Light Timber Frame Research Articles

Proposal of a new typology of structures using timber elements

The paper proposes a new typology of structures using timber elements, divided into homogenous and hybrid, considering the materials from which they were made, along with presenting classification criteria and an example of use. In addition, previously insufficiently specified terms were defined, such as massive timber and light timber frame.

Numerical and experimental investigations of cracked light-frame timber walls

This study investigates the impact of sheathing panel cracks on the structural performance of light-frame, modular-based timber buildings, focusing on the racking stiffness and strength of the individual timber walls in the modules. Previous research has investigated such walls for decades and lead to practical design methods in the harmonized European design code, Eurocode 5. Such hand calculation methods are effective for simple geometries but for walls with openings or complex forms, a correct prediction of stiffness and strength is considerably harder to achieve and load levels where cracks initiate are almost impossible to predict. The paper presents both experimental and numerical studies to investigate how significant cracking in sheathing panels affects the load-carrying capacity of various light-frame timber walls. Finite element simulations using Abaqus are conducted to model the cracking of sheathing panels with the extended finite element method. Moreover, an orthotropic elasto-plastic connector model is introduced for the nail joints. The results indicate that significant cracking of the sheathing panels influences the stiffness and the load-carrying capacity of the wall elements and that the crack initiation and propagation is strongly affected by factors such as the location of openings, the shape of the sheathing panels and the type and position of sheathing-to-framing connections. The numerical results presented align satisfactory with the experimental data particularly regarding load levels at crack initiation and propagation. Furthermore, a parametric study investigates how cracks, orthotropic connector properties and vertical constraint of bottom rails influence the racking strength of different timber walls.

Estimation of wood biomass boiler use in cold climate regions on CO2 emissions of light-frame timber structure

Considering Nagano City, as the cold climate region of Japan, the annual heating load was simulated using a model of a two-story timber structure. The results of simulations were used to compare the CO2 emissions according to the energy consumption of five methods of heating as well as primary and secondary energy sources. Actual data from power and gas companies in Nagano and Japanese energy standards were used for the estimations of CO2 emissions of electric heat pump air conditioners, LNG-powered city gas boilers, LPG boilers, kerosene stoves, and wood biomass boilers using pellets as an energy source. Wood biomass boilers showed CO2 emission savings of up to 85 %, 75 %, 75 %, and 76 %, respectively. The operating and equipment costs were estimated based on secondary energy calculations. The kerosene stove had the lowest cost, but CO2 emissions were lowest in the case of using pellet boilers for 30 years. These results clearly show the potential and merit of pellets used in wood biomass boilers as a renewable energy source when compared to fossil fuels. In addition to the CO2 reduction capabilities, the low operating costs of wood biomass heating systems incentivize their use in cold climates.

Potential for mitigating hurricane wind impact on informally-constructed homes in Puerto Rico under current and future climate scenarios

This study investigates the resilience of informally-constructed light-frame timber houses in Puerto Rico, a region where households with limited resources face significant risks from climate hazards, notably hurricanes. This study conducts a component-based, performance-based wind engineering assessment of informally-constructed house typologies, defined based on extensive fieldwork, under both existing and projected future climate conditions. Key findings highlight the effectiveness of certain mitigation strategies, such as reinforcing roof-to-wall connections, in significantly reducing the probability of failure. Fully-mitigated cases, which involve applying mitigation measures to the roof envelope, roof-to-wall connections, and shear walls, exhibited annual probabilities of failure that are much closer to, but do not necessarily meet, the threshold targeted by American building standards (i.e., ASCE 7). The results also show a dramatic increase in probability of failure of these houses projected by the adopted climate change model scenarios, driven by the increased frequency and intensity of hurricanes in Puerto Rico. Results from feedback from those working in the informal construction sector also identify challenges hindering the effective implementation of mitigation measures in Puerto Rican communities, including a lack of knowledge about how to implement the mitigation strategies and barriers related to real and perceived costs. Taken together these results underscore the urgent need for changes in building practices and revising building standards and suggesting potentially feasible mitigation strategies to improve those practices.

