element. Probabilistic models and fragility estimates incorporating the prevailing uncertainties for shear walls are needed to make accurate predictions of the effects of future earthquakes on buildings of this type. This paper uses experimental data to develop probabilistic capacity models for the shear force and drift of light wood frame shear walls at the yield, peak, and ultimate performance levels. The proposed models are applicable to shear walls in low-rise buildings where the shear deformation is dominant. Moreover, the proposed models are applicable to walls that are similar to walls in the dataset. The probabilistic models are constructed starting from deterministic models. For the shear force, a new deterministic model is proposed. This model predicts the shear force capacity of the wall based on the capacity of individual nails. For drift, existing deterministic drift limits are used. The deterministic models are then improved by incorporating the effect of additional physical characteristics through explanatory basis functions that are shown to be significant in a probabilistic model selection procedure. Finally, fragility estimates are constructed for an example shear wall using the proposed capacity models and conditioning on the shear force and drift demands.

Experimental investigation of multi-layered strong wood-frame shear walls with nonstructural Type X gypsum wallboard layers under cyclic load

A fundamental premise for the design of resilient light frame timber buildings in areas of high seismic activity consists of achieving strong shear walls while keeping nonstructural damage to a minimum, especially by preventing the brittle failure of Type X gypsum wallboard (GWB) finish layers. Under this premise, it has been commonly thought that the stronger the shear wall the lesser the structural contribution of the finishes, and therefore the effect of GWB finishes in strong timber shear walls has been typically ignored by design codes and mechanical models. In the research reported in this paper, the influence of nonstructural finishes on the structural characteristics of a strong light frame shear wall was experimentally and numerically investigated. The wall evaluated in this paper, denoted here Multi-Layered Strong Shear Wall (MLSSW), is representative of walls located at the 1st story of a 7-story building located in Chile, a country where the level of seismic activity is high. The MLSSW has a continuous rod system, double OSB sheathing, robust timber framing, closely spaced nails to attach the OSB sheathing layers to wood-frame members, and is covered at both sides by two layers of screwed Type X GWB. The characteristics of the MLSSW, particularly the quantity and type of nonstructural finishes, are different from those of typical light frame timber walls. Full-scale connection-level tests, both monotonic and cyclic, are reported first, followed by descriptions of the full-scale cyclic assembly-level tests. For comparison purposes, a bare strong wall (i.e., without the GWB layers) was tested as well. The structural response of the MLSSW was evaluated in terms of stiffness, strength, energy dissipation and plastic deformation characteristics. The applicability of the SDPWS analytical model was also evaluated, as well as the applicability of existing numerical models to predict the cyclic behavior of the MLSSW.

Experimental research on standardized bamboo culm components for developing prefabricated bamboo building

Bamboo culm structures are useful for areas with limited access to structural wood, especially for remote bamboo forest areas. This study focuses on developing standardized bamboo culm components for the prefabricated bamboo building, which is potential to replace timber components made of dimension lumber used in modern timber buildings. The basic material properties of Moso bamboo and bamboo culm elements were investigated. Test results show that the main mechanical properties of bamboo culm are comparable to some coniferous wood, such as TC-13A grade (in Chinese standard). Several types of simple and reliable connectors were designed for connecting bamboo culms, attempting to provide standardized bamboo culm elements. The prefabricated shear wall elements were designed with bamboo culms as studs and glubam lumber as perimeter frame for regulate the dimension. Three shear wall models were tested under monotonic and cyclic lateral loading. It was found that the lateral resistance capacity of bamboo culm shear wall is about 64% of that of the similar lightweight wood frame shear walls. Three specimens of bamboo culm trusses were also tested to obtain the design capacity of the roof system. Based on the experimental test results, a prototype single-story building was designed and constructed to assess the feasibility of the constructional details. Carbon dioxide emission analysis revealed the environmentally friendly advantages of this type of bamboo building.

