Second Severn Bridge

The Second Severn Crossing is a cable stayed bridge with a main span of 456m and back span of 245m total length, each with two piers. The deck is a composite structure with a concrete slab and comprises two external concrete edge beams and two longitudinal steel girders. These girders are linked by regularly spaced steel cross beams. Two slightly inclined planes of cables attached to the "H" shaped concrete pylons support the deck near its outer edge. Each pylon rises to a height of approximately 100m above deck level.

The wind engineering studies undertaken included the following:

Sectional Model Tests for Bridge Deck

To assess the aerodynamic stability of the bridge against flutter and vortex-induced oscillation, and to provide the static force coefficients for the calculation of wind loading.

During the course of the sectional model study, the deck design evolved through many changes. These changes were prompted by early findings of the wind tunnel tests as well as other design considerations unrelated to the aerodynamic investigations.

Theoretical Analysis of Buffeting Response

To determine the wind buffeting response and to establish the design wind loads for the completed bridge.

Aeroelastic Study

The objectives of the full aeroelastic model study were; to check the aerodynamic stability, including flutter and vortex shedding, and to measure forces, bending moments and deflections due to wind loads, employing a 1:125 scale model of the bridge in it’s completed stage and at different stages of construction.