Energy and structural optimization of mid-rise light-frame timber buildings for different climates and seismic zones in Chile

Location determines not only the climatic condition but also the structural loads that the structure must withstand. Given the broad variety of climatic and seismic requirements of Chile, the design of lightweight timber buildings considering both energy and seismic design parameters and boundary conditions becomes a difficult task. The main objective of this research is to analyze and quantify the effect of climates, seismic loads, lateral anchorage, and story number on the optimal energy design solutions, including the seismic behavior in a light-frame timber building. Furthermore, the optimal design was parametrically analyzed considering five Chilean cities that consider different climates, seismic zone, number of stories, and lateral anchorage systems to prevent rocking (overturning) due to lateral seismic forces. The optimal wall insulation thickness, stud spacing, and thermal mass exhibited significant variations depending on the buildings' number of stories, lateral anchorage system, climate, and seismic zone. Therefore, the results of this investigation reinforce the necessity of integrating energy and seismic designs for light-frame timber buildings. The optimal designs obtained in this investigation showed considerable variations depending on the combination of climatic and seismic loads as well as the number of stories and anchoring systems. The article's main contributions are the evidence of the structural and energy design interconnection of light-frame timber buildings and how design variables, such as stud spacing, floor concrete thickness layer, and wall insulation thickness, are related and change according to the different climates, seismic loads, lateral anchorage, and story number.

System effects in T‐shaped timber shear walls: Effects of transverse walls, diaphragms, and axial loading

AbstractThis paper investigates the effects of transverse shear walls (TSWs), out‐of‐plane bending stiffness of diaphragms (FDIA), and axial loading (AXL) on the lateral response of strong wood‐frame shear walls (SWs) used for multistory light frame timber buildings (LFTBs) located in highly active seismic zones. Experimental tests were conducted to understand the requirements for SW‐to‐TSW connections to achieve desirable TSW effects in non‐planar SWs and to characterize the lateral cyclic response of T‐shaped SW assemblies with and without diaphragms and axial load. Both slotted and screwed connections were evaluated as SW‐to‐TSW connections, and both showed sufficient stiffness and strength to achieve TSW effects. However, the slotted connection is preferred because it has a more ductile failure mode. Tests on T‐shaped SW assemblies with and without diaphragms and axial load revealed that TSWs significantly enhance the lateral stiffness and strength but reduce the deformation capacity with respect to that of planar SWs. FDIA and AXL effects further influence the stiffness and strength, overcoming the limitation of smaller deformation capacity in T‐shaped SWs without diaphragms. Diaphragms also make the T‐shaped SW response more symmetrical and improve the evolution of the secant stiffness, the cumulative dissipated energy, and the equivalent viscous damping over increasing levels of lateral drift. Numerical analyses of a theoretical building model with T‐shaped SWs show significant reductions in lateral drift (up to 46%) and uplift (up to 100%) compared to the case with planar SWs only, emphasizing the importance of considering system effects in the seismic design of LFTBs.

