Wood Shear Walls Research Articles

Properties of wood shear walls connected by wood nails

The performance of a wood wall connected by wood nails and twist nails was tested. It was found that during the monotonic load testing, the wood nails connected to the shear panel and stud at the column bottom broke when the deformation reached 12.1 mm. However, the primary failure mode was that the twist nails bent and the head cap became dented in the shear panel. For reciprocating loads, it was found that the wood nails experienced local fracture on the tensile side. The skeleton curve of the wood wall connected by twist nails showed a good trend of bearing capacity changes in both tension and compression sides. Based on the properties of the standard wood wall, a new T-shaped fastener was designed for the midply wood wall. The lateral performance of the reinforced standard wood shear wall and midply wood shear wall were tested. By adding T-shaped pull-up fasteners, sandwich wall structure and double row nails, the strength, stiffness, and ductility of the midply wood wall were substantially better than those of standard walls connected with twist nails using conventional pull-up fasteners.

Performance-Based Design of Posttensioned Cross-Laminated Timber and Light-Frame Wood Shear Wall Hybrid System

Performance-Based Design of Posttensioned Cross-Laminated Timber and Light-Frame Wood Shear Wall Hybrid System

Seismic performance of light wood shear wall infilled timber frame structures with openings

To study the seismic performance of wood frame structures filled with light wood shear walls, three full-size single-layer single span wooden frame structures with infill walls were designed and manufactured. The beams and columns were connected by mortise-tenon joints, and quasi-static tests were conducted on the specimens under reversed cyclic load. The failure modes and load-displacement hysteresis performance of structures with door opening infill wall, window opening infill wall, and solid infill wall were investigated. The seismic performance was analyzed using indicators such as strength, ductility, and equivalent viscous damping ratio. The failure modes of light wood frame filling walls were the tearing of sheathing panel and the failure of nail connections. The filled wall with the opening initially exhibited inclined cracks at the corner of the opening, and then they extended to the periphery. Compared with the solid filled wall, the positive and negative bearing capacity of the structure with door opening decreased, and that of the structure with window opening decreased also. Because the specimens with opening in the filled wall were more conducive to the deformation of the structure when the bearing capacity was not significantly reduced, the ductility of the specimen with door opening was the highest.

Wood and metal shear wall formwork and its performance concerning its uses number and costs

Concrete construction requires a formwork that shapes the structural sections and resists the concrete's weight, representing between 40% and 60% of the overall concrete costs, so the construction team must make cost-effective decisions throughout the project. This research compares the technical and economic performance, unit cost, and the number of metal and wood formwork applications in constructing shear walls in 80 single-family units assembled in 4 real estate units. To reach the yield value of 3,501.18m2, with the metal formwork, 31 uses were required at the cost of 5,873.13 USD; on the other hand, with the wood formwork, 51 uses were necessary at the cost of 14,289.79 USD. After 20 uses, comparing the wood formwork with the metal formwork, the latter was 66% more efficient.

DESIGN AND PERFORMANCE OF NAIL CONNECTION IN WOOD FRAMING SHEAR WALLS

As the preferable lateral resistance system of a wood shear wall is attributedto the good lateral performance of nail connection, this paper aims at investigating the pull-out and shear performances of framing members’ nail connection in wood shear walls under monotonic loading. It was found that the main failure mode of the pull-out behavior of nail connection was the withdrawal of threaded nails from framing members. In addition, the shear behavior of nail connection was characterized by plastic hinge of threaded nails, local tear of spruce-pine-fir(SPF)on the top of nails, and nail caps that were obliquely embedded into the surface of SPF. The average ultimate load and displacement of shear mode were 1.48 times and 5.12 times higher than those of pull-out mode, respectively.According to the research results, thecorresponding exponential numerical model was established, which provided basic data for the lateral performance research and finite element simulation analysis of wood shear walls nail connection.

