木曽町新庁舎コンペ応募案

Project

Architecture in context

Location

長野県木曽町

Year

2017

Type

Competition

### Towards a New Form of Timber Architecture
In considering new possibilities for timber architecture, one approach is to construct a larger whole through the aggregation of numerous small components, reflecting the fundamentally linear character of conventional timber members. From the perspective of maximizing the effective use of locally sourced wood, however, a structural system composed exclusively of linear members may not necessarily be the most rational solution.
The extensive use of sheet-based laminated materials, such as plywood, can reduce waste generated during the sawing and processing of logs and enable a greater proportion of locally sourced timber to be incorporated into the building. For this reason, a prefabricated panel system combining plywood with sawn timber was considered the most materially and economically rational approach.
Timber wall construction is not, in itself, a new structural principle. Nevertheless, by introducing the geometry of the arch, the project seeks to reconcile historical continuity with contemporary expression and to establish the building as a new architectural icon for Kiso Town. Through this synthesis of the archaic and the modern, an otherwise familiar constructional system may acquire renewed architectural significance.
The future development of timber architecture may depend less upon the invention of entirely unprecedented technologies than upon the critical reconstruction of existing ones. Reconfiguring established techniques to produce architecture of both spatial quality and economic rationality is therefore understood as an essential condition for the continued evolution of timber construction.

### Structural Strategy: The Geometry of the Arch
The proposed structural system employs prefabricated timber panels configured as arches. This geometry makes it possible to introduce substantial openings while retaining the strength and rigidity required of the load-bearing walls.
Viewed from the railway side, the repetition of arches visible through the glazed façade establishes both a strong architectural presence and a clear spatial order. The sequence of structural frames gives the elevation a distinctive rhythm and expresses the structural principle directly in the building’s external appearance.
Because timber connections cannot generally be regarded as perfectly rigid joints, the building is conceived as a moment-resisting frame in one principal direction. Along the orthogonal axis, the arched timber panels function as load-bearing shear walls. By assigning distinct structural roles to the two axes, the system is intended to provide a higher level of seismic performance than would be achieved through a frame system alone.
The structural spans are kept as short as practicable, and the conventional Japanese *shaku–ken* modular system is retained wherever possible. This dimensional discipline improves material yield and enables standard construction materials to be used with minimal cutting and waste.
Locally sourced logs may be relatively small in diameter. A log measuring approximately 200 millimetres in diameter, for example, may be difficult to process into even a 120-millimetre-square section. Although this depends on the volume and quality of the available timber, a structural system reliant on large solid-wood members may therefore be poorly suited to the effective use of local forest resources.
Accordingly, the dimensions of the sawn-timber members are minimized wherever possible, while a substantial proportion of the available wood is processed into plywood and incorporated into prefabricated panels. This strategy promotes more efficient material utilization, improves dimensional accuracy through factory production, and reduces the duration of on-site construction.
Where greater structural capacity is required, engineered timber products such as cross-laminated timber (CLT) and laminated veneer lumber (LVL) are employed. Their use reduces dependence on the natural variability of solid timber and contributes to the realization of a timber structure with consistent strength and enhanced seismic resistance.

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