• Steel and Composite Structures
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• v.45 no.1
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• pp.83-100
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• 2022

Timber is one of the few natural, renewable building materials and glulam is a type of engineering wood product. In the present work, timber-based braces are applied for retrofitting midrise Special Moment Resisting Frame (SMRF) using two types of timber base braces (Timber base glulam, and hybrid Timber-Steel-BRB) as alternatives for retrofitting by traditional steel bracings. The improving effects of adding the bracings to the SMRF on seismic characteristics of the frame are evaluated using load-bearing capacity, energy dissipation, and story drifts of the frame. For evaluating the retrofitting effects on the seismic performance of SMRF, a five-story SMRF is considered unretofitted and retrofitted with steel-hollow structural section (HSS) brace, Glued Laminated Timber (Glulam) brace, and hybrid Timber-Steel BRB. Using OpenSees structural analyzer, the performance are investigated under pushover, cyclic, and incremental loading. Results showed that steel-HSS, timber base Glulam, and hybrid timber-steel BRB braces have more significant roles in energy dissipation, increasing stiffness, changing capacity curves, reducing inter-story drifts, and reducing the weight of the frames, compared by steel bracing. Results showed that Hybrid BRB counteract the negative post-yield stiffness, so their use is more beneficial on buildings where P-Delta effects are more critical. It is found that the repair costs of the buildings with hybrid BRB will be less due to lower residual drifts. As a result, timber steel-BRB has the best energy dissipation and seismic performance due to symmetrical and stable hysteresis curves of buckling restrained braces that can experience the same capacities in tension and compression.

• Structural Engineering and Mechanics
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• v.77 no.3
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• pp.383-394
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• 2021

Column foot in traditional Chinese timber structures may be subjected to be uplifted due to the lateral load and subsequently reset under the vertical loads. The residual moment of the rocking column foot is the most important parameter representing the mechanical behaviors of column foot, and the simplification of joints is the basis of structural analysis of whole structure. The complicated mechanical behaviors of joint and the modeling of the column foot joint has been undertaken historically based on the experiments and numerical simulation. On the condition of limited application range of those models, a lack of simplified model to represent the mechanical behaviors of joint deserves attentions. There is a great need to undertake theoretical studies to derive the residual moment and make better simplified model of the joint. This paper proposes the residual moment and equivalent simplified model of the rotational stiffness for column foot joint. And, the timber frame is established based on the simplified model, which is verified by solid finite element model. Results show that a mutual agreement on the mechanical behaviors of the timber frame is obtained between the simplified model and the solid finite element model. This study can serve as the references of the structural analysis for the traditional timber structures.

• Journal of the Korea Furniture Society
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• v.21 no.6
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• pp.469-478
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• 2010

Fire resistance of new hybrid timber framed wall systems was evaluated in this study. These wall systems are composed of two major structural parts. One part is a heavy timber frame part designed to take charge of whole vertical load using heavy timber post and beam, and the other is an infill wall structure, designed to take charge of whole horizontal load and to provide an established level of fire resistance. A basic concept of this hybrid wall is adopted from a typical furniture structure with frame. A timber post and beam frame is constructed with Japanese Larch solid timber post(180mm by 180mm) and beam(180mm by 240mm). As infill wall systems, two types of walls are applied. One is a typical light timber framed wall with solid blocking and another is a structural insulated panel wall, in which polystyrene insulation is filled between two structural panels to make single structure. For all tested walls, two layers of 12.5mm thick type-X gypsum boards are used on fire exposed side. Prior to tests for hybrid walls, only infill walls are tested without heavy timber frame. All fire resistance tests are carried out in accordance with KS F 2257, and temperatures on several points within wall structure and unexposed wall surface are measured during fire tests. It is considered that the reinforcement of heavy timber frame is significantly efficient for improving the fire resistance of timber framed walls.

• Korean Institute of Interior Design Journal
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• v.14 no.5 s.52
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• pp.10-17
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• 2005

This Study is concerned with the acceptance of Western timber structure and the interior space of church buildings in the early modern period in Korea. Timber roofs have represented a wide variety of constructional forms and have been fundamental to any technological appraisal of the evolution of both of Western and Eastern architecture. Especially the roof structure of the church buildings reflects the technological level, aesthetic sense, and spacial concepts of the age. Between Western timber structure and Korean timber structure, there are many differences in not only structural form but also form of roof, members, load, frame system and etc. And there were various types of framing technique such as timber truss, timber arch, timber vault in the western style church architecture in the early modern period in Korea. I have summarized the character of the acceptance process of Western timber structure and the influences on the interior space of church buildings.

• Structural Engineering and Mechanics
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• v.74 no.4
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• pp.457-470
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• 2020

The force resisting ability of a connection has direct implications on the overall response of a timber framed structure to various actions, thereby governing the integrity and safety of such constructions. The behavior of timber framed structures has been studied by many researchers by testing full-scale-connections in timber frames so as to establish consistent design provisions on the same. However, much emphasis in this approach has been unidirectional, that has focused on a particular connection configuration, with no research output stressing on the refinement of the existing connection details in order to optimize their performance. In this regard, addition of adhesive to dowelled timber connections is an economically effective technique that has a potential to improve their performance. Therefore, a comparative study to evaluate the performance of various full-scale timber frame Nailed connections (Bridled Tenon, Cross Halved, Dovetail Halved and Mortise Tenon) supplemented by adhesive with respect to Nailed-Only counterparts under tensile loading has been investigated in this paper. The load-deformation values measured have been used to calculate stiffness, load capacity and ductility in both the connection forms (with and without adhesion) which in turn have been compared to other configurations along with the observed failure modes. The observed load capacity of the tested models has also been compared to the design strengths predicted by National Design Specifications (NDS-2018) for timber construction. Additionally, the experimental behavior was validated by developing non-linear finite element models in ABAQUS. All the results showed incorporation of adhesive to be an efficient and an economical technique in significantly enhancing the performance of various timber nailed connections under tensile action. Thus, this research is novel in a sense that it not only explores the tensile behavior of different nailed joint configurations common in timber construction but also stresses on improvising the same in a logical manner hence making it distinctive in its approach.

