Research Investigators:

Dr Ana Ruiz-Teran, Imperial College London
Dr Peter J. Stafford, Imperial College London
Dr Alfredo Camara, Imperial College London

Research collaborator:

Dr Khan Nguyen, Technical University of Madrid

Current research student:

Caterina Ramos, Imperial College London (funded by the “La Caixa” Foundation research scholarships). PhD student, jointly supervised by Dr Ruiz-Teran and Dr Stafford

Background, context and methodology

Verification of the serviceability limit state of vibrations due to traffic live loads can be neglected in conventional types of concrete road bridges but becomes critical in the design of slender bridges [1], such as in under-deck cable-stayed bridges [2].

In slender road bridges, the conventional deflection-based approach to indirectly assess the serviceability limit state of vibrations is not valid. It can lead to either over- or under-design [1]. The dynamic properties of the vehicles, the size of their wheels, and especially the pavement quality (Fig. 1) are very important when assessing the maximum accelerations registered in a slender bridge due to the crossing of heavy vehicles [2].

Figure 1. Multiple degree of freedom model of a truck in a model with Vehicle-Bridge Interaction.
Figure 1. Multiple degree of freedom model of a truck in a model with Vehicle-Bridge Interaction.

The response obtained using movable loads can be used for a preliminary design. Nevertheless, using movable vehicles, and therefore more sophisticated models accounting for vehicle-structure interaction, is essential when a more accurate response is required for detailed design (Fig. 2) [2].

Fig. 2. Influence of the wheel radius in disc model versus the conventional point contact for a pavement type C. Comparison with a perfect road. Vehicle crossing at v = 60 km/h [2].
Fig. 2. Influence of the wheel radius in disc model versus the conventional point contact for a pavement type C. Comparison with a perfect road. Vehicle crossing at v = 60 km/h [2].

Verification of the serviceability limit state of vibrations due to traffic live load is also essential in footbridges, and in particular in slender footbridges. Our current research is focussed in this area [3].

References

[1] Ruiz-Teran AM, Aparicio AC (2009). Verification criteria of the sls of vibrations for road bridges with slender prestressed concrete decks. In: International FIB Symposium, London (UK); 2009.

[2] Camara A, Nguyen K, Ruiz-Teran AM, Stafford PJ (2014). Serviceability limit state of vibrations in under-deck cable-stayed bridges accounting for vehicle-structure interaction. Engineering Structures, 61, 61-72

[3] Ramos C (2014). Structural behaviour and design criteria of cable-supported footbridges. Doctoral thesis - Late Stage Review (jointly supervised by Dr Ruiz-Teran and Dr Stafford). Imperial College London