Lateral loading behavior of the poplar LVL light wood shear wall

Poplar laminated veneer lumber (poplar LVL) is made of fast-growing poplar veneer and structural adhesive, which can well meet the developing requirement of the modern wood structures. This paper mainly focuses on the lateral loading behavior of the poplar LVL shear wall. For this purpose, six shear wall specimens with different opening types were fabricated and tested under the action of monotonic and cyclic loading. Performances were analyzed on the failure pattern, the load-displacement curve, the shear strength, the ultimate displacement, the elastic lateral stiffness, and the energy dissipation. To strengthen the corner joint, an innovative custom-designed hold-down was adopted, and the mechanical performance was also considered. The results showed that the failure of the specimen was mainly due to the yield of the nails and the separation between the stud and the base plate, while the hold-down can greatly improve the shear strength, the ultimate displacement, and the energy dissipation performance of the poplar LVL shear wall without openings. At last, the evaluation formula of the bearing capacity for the light wood shear wall is proposed so as to promote the theoretical basis for the application of poplar LVL in the light wood frame construction.

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.

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.

Structural performance of light wood shear walls built with insulated sheathing panels

Placing an insulation layer between sheathing and lumber framing members reduces thermal bridging in light wood-frame wall construction. However, this soft intermediate insulation layer compromises the lateral resistance and stiffness of the wall due to its relatively low mechanical properties. An experimental study on full-scale shear walls was conducted to investigate the influence of intermediate insulation on the lateral resistance and deflection of light wood-frame walls. Finite element analysis was used for all test specimens and the results were compared to the test data and responses predicted using the mechanics-based design equations provided by the Canadian timber design standard. Results show that an intermediate insulation layer has a significant impact on the lateral resistance and stiffness of light wood-frame walls. Furthermore, it was shown that the lateral strength of such wall assemblages can be predicted with sufficient accuracy based on the strength of its nailed joints using the code simplified design equation, provided that the insulation thickness is not greater than 51 mm. It was also noted that the predicted load-displacement responses using the equation from the Canadian timber design standard are comparable to the predicted responses obtained from the finite element analysis.

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.

Seismic performance of self-centering steel-timber hybrid shear wall structures

This paper presents the seismic performance assessment of self-centering steel-timber hybrid shear wall (SC-STHSW) structures. The hybrid structure introduces extra re-centering action to itself through the combination of the post-tensioned steel frame (PTSF) with the light-framed wood shear wall. Slip friction dampers (SFDs) are used as connectors between the frame and the wood wall. An OpenSees model for the SC-STHSW was established and validated versus experimental results. Then, a 9-story SC-STHSW structure was designed with the direct displacement-based design procedure, and the design was checked through nonlinear time history analysis. Based on the designed 9-story SC-STHSW structure, the influence of a key parameter (i.e., self-centering ratio α E ) on the structure's dynamic performance was investigated by considering different hazard levels. The dynamic response of three 9-story SC-STHSW structures with different α E values was compared in terms of maximum inter-story drift (MaxISD) and maximum residual inter-story drift (MaxRISD). Meanwhile, the fragility curve of a 9-story conventional steel-timber hybrid shear wall (STHSW) structure without self-centering capability was calculated based on the cloud analysis, and the fragility curves were compared with those of the 9-story SC-STHSW. It was found that the increase of α E was not only beneficial to decrease the system's MaxRISD but also positive in enhancing system's control over its MaxISD. The lower limit of α E was suggested to be 0.6 when the system was used in high seismic regions. The 9-story SC-STHSW ( α E = 0.6) was comparable to the 9-story STHSW system in regards to the control of MaxISD, which illustrated the advancement of the new system since, at the same time, it had better re-centering ability to decrease post-earthquake repair costs. • A self-centering steel-timber hybrid shear wall structure was designed through the direct displacement-based design. • The influences of α E on the new structure’s seismic performance were explored. • Based on cloud analysis, the seismic fragility of the new structure was compared with the other structure.