Drift‐ and energy‐based seismic performance assessment of retrofitted wood frame shear wall buildings: Shake table tests

AbstractIn 2004, the Province of British Columbia (BC) announced a multi‐year $1.5 billion seismic retrofit program for the province's 750 at‐risk public schools. The purpose of this program was to quantify the seismic risk of the province's public‐school buildings and to expedite the seismic upgrading of the most at‐risk schools. In order to provide a safe and cost‐effective implementation of this program, the Engineers and Geoscientists BC, in collaboration with the University of British Columbia, has developed a performance‐based probabilistic method and guidelines for the seismic risk assessment and retrofit of low‐rise buildings. As part of this initiative, a number of laboratory experiments have been conducted to provide data that would support the recommendations provided in the guidelines. The laboratory experiments included several full‐scale shake table tests of wood frame systems. The specimens were subjected to sequences of earthquake motions to simulate their performance under main shock‐aftershocks. This paper presents details of seven of the experiment and wood‐frame buildings considered. A detailed discussion of the results of the analyses of the shake table tests data, and performance assessment using drift‐ and energy‐based damage indices is presented. This study highlights the importance of considering the effects of subduction earthquake and mainshock‐aftershock sequences for design and retrofit of wood frame structures.

Lateral Performance for Wood-Frame Shear Walls–A Critical Review

Wood is a green material in line with the sustainable development strategy. From the excellent performance of engineering wood products, modern wood structures represented by light wood structures have gained more development opportunities. As an indispensable part of light wood structure systems, the wood-frame shear wall plays a vital role in the bearing capacity and earthquake resistance of light wood structure systems. This paper is focused on a review of the lateral performance of wood-frame shear walls and classifies the influencing factors in relevant experimental research into three categories, including internal factors such as shear wall structure, external factors such as test scheme, and other factors of material production and test process. Finally, the research prospects in this field were introduced based on the summary of the research status. This work can be a reference for further research on the lateral performance of wood-frame shear walls.

Cyclic Test and Seismic Equivalency Evaluation of High-Capacity Light Wood-Frame Shear Walls for Midrise Buildings

Cyclic Test and Seismic Equivalency Evaluation of High-Capacity Light Wood-Frame Shear Walls for Midrise Buildings

Seismic performance of high-capacity light wood frame shear walls with three rows of nails

With the increase of building height for light wood-frame construction and seismic loads in National Building Code of Canada 2015, stronger shear wall systems have been facing higher demands, especially for mid-rise wood-frame buildings located in high seismic zones. In collaboration with FPInnovations, a new high-capacity shear wall system with two or three rows of nails was developed. This paper presents the test results of shear walls with three rows of nails. A total of 12 specimens (with two standard shear wall specimens as a reference) were tested under reversed cyclic loading. Test results show that shear walls with three rows of nails have approximately-three times the lateral load resistance of a standard shear wall with the same sheathing thickness, nail diameter and nail spacing. The initial stiffness and ultimate displacement of the high-capacity shear wall are also greater than the comparable standard shear wall. Seismic equivalency to standard shear walls in accordance with ASTM D7989 was also conducted. Although shear walls with three rows of nails have three times of lateral load capacities of a standard shear wall, their design values are less than twice the design values of the standard shear walls. This is mainly due to the fact that a higher over-strength factor has to be used to meet the ductility criteria in ASTM D7989.

A simplified approach to assess the technical prefeasibility of multistory wood-frame buildings in high seismic zones

Timber structures present a promising solution to reduce the current environmental footprint of the construction industry. For timber buildings designed in seismic zones, wood-frame shear walls are a common lateral resistant system for low- and mid-rise structures. However, for practitioners and engineers unfamiliar with seismic analysis methods for wood-frame structures, estimation of the systems viability can be complex and time-consuming, hindering an extended adoption of timber structures. Therefore, this paper presents a novel methodology to determine at early design phases the technical feasibility of wood-frame structures in highly seismic zones, so-called Simplified Tool for Technical Pre-feasibility or STTP framework. The methodology was developed by analyzing a comprehensive database of 201 wood-frame buildings designed with different seismic performance factors, architectural configurations, number of stories, soil conditions, and anchorage system. By employing input data readily available at the initial stages of structural projects, the proposed methodology verifies the viability of employing wood-frame shear walls as the lateral resistant system of the structure, and provides additional valuable information such as fundamental periods and wall predesigns. Besides, global stiffness and inter-story deformations can be estimated with an error less than 11%. In this way, accurate feedback can be promptly obtained by employing a minimum amount of resources. The results from the methodology can be employed along with cost calculation methods so as to estimate the economic impact of the project and different solutions.

