Dundee Tunnel Research

Academic Research - Structural Engineering

Most of Alan Vardy’s recent research has been related to unsteady fluid flows.  Previously, however, he devoted about 15 years to a range of topics in structural engineering.  This has provided a great deal of variety and, in a surprisingly large number of cases, it has fed into subsequent research on fluids-related phenomena.

Structural dynamics

In structural mechanics, as in fluid mechanics, Vardy has focussed more strongly on dynamic behaviour than on static behaviour.  Research topics have ranged in scale from the dynamics of tall buildings to the ultrasonic testing of material inhomogeneity. In the first of these, special attention has been paid to parametric modes of vibration that differ strongly from vibrations at simple modal frequencies.  In the latter, the focus is on the transmission and reflection of high frequency waves.

Masonry structures

One motivation for the research on ultrasonic testing was to assess the quality of masonry walls such as those in brick-built buildings.  This interest arose naturally through simultaneous interests in two seemingly unrelated topics, namely wave mechanics and masonry arch bridges.  Vardy was introduced to the latter by two good friends and colleagues, Bill Harvey and Fraser Smith, who together began the development of the well-known software Archie.  Bill now runs Obvis Ltd.  He is probably the UK’s most talented consultant on the practical assessment of masonry arches.

Arch bridge at Inverernan Coldstream bridge (Built 1763-1766) Bridge pier scour
Arch beauty (Inverernan) Arch elegance (Coldstream) Arch enemy (scour)

Lightweight structures

Masonry arches are inherently compression structures.  They contrast nicely with lightweight structures such as those to which Vardy was introduced by Bill Harvey and Fraser Smith and their architect-colleague Neil Burford.  Bill and Fraser assisted Maunsell Ltd in the design of a 60 m span "plastic" bridge over the River Tay at Aberfeldy. This large, permanent structure was constructed by students of the Civil Engineering Department at the University of Dundee (with professional guidance from Laing O'Rourke). Later, together with Ahmed El-Sheikh, the Lightweight Structures Unit developed a range of structures including a visually stunning demountable canopy for temporary seating at major sporting and other events.

Aberfeldy bridge Grandstand canopy

Opening day - Linksleader bridge, Aberfeldy

Proposed grandstand canopy

Structural adhesives

The late David Smith, formerly chief bridge designer for one of the UK’s largest engineering consultants, initiated a long-running research assessment of a lightweight deck for long-span bridges.  The proposed deck was a novel form of reinforced concrete in the form of a simple open-sandwich.  That is, the concrete was reinforced solely by a steel plate on its tension face.  The composite was formed by applying an adhesive to the steel plate and immediately pouring the concrete. Vardy and others inherited this work from Smith and used it as a test bed for many developments of the idea.  The work involved extensive studies of the structural, thermal and durability properties of adhesives.  It also involved much work on structural topics such as shear displacement and fracture mechanics and it was the original motivation for research on ultrasonic testing.  The open-sandwich form was subjected to extended field tests and was used for a small bridge. It never achieved the standards necessary for use in long span bridges, but it provided a superb basis for training many research students who have subsequently become engineering leaders in their countries.

Selected references

Anandarajah A & Vardy AE (1984) Mode I and II fracture of adhesive joints. J Strain Analysis, 19(3), 173-183

Anandarajah A & Vardy AE (1985) A theoretical investigation of the failure of open sandwich beams due to interfacial shear fracture. Structural Engr, 63B(4), 85-92

Luckyram J & Vardy AE (1990) Shear displacement in bonded structures. J Constr. Steel Research, 16, 71-84

Mackie RI & Vardy AE (1990) Applying the coin-tap test to adhesives in civil engineering. Int J of Adhesion and Adhesives, 10(3), 215-220

Mays GC & Vardy AE (1982) Adhesive-bonded steel/concrete composite construction. Int J Adhesion & Adhesives, 2(2), 103-107

Smith FW, Harvey WJ & Vardy AE (1990) Three-hinge analysis of masonry arches. The Structural Engineer, 68(11), 203-207

Vardy AE & Alsarraj ATA (1991) Coupled axial and flexural vibration of one-dimensional members. J Sound & Vibration, 148(1), 25-39

Wong CK & Vardy AE (1985) Finite prism analysis of plates and shells. Int J Num Meth in Engrg, 21, 529-541

Yokota H & Vardy AE (1991) Anchorage of plates bonded to reinforced concrete beams. Struct Engrg Review,3(3), 157-165