• Journal of the Korean Wood Science and Technology
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• v.51 no.1
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• pp.58-66
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• 2023

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.

• Journal of the Korean Wood Science and Technology
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• v.42 no.2
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• pp.89-100
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• 2014

Energy consumption statistics in 2005 from the Korea Energy Management Corporation show that building energy usage was about 24.2% of total domestic energy consumption, and 64% of total building energy usage was consumed by residential buildings. Thus, about 10% of total domestic energy consumption is due to the heating of residential buildings. Building energy can be calculated by the configuration of the building envelope and the rate of infiltration (the volume of the infiltration of outdoor air and the leakage of indoor air), and by doing so, the annual energy usage for heating and cooling. Therefore, air-tightness is an important factor in building energy conservation. This investigate air infiltration and various factors that decrease it in timber frame buildings and suggest ways to improve air-tightness for several structural types. Timber frame buildings can be classified into light frame, post and beam, and log house. Post and beam includes Han-ok (a Korean traditional building). Six light frame buildings, three post and beam buildings, one Korean traditional Han-ok and a log house were selected as specimens. Blower door tests were performed following ASTM E779-03. The light frame buildings showed the highest air-tightness, followed by post and beam structures, and last, log houses.

• Structural Monitoring and Maintenance
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• v.2 no.3
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• pp.269-282
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• 2015

Civil structures should be designed with the lowest cost and longest lifetime possible and without service failure. The efficient and sustainable use of materials in building design and construction has always been at the forefront for civil engineers and environmentalists. Timber is one of the best contenders for these purposes particularly in terms of aesthetics; fire protection; strength-to-weight ratio; acoustic properties and seismic resistance. In recent years, timber has been used in commercial and taller buildings due to these significant advantages. It should be noted that, since the launch of the modern building standards and codes, a number of different structural systems have been developed to stabilise steel or concrete multistorey buildings, however, structural analysis of high-rise and multi-storey timber frame buildings subjected to lateral loads has not yet been fully understood. Additionally, timber degradation can occur as a result of biological decay of the elements and overloading that can result in structural damage. In such structures, the deficient members and joints require strengthening in order to satisfy new code requirements; determine acceptable level of safety; and avoid brittle failure following earthquake actions. This paper investigates performance assessment and damage assessment of older multi-storey timber buildings. One approach is to retrofit the beams in order to increase the ductility of the frame. Experimental studies indicate that Sprayed Fibre Reinforced Polymer (SFRP) repairing/retrofitting not only updates the integrity of the joint, but also increases its strength; stiffness; and ductility in such a way that the joint remains elastic. Non-linear finite element analysis ('pushover') is carried out to study the behaviour of the structure subjected to simulated gravity and lateral loads. A new global index is re-assessed for damage assessment of the plain and SFRP-retrofitted frames using capacity curves obtained from pushover analysis. This study shows that the proposed method is suitable for structural damage assessment of aged timber buildings. Also SFRP retrofitting can potentially improve the performance and load carrying capacity of the structure.

• Earthquakes and Structures
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• v.23 no.2
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• pp.197-206
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• 2022

Recently, steel-timber hybrid buildings have become prevalent worldwide because several advantages of both steel and timber structures are maintained in the hybrid system. In Taiwan, seismic design specification related to steel-timber hybrid buildings remains void. In this study, the ductility capacity of steel-timber hybrid buildings in Taiwanese seismic design specification is first proposed and evaluated using nonlinear incremental dynamic analysis (IDA). Three non-linear structural models, 12-story, 8-story, and 6-story steel-timer hybrid buildings were constructed using OpenSees. In each model, Douglas-fir was adopted to assemble the upper 4 stories as a timber structure while a conventional steel moment-resisting frame was designated in the lower part of the model. FEMA P-695 methodology was employed to perform IDAs considering 44 earthquakes to assess if the ductility capacity of steel-timber hybrid building is appropriate. The analytical results indicate that the current ductility capacity of steel moment-resisting frames can be directly applied to steel-timber hybrid buildings if the drift ratio of each story under the seismic design force for buildings in Taiwan is less than 0.3%. As a result, engineers are able to design a steel-timber hybrid building straightforwardly by following current design specification. Otherwise, the ductility capacity of steel-timber hybrid buildings must be modified which depends on further studies in the future.

• Earthquakes and Structures
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• v.7 no.1
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• pp.101-117
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• 2014

This paper presents a reliability-based analysis on seismic performance of timber-steel hybrid shear wall systems. Such system is composed of steel moment resisting frame and infill wood frame shear wall. The performance criteria of the hybrid system with respect to different seismic hazard levels were determined through a damage assessment process, and the effectiveness of the infill wood shear walls on improving the seismic performance of the hybrid systems was evaluated. Performance curves were obtained by considering different target non-exceedance probabilities, and design charts were further established as a function of seismic weight. Wall drift responses and shear forces in wood-steel bolted connections were used as performance criteria in establishing the performance curves to illustrate the proposed design procedure. It was found that the presence of the infill wood shear walls significantly reduced the non-performance probabilities of the hybrid wall systems. This study provides performance-based seismic evaluations on the timber-steel hybrid shear walls in support of future applications of such hybrid systems in multi-story buildings.