Influence of the Loading Protocol and Loading Rate on the Characteristics of Timber Nail Joints

Nail joints are one of the key components that control the lateral performance of light wood frame shear walls. In previous experimental studies, researchers have used different loading rates, which failed specimens from less than a minute to more than an hour, to study the characteristics of nail joints. Moreover, there have been different loading protocols used for testing of timber nail joints or shear walls. Although some efforts have been made to address this subject, it is still unclear how the loading protocol and loading rate may influence the performance of nail joints. In this study, a total of 96 nail joints tests were carried out under monotonic and reversed-cyclic loads at three different loading rates, and under three different loading protocols (ISO, CUREE and SPD). The results of the test revealed that the loading rate did not have a noticeable effect on the mechanical properties of nail joints, while the loading protocol did influence those properties. Especially, protocols with larger cumulative damage demands lead to lower ultimate displacement and ductility of nail joints.

Seismic performance factors for timber buildings with woodframe shear walls

Seismic performance factors are an engineering tool to estimate force and displacement demands on structures designed through linear methods of analysis. In Chile, the NCh433 standard provides the regulations, requirements, and factors for seismic design of several structural typologies and systems. However, when it comes to wood frame structures, previous research has found that the NCh433 provisions are highly restrictive and result in over-conservative designs. Therefore, this paper presents an experimental and numerical investigation aimed at proposing new, less restrictive seismic performance factors for wood frame buildings. Following the FEMA P-695 guidelines and a novel ground motion set for subduction zones, this research embraced: (1) testing of several full-scale specimens, (2) developing of detailed and simplified numerical models, and (3) analyzing the seismic performance of a comprehensive set of structural archetypes. 201 buildings were analyzed and results showed that changing the current NCh433 performance factors from R = 5.5 & Δmax = 0.002 to R = 6.5 & Δmax = 0.004 decreases the average collapse ratio of wood frame structures by 13.3% but keeps the collapse probability below 20% for all the archetypes under study. Besides, it improves the cost-effectiveness of the buildings and enhances their competitiveness when compared to other materials, since savings of 40.4% in nailing, 15.9% in OSB panels, and 7.3% in timber studs were found for a 5-story building case study. Further analyses showed that the buildings designed with the new factors reached the “enhanced performance objective” as defined by the ASCE 41–17 standard, guaranteeing neglectable structural and non-structural damage under highly recurring seismic events. Finally, dynamic analyses revealed that the minimum base shear requirement Cmin of the NCh433 standard is somewhat restrictive for soil classes A, B, and C, leading to conservative results compared to archetypes where the Cmin requirement did not control the structural design.

Lateral loading performance of end narrow panel reinforced light wood frame shear walls

PurposeThe sheathing panels of traditional light wood frame shear walls mainly use oriented strand board (OSB) panels, and the damage of the traditional walls is mainly caused by the tear failure at the bottom corner of the OSB panel. In order to improve the lateral performance of the traditional light wood frame shear wall, a new type of end narrow panels reinforced light wood frame shear wall is proposed.Design/methodology/approachThe monotonic loading tests and finite element analysis of nine groups of walls, with different types of end narrow panel, types of fasteners used on the end narrow panels and the end narrow panels edge fastener spacing, are carried out. The effects of different characters on lateral performance of light wood frame shear walls are reported and discussed.FindingsThe failure modes of the wall reinforced by parallel strand bamboo narrow panels with 150 mm edge nails spacing are similar to the traditional wall. Conversely, the failure modes of other groups of walls reinforced by end narrow panels are the tears of the bottom narrow panel or the bottom beam. The end narrow panel reinforced light wood frame shear wall can make full use of the material property of sheathing panels. Compared with the lateral performance of traditional walls, the new-type end narrow panels reinforced walls have better lateral performance.Originality/valueA new type of end narrow panels reinforced light wood frame shear wall is proposed, which can enhance the lateral performance of the traditional light wood frame shear wall. The new-type walls have advantages of convenient operation, manufacture cost saving and important value of engineering application.

