CLT Shear Walls Research Articles

Structural Non-Seismic Design of Post-Tensioned CLT Shear Walls

Structural Non-Seismic Design of Post-Tensioned CLT Shear Walls

Seismic performance assessment of post-tensioned CLT shear wall buildings with buckling-restrained axial fuses

Post-tensioned cross-laminated timber (PT-CLT) walls have been demonstrated to be a low-damage seismic force-resisting system (SFRS) due to their self-centering capability. However, there is still a need to examine the seismic performance of such SFRS in high-seismic risk zones. This study evaluates the seismic performance of 6-, 9-, and 12-storey PT-CLT shear wall buildings in Vancouver, Canada, equipped with buckling-restrained axial fuses. The prototype buildings were designed using the displacement-based design method, and the assessment considered the most recent seismic hazard model provided in the 2020 National Building Code of Canada. To conduct nonlinear response history analysis (NLRHA) and incremental dynamic analysis (IDA), numerical models were developed in OpenSeesPy and calibrated based on component- and system-level experimental tests. The NLRHA and IDA results demonstrate that all the studied buildings have adequate collapse margin ratios, with less than a 10% chance of collapsing at the maximum considered earthquakes.

Seismic performance of RC frame structures with infill CLT shear walls

This paper focuses on the newly proposed RC-CLT hybrid wall systems used in residential buildings. Cyclic loading tests were conducted using 2-storey specimens, to confirm the seismic performance and behavior of the hybrid system and also to investigate the behavior of the RC beams in mid-level and the transmission of shear stress by the CLT wall from upper to lower level. The experimental results showed that CLT could potentially be more superior than RC wall infill in terms of ductility, due to CLT exhibiting higher inter-story drift during shear failure. Furthermore, this study proposes numerical models to simulate the experimental results of the hybrid systems. The RC structural members were modeled using linear elements with MS model inserted at the ends to consider for the N-M interactions. As for the CLT wall, it was modeled using several braced models. The numerical results generally show good agreements with the experimental results. As a result, the numerical model proposed in this study can contribute to better predict the structural behavior of CLT shear wall infilled RC frame with concealed steel plate and drift pin connections.

Experimental Parameter Study on CLT Shear Walls with Self-Tapping Screw Connections

Experimental Parameter Study on CLT Shear Walls with Self-Tapping Screw Connections

Structural Performance of CLT Shear Walls with Hyperelastic Hold Downs

Structural Performance of CLT Shear Walls with Hyperelastic Hold Downs

Structural performance of balloon mass timber shear walls under in-plane lateral loads

Balloon-type mass timber shear walls are one of the most efficient structural systems to resist lateral loads induced by earthquakes or high winds. They are a viable solution for high-rise buildings, since they endure several key advantages, such as reducing connections and avoiding accumulating compression perpendicular to grain in the floors. This system, however, is not included in the 2020 National Building Code of Canada and has no design guidelines in the 2019 Canadian Standard for Engineering Design in Wood, so it is out of reach of most designers. A multi-year research project has been initiated at FPInnovations to quantify the system performance and develop the necessary technical information to codify balloon-type mass timber shear walls. This paper presents results of an analytical study on the structural performance of balloon-type CLT shear walls. A mechanics-based analytical model was updated to predict the CLT panel resistance, in addition to predicting the deflection and resistance of balloon type CLT shear walls. The influence of specific key parameters such as wall length and thickness, aspect ratio, vertical loads, and vertical joints, on the structural performance of this wall system under lateral loads was investigated using the updated model. The results of this study will give a valuable insight into the seismic performance of balloon type CLT shear walls.

Seismic Design of CLT Shear-Wall and Glulam Moment-Resisting Frame Coupled Structure

Seismic Design of CLT Shear-Wall and Glulam Moment-Resisting Frame Coupled Structure

Cyclic Testing of High-Capacity CLT Shear Walls

Cyclic Testing of High-Capacity CLT Shear Walls

Seismic Performance of CLT Shear Wall Infilled Hybrid Steel Frames with Concealed Steel Plates and Drift Pin Connections

Seismic Performance of CLT Shear Wall Infilled Hybrid Steel Frames with Concealed Steel Plates and Drift Pin Connections

Numerical analysis of CLT shear walls using high-fidelity model: Connection to building system

Numerical analysis of CLT shear walls using high-fidelity model: Connection to building system

鋼種・加力履歴をパラメータとしたCLT鋼板挿入ドリフトピン接合部の引張実験

In recent years, the demand for drift pins connection with inserted steel plate has grown due to its high resisting capabilities. The connection is generally used as tensile joints in CLT shear walls for mid-rise building. Moreover, the effect of different steel types of drift pins, usage of bolts instead of drift pins to prevent the opening of slit, drift pin length and its loading history on structural performances are unclear. Therefore, this study reports the results of tensile tests performed on the CLT drift pins joint with inserted steel plate considering the unknown factors mentioned above.