Enhanced cross laminated timber (ECLT) for ballistic resistant design

Cross-laminated timber (CLT), an engineered wood product, has grown in popularity in the United States over the last decade due to its ease of assembly, aesthetic appeal, and potential to serve as a sustainable and renewable alternative building material. The improved robustness of CLT over light-frame timber structures has increased its potential in force-protected infrastructure that must resist blast waves and ballistic projectile penetration, but softwood CLT is typically not sufficient to fulfill standard criteria for ballistic threats. To address these threats, enhanced CLT (ECLT) composite panels were manufactured with layers of various reinforcing materials (e.g., steel, FRP) placed between wood laminations. These panels were tested against various ballistic threats during two sets of laboratory tests in order to provide a basis for future research. The first set of testing subjected laboratory-produced Southern Yellow Pine (SYP) ECLT to 84 shots of 0.50-inch (1.27 cm) steel sphere projectiles to evaluate the performance of various reinforcing materials, layups, and fastening methods. A subsequent set of tests subjected commercially produced ECLT of steel-reinforced Spruce-Pine-Fir (South) (SPF-S) to 36 shots of NATO ammunition projectiles traveling at realistic, standard striking velocities. Except for a panel using four layers of a thin and finely woven steel hardware cloth, steel reinforcement was effective in stopping projectiles from all three types of NATO ammunition fired. Ultimately considering the results of these two sets of tests, an initial cost-benefit structure was developed and discussed to compare ECLT configurations holistically, a multi-material wood analytical model framework was established and compared to experimental results, and the first ballistic experimental database for ECLT was created.

Prefab Light Clay-Timber Elements for Net Zero Whole-Life Carbon Buildings

"Net zero whole life carbon" is an ambitious climate target that refers to neutralizing and offsetting the entire LCA-based carbon footprint of a building, including both operational and embodied greenhouse gas emissions. Especially in the Northern climate, viable building envelope structures must, therefore, provide good thermal insulation and low embodied emissions. Carbon offset is typically based on excess on-site renewable energy or purchased carbon offsets disconnected from the building and the site. Viable strategies for carbon neutrality start by minimizing material-related and energy-related CO2e emissions. As a result, new kinds of building envelope structures have been recently introduced in the academic literature and experimental building projects. Traditional construction materials, such as timber and clay, have been sourced locally and processed manually, providing good results for the embodied emissions in life cycle assessment. Recent studies on clay-based construction materials have concluded that more research on clay as a construction material is needed, in particular considering its environmental performance. One specific concern in the Northern climate is that the weather conditions limit clay construction outdoors and prevent industrial-scale application of these solutions. The methods of prefabrication can address these issues. This study introduces the critical technical and environmental properties of a new prefabricated wall element based on a combination of light timber frame and light clay. In a hybrid light clay-timber structure, a mixture of clay and hemp shives is cast between the timber studs. On the one hand, the novelty of this wall structure is the prefabrication that enables industrial applications and upscaling without the limitations of weather conditions. On the other hand, the study assesses the climate impact of a light clay-timber wall element : cradle-to-gate emissions, thermal insulation, and the climate benefits outside the system boundary (carbon handprint) reported in the D-module of the LCA framework. The study also shows that natural materials require a different approach than synthetic materials from industrial processes. There may be variations in the properties of hemp and clay, especially when local sourcing is prioritized for better environmental performance. Moreover, the mixing and installation processes have a significant impact on the final properties and the performance. We show that constructing a light clay wall is a knowledge-intensive process that may result in very different technical properties.

An experimental analysis of full scale light-frame timber modules

Prefabricated timber modules are being increasingly used in the load-bearing structure of entire residential buildings reaching heights up to six stories. The development is driven by the demand of high-quality housing that remains affordable while fulfilling tough environmental requirements imposed on modern construction. To enable further development of this type of buildings additional research is needed despite the considerable number of studies previously performed. This study provides an extensive experimental investigation by subjecting three modules to three different load cases. In each load case, the modules were initially loaded with dead-load placed atop of the module. Thereafter the modules were laterally loaded at the top using a servo hydraulic piston in displacement control. The main aim of the study was to assess the structural behavior of these modules under combined lateral and vertical loading, and also to generate experimental data suitable for verification of finite element models. Results from the test series reveal significant variation in racking stiffness and racking strength depending on the module’s design. Furthermore, in some cases more stiff and stronger mechanical inter-module connections are needed to enhance their global structural performance. Finally, the experimental results reveal that the modules are relatively ductile in their shear response when subjected to horizontal load.

