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This paper describes the state of the art of structural steel reuse in Japan. A significant part of the material is taken from a document titled the Architectural Institute of Japan (AIJ) Recommendations for Sustainable Steel Building Construction (Draft) available only in the Japanese language. The motivations for and potential benefits of steel reuse are examined. The affinity between seismic design requirements and steel reuse is highlighted through a concept known as damage-control design. Some technologies for disassembly are introduced. The historical development and changes in Japanese structural steel are summarized, followed by a discussion on reusability of historical steel reclaimed from existing buildings. Reuse projects whose details are known to the authors are listed. The heart of the paper is a design procedure that specifies the structural engineer's role and involvement in planning, material procurement, and executing a steel reuse project. The discussion is concluded by six directions that should be pursued to make steel reuse a widely accepted reality in Japan. Among those directions are research needs to establish a procedure to quantify the remaining structural performance of reclaimed steel considering possible exposure to earthquakes, establish connections that allow for easy disassembly, and introduce modularized structural systems. High seismicity and the general practice to adopt full moment frames pose unique challenges for steel reuse in Japan.

The authors have continuously studied buckling-restrained braces using steel mortar planks (BRBSM). The performance of energy absorption and fatigue against cyclic loading has been evaluated. Although past studies have clarified the structural performance of BRBSM as single member, it is necessary to study not only the performance of BRBSM as single member but also the performance of BRBSM installed in a building structure. In this paper, a frame model of mid-rise steel structure with BRBSM subjected to earthquake motions with various characteristics is analyzed. Comparing the results of the analysis and the past tests, the seismic behavior of a structure is discussed. Especially, the seismic performance of BRBSM installed in the building structure is evaluated. In addition, the seismic performance of two types of BRBSM; basic and developed high-performance types, is compared and evaluated about cumulative plastic strain energy ratio and cumulative fatigue. As a result, the performance capacities of the both types of BRBSM exceed the required values of BRBSM under severe earthquake motions about cumulative plastic strain energy ratio and cumulative fatigue. The basic-type BRBSM has the fatigue capacity against 2 to 5 times severe earthquake motions. The required values of high-performance-type BRBSM are about a half of accumulated fatigue capacity compared with the basic-type one. The high-performance-type BRBSM is applicable against quite many cyclic loadings of low strain amplitude, and able to be used for long-term service.

The buckling-restrained brace must be able to provide the designed structural performance in actual use. In other words, the buckling-restrained brace must retain its initial quality in during the fabricating process. In this study, for the purpose of ensuring the initial quality of the buckling-restrained brace using steel mortar planks (BRBSM), quality control values at the time of fabrication are set and conduct verification testing on clearance and gap.

The authors previously proposed integrated-facade-systems comprising different types of external louvers integrated with buckling restraint braces. The systems can be applied to both new and existing buildings, paying attention to the building’s appearance, upgraded structural performance and indoor environment. The authors have studied indoor daylight conditions with louver facades and a research paper was published in this journal (Misawa, Hikone, Nakamura, Iwamoto, Iwata, 2014). This research study reports on the energy conservation performance of louver facades and proposes an External Shading Coefficient (ESC) for external louver systems. Situations with five external louver facades and no louvers, facing three facade orientations (East, South and West) are examined. The year-round ESC is simulated every hour using Radiance software for transient solar radiation calculations. Furthermore, by using the proposed ESC, case studies for typical Japanese offices are carried out to verify reduction effects on the annual thermal load and electrical energy consumption of an air source heat pump for each louver set-up. Simulation results are calculated in hourly increments using TRNSYS software; the results show that both thermal loads and electrical energy consumption are reduced regardless of louver types and facade orientations when integrated external louver facades are installed.

In light of global environment issues, the authors proposed a building system comprising steel and timber structure (Hereafter referred to as CSTS), which consist of rolled-H section steel and timber. The CSTS is assumed to adapt for mid-rise story building steel structures. It is a design method of the CSTS that uses the concept of a damage-controlled structure characterized by using buckling-restrained braces as a seismic response control member. It is assumed to use materials such as a cross laminated timber(CLT) for floor structure of the CSTS. The hysteresis model of the CSTS is established based on the available experimental data. Assuming practicality, bending test of the composite steel-timber beam members jointed by bolts is conducted. Behaviour of the composite steel-timber beam members affected by different intervals of bolted joints is evaluated.