RESEARCH ON STRUCTURAL PERFORMANCE OF SHEAR WALL OF CLT CONSTRUCTION METHOD WITH STEEL BEAMS AND TENSION MEMBERS

This research proposes a structural system for CLT shear wall that demonstrates high CLT shear performance, high deformation capability, and a method for determining its target performance. CLT shear wall with steel beams, using tensile members prevent the brittle failure occurring at the tensile joint, is proposed. To verify the validity of the proposed method, experiments for full scale CLT shear wall specimens are conducted. Test results are simulated by analysis models. By using material property values that are close to the actual conditions in the experiment, the analysis model is able to accurately reproduce the experiment results.

Experimental investigation on the lateral performance of CLT shear walls connected to perpendicular walls

Typically, the mechanical behavior of CLT shear walls for lateral loads is assumed to be governed by the wall base connections, such as hold-downs and angle brackets. However, many experimental and numerical studies available in literature have shown that in “box type” CLT buildings, the connections between perpendicular walls contribute to the lateral response of the CLT shear walls. This study presents the results of an experimental campaign aimed at investigating the lateral performance of CLT shear walls connected to perpendicular walls. Two CLT wall assembly configurations were tested: single Shear Wall configuration (SW), which considers a single CLT shear wall subjected to lateral load, and Shear Wall connected to Perpendicular Wall configuration (SW+PW), which considers a CLT Shear Wall connected to a Perpendicular Wall subjected to lateral load. Results showed that the SW+PW configuration reached higher structural performance in terms of lateral stiffness and lateral capacity than single SW configuration. This increase of lateral performances is governed by the properties of the wall-to-wall connections as well as the properties of the hold downs used in the perpendicular walls. Results of this experimental study show that the perpendicular walls and wall-to-wall connections may be included in the design models of CLT shear walls subjected to lateral loads.

Capacity model of CLT walls with openings and timber plasticization

This paper investigates the effect of timber plasticization on the ultimate lateral capacity of rocking Cross-Laminated Timber shear walls with different characteristics. Simplified capacity models predict a CLT wall ultimate capacity by multiplying the hold-down ultimate resistance by its distance to an assumed pivot point, often coincident with the panel edge. However, timber plasticization at the interface with the foundation can significantly reduce the lever arm of the hold down reaction. This paper aims at assessing the effect of timber plasticization and panel characteristics (geometry, width, presence of openings, etc.) on the position of the pivot point, expressed by the dimensionless lever arm τ, namely the ratio between the distance of the hold-down geometrical axis from the compressed timber resultant and the distance between the hold-down geometrical axis and the panel edge. An extended covariance-based sensitivity analysis of several Finite Element (FE) models, representing all the CLT shear wall design variability was carried out. The FE model, developed in Abaqus, has been calibrated on the experimental cyclic response of a CLT wall panel. Among the chosen parameters, the sensitivity analysis proved that the most significant ones affecting τ are two: the ratio between the hold-down reaction and the maximum resistance of the compressed timber, and the width of the opening. Accordingly, the authors estimated an elementary empirical regression equation based on the FE model results for predicting the dimensionless lever arm (τ) in the capacity equation of CLT panels. The use of this elementary formulation allows the designer to estimate with considerable accuracy the lateral capacity of a CLT panel given the panel geometry, the ultimate resistance of the hold-down, the compression strength of timber perpendicular to the grain and the vertical load. Almost all points used for the linear regression fall within the confidence bounds, thus proving the accuracy of the proposed empirical formula for the dimensionless lever arm.