Comparative life cycle assessment of light frame timber and reinforced concrete masonry structural systems for single-family houses in Luxembourg

The building sector's significant greenhouse gas emissions and energy consumption present added challenges to meeting European climate commitments amidst rapid population growth. In Luxembourg, single-family houses dominate the residential buildings, noticeably contributing to construction waste and CO2 emissions. This study compares the environmental impacts of a three-story reinforced concrete masonry single-family house and an identical timber building in Luxembourg, emphasizing greenhouse gas emissions and embodied energy. A cradle-to-grave life cycle assessment was conducted using Building Information Modelling (BIM) models to analyze the global warming potential and primary energy requirements. Environmental product declarations from the producers and the ÖKOBAUDAT German database were used to determine the environmental impacts of the materials. The results show that the timber building outperforms the concrete building with a 43.5% lower global warming potential, while the concrete building demonstrates a 15.6% reduction in primary energy demand. This aligns with the average outcomes of seven similar studies discussed in this paper, at 33.2% and 4.7%, respectively. Moreover, the timber building is 78.6% lighter than the concrete one. When evaluating benefits and loads beyond the system boundary, the timber building provides 3.6 and 4 times greater advantages in terms of global warming potential and primary energy, respectively, compared to the reinforced concrete masonry building. Additionally, the study explores the impact of reusing the floors in the timber building. The cradle-to-grave LCA reveals that reusing the timber slabs improves the building's global warming potential and primary energy by 2.4% and 1.2%, respectively. However, when considering the benefits and loads beyond the system boundary, floor system reuse exhibits a 38.9% surge in global warming advantages while reducing primary energy benefits by 28.1%. The findings advocate for a policy promoting timber construction and reuse in Luxembourg, aiming to achieve the net-zero emission target by 2050.

Numerical and experimental investigations of prefabricated light-frame timber modules

Structures built with prefabricated timber modules have been recognised as an innovative construction method and have been implemented in several countries and regions. In recent years, there have been considerable research activities directed towards these types of structures. However, most of the studies have focused on modules made of steel and concrete in their load-bearing structures and only a few of them are exploring light-frame timber modules. This study focuses on the racking behaviour of light-frame timber modules through experimental and numerical investigations. Full-size tests were performed to examine the global and local structural behaviours of several test modules. A novel finite element model of the modules is also presented. It is a parameterised structural model with high flexibility concerning the generation of different module geometries, materials, fastener types and assembly methods etc. The numerical model was developed in the commercial finite element software ABAQUS, and the numerical results obtained were validated against results from experimental tests. The validation results indicate that the model is capable of achieving satisfactory accuracy in predicting both the global and local structural behaviour of light-frame timber modules. Furthermore, several parametric studies are conducted and discussed to examine how certain parameters affect the structural response of the modules.

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.

Influence of structural irregularity on the q-behaviour factor of light-frame timber buildings by means of incremental dynamic analysis

This paper investigates the role of sheathing-to-framing connection ductility in the evaluation of the structural q-behaviour factor for Light-Frame Timber (LFT) buildings, by means of Incremental Dynamic Analyses (IDA). This approach allows to consider nonlinear cyclic behaviour of the walls, which cannot be taken into account with the static approaches used in most of the available literature on LFT buildings. To this aim, Finite Element wall models, preliminary calibrated towards a cyclic full-scale experimental test, are built to study six case-study buildings, both regular and non-regular, with 2, 3 or 4 storeys, which were designed according to Eurocode and Capacity Design provisions. Parametric analyses are performed by varying the displacement-ductility of the panel. Finally, numerical results are discussed in terms of q-behaviour factor, and its sensitivity to structural irregularities, with respect to existing code provisions for timber buildings.