In order to address global environmental issues, there is an urgent need for the building structure field to use as much timber as possible to contribute to reforestation, as well as to research and develop a building system that does not diminish the structure’s functionality and safety [1]. The building structure field is required to actively use this wood as timber, but the timber is too weak to use for large buildings. Research and development of an appropriate building system that can utilize such timber is necessary. This study examines the possibility of developing a building system for a composite steel-timber structure utilizing the authors’ wealth of expertise in steel structure construction. Different types of composite steel-timber structure building systems are categorized, and their features are described. Furthermore, the individual types are evaluated for the performance requirements needed to develop a building system.

One approach to promote forest growth is the pruning and thinning of trees. In the field of building structure, it is necessary to use thinned woods as timber positively. However, timber is too weak to apply to the large-scale buildings. Research and development of a building system to use timber are demanded. Authors propose composite steel-timber structure aiming to spread wood to building construction field considering the global environment. First, distribution volumes of planted forest of each age forest class in Japan and its CO2 fixation are shown, investigating forest resources. Finally, the specific example of a composite steel-timber structure is shown and CO2 fixation at building structure model using a composite steel-timber structure is estimated.

In the field of building construction, mass consumption of wood materials contributes to reforestation and becomes the environmental burden reduction. However, an application to conventional timber structures only such as house has a quantitative limit. A newly developed timber structure that is able to make a large-scale building is expected. A composite steel-timber structure will be one of the effective methods to expand the structural variations. In this paper, the bending test of composite steel-timber beam classified typical joint methods is conducted to grasp basic structural performance.

The basic concept of a damage-controlled (DC) structure is that by clearly separating the main frame from the energy absorption members, the main frame is kept within the elastic range and the seis...

The authors conceived a buckling-restrained brace providing stable hysteretic characteristic even under high-strain conditions. Based on the cyclic static loading tests, the performance evaluation formula of the buckling-restrained brace is presented. The buckling-restrained braces in practical uses have welding on the energy absorption area of the core plate. Brittle fracture might be caused at the welding or welding effected zone. In this case, the performance of the buckling-restrained brace would be decreased. In this paper, four kinds of specimens with different welding specifications on the core plates are fabricated. And, cyclic static loading tests are conducted as parameter at temperatures. The performance of the specimens with local welding of well preheating & fishing and without welding is the almost same. The other hand, the performance of the specimens with continuous welding has reduced. Irregularities of weld beads cause brittle fracture in an early stage.

The building facade plays important role for not only appearance designs, but also the safety and the environmental impacts. For satisfying these demands, the authors have proposed the integrated facade system using horizontally arranged louvers. Considering the safety, not only the structural aspect but also fire safety is important. Especially verification of the ejected plume behavior from opening is important to prevent fire spread. The full scale fire experiment, which attached opening with the louver system, was carried out. The ejected plum behavior from this opening was confirmed through temperature around opening and louver, shape of plume, and radiated heat.

The building facade plays an important role not only for ornament designs, but also for the safety and environmental impacts of the building. To satisfy these demands, the authors have proposed an integrated facade system using diagonally arranged louvers. When considering the safety, not only the structural aspect but also the safety aspect is important. Especially the verification of the behavior of the ejected plume from the building's openings is important as to prevent the fire from spreading. A full scale fire experiment, in which the louvers were attached to the opening, has been carried out. The ejected plume behavior from the opening was verified through temperature and radiated heat measurement around the opening and the louvers and through study of the shape of the plume.

The authors are studying a facade system which is integrated architectural, environmental and structural engineering. The system consists of not only structural elements, but also architectural or environmental elements such as claddings. Therefore, some structural system which secures the seismic performance of claddings will be needed. In this paper, a new structural system, called as the trigger system which enables that two seismic performances both of structure and claddings, is proposed, and the efficiency of the system is discussed. The trigger system consists of a trigger mechanism and buckling-restrained brace. First, the outline of the trigger system is described. Next, a seismic performance of a building with the trigger system is analyzed. The trigger system is effective in keeping seismic safety. And, a detail of the trigger system is shown. Finally, an actual size test of the trigger system is conducted to confirm the performance.

A sustainable building steel structure system, which is kind of damage-controlled structure, consists of columns, beams and newly developed connections with buckling-restrained braces like knee brace. The columns and beams are connected with special long steel bars alone, facilitating demolition of the structure and able to be reused the members. Since the connections of beam-to-column are semi-rigid, the columns and beams suffer no damage. The buckling-restrained knee braces only absorb seismic energy. In the past studies, full-scale tests of the connection were carried out. Based on these results, structural models, which modeled the connection were analyzed and a mechanical model for the sustainable building structure system was established. In this paper, a structural design method is proposed on the previous experimental and analytical studies. The detail design method for the newly developed connections with buckling-restrained braces is established. A trial design is conducted where applicability of the design method is shown.