Lateral behavior of wood frame shear walls sheathed with densified plywood under monotonic loading

Modern construction projects such as high-rise buildings require increasingly lighter and stronger wood frame shear walls. The stress level of the edge zone in the sheathing panel is generally larger than that of the middle zone under lateral loading, and the mechanical properties of wood-based panels are positively related with density. A series of fast-growing poplar plywood with a marginal or overall densification were prepared in this study for use as wood shear wall sheathing panels. The plywood density was controlled to 550, 550 (edge, 650), 550 (edge, 840), and 650 kg⋅m−3, then full-scaled walls sheathed with the samples were monotonically loaded and compared against a wall sheathed with 12 mm OSB to determine the effects of densification. The elastic lateral stiffness of the densified plywood sheathing wall with marginal density of 650 and 840 kg⋅m−3, relative to 550 kg⋅m−3, increased by 39.8% and 47.8% as the ultimate bearing capacity was increased by 15.5% and 37%, which is better than the commonly-used OSB sheathing wall accompanied by slightly lower ductility. The lateral behavior of the plywood sheathing wall appears to increase as density increases. The marginal-densified plywood can substitute for overall densified material as it presents nearly identical lateral behavior when used as a wood shear wall sheathing panel. The wall with marginal density of 840 kg⋅m−3 showed the best overall lateral performance in this experiment. Relative error was controlled within 10% using the rheological model proposed by Casagrande to theoretically verify the lateral bearing capacity and lateral displacement of the test wall.

Cyclic behavior of wood-frame shear walls with vertical load and bending moment for mid-rise timber buildings

In light wood-frame buildings, the gravitational and lateral force-resisting systems are composed of floor diaphragms and shear walls. During an earthquake, these walls are subjected to the simultaneous action of in-plane vertical force, shear force, and in-plane bending moment. In a mid-rise building, these internal forces can reach large magnitudes, especially on the lower stories, and could have an important influence on the lateral behavior of the walls. The historical use of light wood-frame construction has been in low-rise buildings. Consequently, few investigations have analyzed the effects of high gravitational forces or in-plane bending moment on the lateral behavior of wood shear walls designed for multi-story buildings. This paper presents an investigation of the cyclic lateral behavior of light wood-frame shear walls, designed for mid-rise buildings, subjected to large axial compressive load and in-plane bending moment. Eight wall specimens were experimentally tested with a cyclic lateral displacement protocol, a constant compressive load, and a cyclic in-plane bending moment. The effects of axial compressive load and in-plane bending moment were analyzed. Also, the wall length and the spacing of sheathing nails were varied to study the effects of these variables on the response. A numerical study was performed to show how these effects could influence the response of mid-rise timber buildings. An improvement in the lateral performance of the walls was observed compared to walls tested without compressive force nor bending moment, showing an increase in stiffness, load-carrying capacity, and dissipated energy.

Predicting Behavior of Steel-Clad, Wood-Framed Shear Walls under Cyclic Lateral Loading

HighlightsA finite element analysis (FEA) model was developed to predict behavior of steel-clad, wood-framed (SCWF) shear walls under cyclic loading.This FEA model will be useful in determining post-frame building response to seismic forces.The model will save time and money in developing design coefficients and planning experiments for SCWF shear walls.Abstract. This article presents finite element (FEA) model results of steel-clad, wood-framed (SCWF) shear walls under cyclic lateral loading. The shear wall model consists of beam elements to model framing members, equivalent orthotropic plane stress elements to model corrugated steel cladding, linear spring elements to model nail connectors between framing members, and nonlinear hysteresis spring elements to model screw connectors. Screw connectors attaching steel panels to wood framing and steel panels to steel panels at lap joints were tested under cyclic loading to provide the constitutive relationships needed. A modified Bouc-Wen-Barber-Noori (BWBN) model was developed to capture slack, pinching, and strength and stiffness degradation of screw connectors under cyclic loading. The finite element models were validated by comparing them with experimental test results of six different SCWF shear wall configurations. Predicted peak shear strengths for most load cycles were slightly higher than those from the experimental tests, especially for stitched shear walls. Visual inspection of the FEA predicted hysteretic load curves demonstrated that pinching, and strength and stiffness degradation were well captured. The results of this study demonstrate the utility of the FEA model for comparative studies of different SCWF shear wall constructions under cyclic lateral loading. Keywords: Cyclic lateral loading, Diaphragm design, Post-frame building, Steel-clad wood-frame diaphragm.