Experimental Study of the Charring of I-Joists and Recession of Combustible Insulation in Light Timber Frame Assemblies with Comparison to Eurocode 5

Design models are commonly used in fire safety design of light timber frame assemblies. Parameters for use in the models are available for rectangular members with mineral wool, wood fibre or cellulose insulation and for assemblies with I-joists and mineral wool. For assemblies where I-joists and combustible insulations are combined, design parameters are missing. Five fire experiments with two I-joist types and four combustible insulation products have been conducted. The aim was to study charring of I-joist flanges and recession rates of combustible insulations and in addition, to compare their behaviour to the new and existing models of Eurocode 5. Charring rates for the flanges were 0.40–0.76 mm/min and 0.54–1.72 mm/min for the protected and post-protected phase, respectively. Rates decreased with increasing flange size. Charring rates for flanges of solid wood and LVL were comparable. The results show that lateral charring of I-joist flanges can be significant in the protected phase. The tested insulation products showed a lower recession rate than values reported for glass wool insulation, with a more pronounced difference for wood fibre and cellulose insulations. The low recession rates compared to previously reported generic values can possibly be explained by better product-specific properties, negligible shrinking and slightly different test set-up. The insulation stayed well in place after gypsum board fall-off and best-practice for keeping the insulation in place is given. The results, completed with future loaded full-scale tests, can give basis for further development of design models for assemblies with I-joists and combustible insulations.

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.

Light timber framed wall under fire: Effect of the load and cladding

Light Timber Frame Walls are made of solid timber elements and are usually protected by cladding materials (gypsum). This investigation finds the effect of different load levels and cladding systems on the fire resistance. The timber frame structure is made with three studs and two rails, and will be analysed with two different protection levels. The computational model includes the thermal analysis under standard fire and a sequential mechanical analysis with time increments. Both, thermal and thermo-mechanical models are validated against experimental results developed in the reduced scale and full scale. The timber frame structure is deemed to have failed when it is no longer supporting the test load. The results are also compared with the failure criteria used for the experimental tests. The timber frame is deformed and all simulated models attained the global bucking instability mode, with studs moving to the outside of the furnace, due to the effect of load and charred layer. The fire resistance of a double-layered light timber frame wall is higher than a single-layered, and both decrease with the load level. This ability is reduced by 46%, on average for all load levels, when using only one gypsum layer. A new formula is proposed to determine the fire resistance, based on the load level and cladding systems. The fire resistance of the specimens with two layers of gypsum plates decreases faster than the specimens with one layer of gypsum, with respect to the increase of the load level.

Lateral Resistance of Reinforced Light-Frame Wood Shear Walls

In light-frame timber construction, the shear wall is one of the most important components that provide resistance to lateral loads such as earthquakes or winds. According to KDS (Korea Design Standard) 42 50 10, shear walls are to be constructed using wood-based structural sheathing, with studs connected by 8d nails spaced 150 mm along the edge and 300 mm in the field. Even though small-scale residential timber building can be designed to exhibit seismic resistance using light-frame timber shear walls in accordance with KDS 42 50 10, only the abovementioned standard type of timber shear wall is available. Therefore, more types of timber shear walls composed of various materials should be tested to measure their seismic resistance, and the results should be incorporated into the future revision of KDS 42 50 10. In this study, the seismic resistance of shear walls composed of structural timber studs and wood-based structural sheathing with reinforced nailing is tested to evaluate the effects of the reinforcement. For the nailing reinforcement, shear wall specimens are constructed by applying nail spacings of 75–150 mm and 50–100 mm. For the shear wall specimens with one sheathing and reinforced nailing, the shear strengths are 1.7–2.0 times higher than that of the standard shear wall (nail spacing of 150–300 mm). The shear strength of the shear walls with sheathing on both sides is 2.0–2.7 times higher than that of the standard shear wall.