Experimental and numerical study on the mechanical behaviour of CLT shearwalls with openings

An investigation of the mechanical behaviour of CLT shearwalls, where either door or window openings are cut out of the panel, is undertaken. The main aim of the study is to investigate failure modes related to either mechanical anchor or CLT panel, based on the geometrical dimensions and mechanical properties of shearwall. The results of six full-scale monolithic CLT shearwalls with window or door openings are presented and discussed. The results obtained from the full-scale shearwall tests are used to validate a proposed numerical model, where input parameters, such as the mechanical properties of the CLT panels and mechanical anchors, are obtained from component level tests on beams and connections in isolation. The study shows that differently from single-panel shearwalls with no openings, brittle failure in the CLT panels is a possible mode of failure, which needs to be considered in design. The failure mode in the CLT panels is observed to occur either in bending or net shear in the lintel beams. The proposed numerical procedure is found capable of estimating the maximum load with reasonable accuracy, and the model predictions of the failure mode, number of centre of rotations, and the overall deformation of the CLT panel are accurate for all the studied specimens.

Earthquake-resistant CLT buildings stiffened with vertical steel ties

The interest in multi-storey CLT buildings in seismic areas is leading to the development of new strategies to increase the lateral stiffness of shear walls and to resist high tensile forces due to rocking. Both these purposes can be achieved with vertical steel ties placed at each shear-wall end, to directly transfer tensile forces from each storey to the foundation. Three technologies are proposed for transferring forces from CLT panels to the ties: the use of nailed plates, of screwed connectors, or directly by contact with a thick plate at the top of each storey wall. The dynamic behaviour of CLT shear walls, representing the bracing system of a building and anchored with the aforementioned technologies, has been investigated by means of dynamic analyses and a comparison with the use of common nailed plates or screwed connections without ties. Results, varying the number of storeys and the seismic mass, show that the proposed technology is an effective strategy to increase the feasibility of multi-storey CLT buildings. Complementary non-linear static analyses have been performed to evaluate the actual displacement capacity and ductility of the systems.

Enhanced N-V interaction domains for the design of CLT shear wall based on coupled connections models

The present paper proposes some enhanced models, with different levels of accuracy, for the design of monolithic CLT shear wall based on the definition of reliable N-V interaction domain. The basic assumptions and the novelty aspects of the proposed models are presented. In particular, the adoption of an elastic-perfectly-plastic constitutive law for the timber instead of an elasto-brittle one and the accounting for the coupled axial-shear behavior of the connection elements to derive N-V interaction domains are critically discussed. Moreover, two different methods are adopted for the linearization procedure of the connection load-displacement response. Four of the proposed models are design oriented, two representing a lower bound (more suitable for practitioners), and two representing an upper bound. One more model is developed, which is research oriented and based on hybrid force-displacement approach. The reliability of the different models is investigated by means of numerical analyses exploiting the ultimate failure condition of the materials both in terms of strength and displacement capacity. Finally, the N-V domains for some CLT shear walls are presented and the impact of the different basic assumptions on the results are discussed in comparison with both experimental and numerical literature results.

Structural Performance of RC Framed CLT Shear Walls

Structural Performance of RC Framed CLT Shear Walls

Performance of Coupled Clt Shear Walls with Internal Perforated Steel Plates as Vertical Joints and Hold-Downs

Performance of Coupled Clt Shear Walls with Internal Perforated Steel Plates as Vertical Joints and Hold-Downs

Investigating the kinematic modes of CLT shear-walls with openings

The objective of the current study is to investigate the kinematic modes in CLT shearwalls with openings and the effect of different hold-down configurations on the base shear and the hold-down tensile load. The analysis procedure is validated using tests on five full-scale CLT shearwalls tests. In general, it is found that the lintel slenderness and hold-down stiffness have significant effects on the global kinematic behaviour. For all studied cases, the ratio of the tensile load in the hold-down resulting from single and double hold-down configurations is observed to be between 1.00 and 1.20 for shearwall with door openings and between 1.10 and 1.40 for shearwalls with window openings. Generally, the magnitude of the ratio is decreasing with hold-down stiffness and increasing with the lintel height. The degree of coupling is found to decrease with increased hold-down stiffness and increases with wall segment width. In the zone containing one centre rotation for the entire wall, the degree of coupling increases with the lintel slenderness due to resulting increase in the lintel length, whereas in the zone containing one centre rotation for each wall segment, the results show a decreasing tendency of the degree of coupling with increased lintel beam slenderness. Reasonable agreement between the experimental and modelling results is observed for all walls, with the greatest deviation found for the wall where failure occurred in the lintel beam.