Gaussian Kernel Methods for Seismic Fragility and Risk Assessment of Mid-Rise Buildings

Seismic fragility functions can be evaluated using the cloud analysis method with linear regression which makes three fundamental assumptions about the relation between structural response and seismic intensity: log-linear median relationship, constant standard deviation, and Gaussian distributed errors. While cloud analysis with linear regression is a popular method, the degree to which these individual and compounded assumptions affect the fragility and the risk of mid-rise buildings needs to be systematically studied. This paper conducts such a study considering three building archetypes that make up a bulk of the building stock: RC moment frame, steel moment frame, and wood shear wall. Gaussian kernel methods are employed to capture the data-driven variations in the median structural response and standard deviation and the distributions of residuals with the intensity level. With reference to the Gaussian kernels approach, it is found that while the linear regression assumptions may not affect the fragility functions of lower damage states, this conclusion does not hold for the higher damage states (such as the Complete state). In addition, the effects of linear regression assumptions on the seismic risk are evaluated. For predicting the demand hazard, it is found that the linear regression assumptions can impact the computed risk for larger structural response values. However, for predicting the loss hazard with downtime as the decision variable, linear regression can be considered adequate for all practical purposes.

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.

Deflections Estimation of Light Wood-framed Shear Walls Without Hold-Downs

In the structural design of light wood structures in recent years, people have paid more and more attention to estimating the lateral deformation of buildings. In order to better estimate the lateral deformation of the balsa shear wall without hold-downs, this paper carried out the lateral loading test of the wood shear wall and the monotonic loading test of the nail joint. A formula for lateral load-deformation of nail nodes suitable for engineering entities is proposed. A method for calculating the lateral deformation of wood shear walls without hold-downs is provided. The method is based on the formula for lateral deformation of light-weight timber structure shear walls in China's Code for Design of Timber Structures (GB50005–2017) [1]. This method complements the domestic wood structure regulations very well.

Structural Damage Evaluation of Multistory Timber–Steel Hybrid Structures through Shake Table Tests

Timber-based hybrid structures provide a prospective solution for utilizing environmentally friendly timber material in the construction of midrise or high-rise structures. This study mainly focuses on structural damage evaluation for a type of timber–steel hybrid structure that incorporates prefabricated light wood-frame shear walls into steel moment-resisting frames (SMRFs). The structural damage of such a hybrid structure was evaluated through shake table tests on a 4-story large-scale timber–steel hybrid structure. Four ground motion records (i.e., Wenchuan earthquake, Canterbury earthquake, El-Centro earthquake, and Kobe earthquake) were chosen for the tests, with the consideration of three different probability levels (i.e., minor, moderate, and major earthquakes) for each record. During the shake table tests, the hybrid structure performed quite well with visual damage only to wood shear walls. No visual damage in SMRFs and the frame-to-wall connections was observed. The correlation of visual damage to seismic intensity, modal-based damage index, and interstory drift is discussed. The reported work provides a basis of knowledge for performance-based seismic design (PBSD) for such timber-based hybrid structures.

Quasi-static tests and parametric simulations of hybrid steel frame and light wood shear walls with frictional dampers

A slip-frictional damper connection with a lock-up system between walls and frames in hybrid steel frame and light wood shear wall systems is proposed to protect the main structural components from damage under earthquakes and expedite the post-earthquake recovery process. This paper presents quasi-static tests on six single-story-single-span planar specimens divided into two groups corresponding to 1.65 m and 2.2 m in height, respectively. The lateral behavior for the overall system and the subassemblies, i.e. the frame, the wall, and the damper, corresponding to different damper configurations were compared. Numerical models considering the nonlinear behavior of the sheathing-to-framing connections and the dampers were created with OpenSees to conduct parametric studies to further understand the influence of the wall-to-frame stiffness ratio. The results suggest that the slip-frictional dampers strongly increase the energy dissipation ability and the hysteretic damping, and reduce the damage in the main structural components, especially the shear wall. To maximize these benefits, a total activation load of the dampers around 40% of the capacity of the connected wall is recommended, along with dampers reaching the end of their stroke at a drift corresponding to the yielding of the steel frame. The wall-to-frame stiffness ratio also affects the lateral behavior. Structures with larger stiffness ratios exhibit enhanced energy dissipation capability and larger damage-free inter-story drift. The damped structure remains damage-free up to about 1.5% inter-story drift when the wall-to-frame stiffness ratio is 6:1.