From Dysfunction to Functionalism: The Evolution of Military Construction in the Interwar Period Poland

The purpose of the article is the general characteristics of military residential architecture built in the 1920s and 1930s in the 2nd Polish Republic. In the newly restored Poland the most pressing problem was the improvement of the housing conditions of the population. The military, who contributed the most to the reinstating of independence held special privilege with the state officials. Therefore, the problem of their quartering was resolved with utmost preference. After an unsuccessful period of trial and error with traditional and light timber frame construction the government addressed this problem systemically establishing the Military Accommodations Fund with a dedicated budget for creating typified, repeatable solutions. The MAF commissioned specific designers, held open as well as limited competitions and hired a cadre of architects and engineers to come up with designs that could rapidly and cost effectively replenish the housing base with functional, hygienic solutions. Because the MAF was well funded, the most prominent polish modernist architects readily cooperated with the organization making Polish interwar <i>architectura militaris</i> an engine of modernization.

Structural health monitoring of South America's first 6-Story experimental light-frame timber-building by using a low-cost RaspberryShake seismic instrumentation

A low-cost seismic instrumentation system (LCSIS) has been implemented and validated for the structural health monitoring of South America's first experimental 6-story light-frame timber building (Peñuelas Tower). Furthermore, coupling the LCSIS with relative humidity and temperature measuring system has allowed for investigating the ambient-induced variations of the building's dynamic properties. The LCSIS has been accomplished using six accelerographs RaspberryShake® R4SD (R4SD), which were interconnected using a local network controlled by an auxiliary Raspberry Pi3 (RPi3). The RPi3 performs the following activities: (i) it works like an NTP server that allows the synchronization between the seismic instruments; (ii) it is connected to the internet to provide remote control and communication; (iii) it has internal subroutines to periodically estimate the dynamic properties of the building by using the FDD method from hourly ambient vibration tests based on the velocity data obtained from the vertical geophones included in R4SD instruments. The LCSIS was electrically supplied using a 55A battery and a battery charger to ensure operability during power outages. The building's natural frequencies and mode shapes were identified from operational modal analyses of five integrated ambient vibration tests, measured by a conventional seismic instrumentation system (Episensors ES-U2), showing consistent dynamic properties. The LCSIS was validated from shake table tests, observing a good agreement for signal frequencies smaller than 25–30 Hz in comparison with conventional measuring systems as well as measuring the response during an earthquake of low-intensity Mw = 4.6. Once the LCSIS was validated, a BME280 sensor was added to continuously monitor the temperature and relative humidity inside the building, which allowed for the implementation of a structural health monitoring system to track the ambient-induced variations of three principal natural frequencies. It was found a high sensitivity of the building's natural frequencies due to ambient variations, exhibiting peak-to-peak daily variations of 9.5–10.9 % and overall variations of 24.7–29.2 % during an eleven-month period, thus evidencing that timber structures could be more susceptible to temperature and relative humidity variations than other structural systems. Unexpectedly, the timber structure was found to be stiffer under moist conditions, which may be attributed to the tightening of timber assemblies due to wood swelling. A 48-hour state-space model was built to accurately compute the estimated natural frequencies as a function of the recorded temperature and relative humidity, showing that this procedure could be used to effectively disaggregate the ambient-induced variations from changes generated by damage or other unknown sources.

Nonlinear FE-analysis and testing of light-frame timber shear walls subjected to cyclic loading

Light-frame timber shear walls have been used as load-bearing elements in buildings for several decades. To predict the performance of such structural elements under loading, numerous analytical and numerical models have been developed. However, little focus has been on the prediction of the plastic damage behaviour and unloading of the walls. In this paper, a parametric Finite Element (FE) model is further developed by introducing elasto-plastic connectors to simulate the mechanical behaviour of the sheathing-to-framing connections. To verify the accuracy of the elasto-plastic model, full-size walls were tested and compared with results from simulations. The numerical results, from a few loading cycles, indicate that the model achieves reasonable accuracy in predicting both the nonlinear elastic and plastic deformations. Both experimental and simulation results demonstrate the importance of opening locations relating to the external racking force. The results also indicate that for a double-layer wall, its racking strength can be achieved by summation of the separate contribution from each layer. Furthermore, the internal layer was observed to contribute significantly less than the external layer since its nail pattern was based on the sheathing pattern of the external layer.