Design of structural timber connections

Design of structural timber connections

Date Published

21 August 2022

Document Type

Category

Author

TRADA
Summary

Connections are an essential part of any structure, and in timber structures they are often the most critical part of a design. The timber section size is often determined by the strength of the section remaining after drilling holes for bolts or dowels, or by the spacing requirements for the fasteners, rather than the load-carrying capacity of the timber. Therefore the design of connections is an important section of any timber design standard.

When selecting and detailing connections for a particular application, designers must consider four criteria:

Load transfer
Fire resistance
Durability
Appearance

This Wood Information Sheet (WIS) focuses on the load transfer aspect and is intended mainly for Design > Engineer;s and architects. This WIS is an overview of the subject with signposts to more detailed sources that are listed at the end.

Key Information

From a materials point of view, there are three basic connection types: all-timber connections, connections with metal fasteners and connections with adhesives.

The dowel types fasteners are nails, staples, wood screws, coach screws, bolts and steel dowels.

When considering means of load transfer, there are two basic connection types: laterally loaded, where the load is parallel to the plane of the joint, and axially loaded, where the load is perpendicular to the plane of the joint.

Case studies

Norfolk County Council chose the Sheppard Robson/Ramboll design for its first Academy through a competitive bid process via the Academies Framework.

Simpson & Brown Architects has designed a new visitor centre for English Heritage, using timber to create its principal space, a light-filled arcaded hall of tall glulam arches, reflecting the characteristic columns and pointed arches of the Gothic ruins.