Experimental Dynamic Testing of Full-Scale Light-Frame-CLT Wood Shear Wall System

Abstract This paper will present the results of a shake table experimental test program that focuses on the testing of a one-story full-scale wood shear wall system composed of a post-tensioned roc...

Lateral Performance of Self-Centering Steel–Timber Hybrid Shear Walls with Slip-Friction Dampers: Experimental Investigation and Numerical Simulation

An innovative self-centering steel–timber hybrid shear wall (SC-STHSW) system is proposed in this paper. The SC-STHSW system is composed of two subsystems: the posttensioned (PT) steel frame, and the infill light-frame wood shear wall. Slip-friction dampers are used as connectors between the frame and shear wall. A reversed cyclic loading experiment was conducted to investigate the failure modes, hysteretic characteristics, and the loss of posttensioning force in the system. The working mechanism of the subsystems and the interaction between them were explored. Experimental results revealed that the peculiar flag-shaped hysteretic behavior is available in the SC-STHSW system. Under the coupled effects of the PT technology and the slip-friction dampers, the energy dissipation behavior of the system was transferred from the plasticity in primary structural members to the frictional dissipation in the dampers, and the residual deformation of the system was controlled effectively. A detailed numerical model was developed to predict the hysteretic performance of the SC-STHSW system. The model was validated by comparing the experimental and numerical results. This work supports the application of the innovative steel–timber hybrid structural system in practical engineering.

Self‐centering steel–timber hybrid shear wall with slip friction dampers: Theoretical analysis and experimental investigation

SummaryAn innovative self‐centering steel–timber hybrid shear wall (SC‐STHSW) system is proposed as a promising structural solution for earthquake‐resilient buildings. The SC‐STHSW is composed of posttensioned (PT) steel rocking frame and infill light‐frame wood shear wall. The PT steel frame provides self‐centering capability, whereas the infill wood shear wall improves the lateral stiffness and the load resistance. Meanwhile, friction dampers are assembled into the connections between the steel frame and the infill wall to provide energy dissipation. Theoretical analysis and cyclic loading test were conducted to comprehend the load‐resisting behavior of the proposed SC‐STHSW system, and closed‐form solutions of the moment, shear, and axial force distribution along the length of the steel beam were formulated. Moreover, a nonlinear finite element model was developed, and the model was further used to verify the derived theoretical formulas. Results showed that the SC‐STHSW system was able to undergo large interstory drift without the development of plastic zones in the steel frame members, which resulted in very small residual deformation. The presented experimental and numerical results aim to provide a practical structural solution for high‐performance earthquake‐resilient buildings.

Simplified numerical approach for the lateral load analysis of light-frame wood shear wall structures

Increasing global demand for a sustainable society is driving the development of multi-storey light-frame wood structures, yet their complex structural components make detailed finite element modelling (FEM) impractical. The structural response of these buildings cannot typically be accurately captured with traditional simplified computational methods that rely on the use of parameter-based spring hysteretic properties or mathematical derivation. This paper proposes a powerful simplified nonlinear FEM procedure capable of accurately and efficiently capturing the responses of single-storey and multi-storey light-frame wood shear wall structures with respect to lateral displacement against base shear. The proposed procedure involves the separation of flexural and shear deformations from the total deformation resulting from the detailed model pushover analysis. The nonlinear curves of these deformation components against base shear are used to develop the properties of simplified axial and shear link models based on an approach equating external and internal work. To demonstrate the accuracy of the simplified FEM in conducting pushover analysis for structures with different structural details, 6 single-storey shear walls and 4 four-storey shear walls were modelled using this nonlinear simplified FEM analysis procedure. Compared with detailed FEM procedure, the developed simplified FEM method accurately captured the pushover analysis results with acceptable discrepancies and significantly less computational time. This proposed simplified procedure has the potential for wide applicability in structural design and analysis through the establishment of a simplified model database and the embedment of this database into any commonly used commercial FEM software.