Dynamic problems in footbridges, such as sensible vibrations caused by human induced loading, has on a number of occasions been observed. These vibrations are rarely an ultimate limit state problem, but can be perceived as unpleasant by the pedestrian. In design guidelines there are propositions for how to asses the dynamic problem. However, they only take the walking load into account. It has been shown that, in the case of a running load, accelerations that lie above the comfort zone can occur and that running loads are more severe than walking loads in some cases. It is possible that the running load case has to be considered in future guidelines, and finding a feasible design methodology demands a lot of work. In this thesis, a method aimed to be easily used by a designer is analyzed. The amplitude of acceleration received as a result from a dynamic analysis in a commercial FEM software, was reduced by reduction factors to generate accelerations closer to reality. This could be identified and verified against recommendations.

The influence of the hanger configuration in the arch and deck bending moments under asymmetric loads is widely used nowadays for improved designs of arch bridges. In this work, by means of a parametric study, those hanger configurations that most efficiently increase both the natural frequencies and buckling factors are identified, simultaneously evaluating the dynamic and static performance of timber arch footbridges. A parametric FEM model allows to evaluate the performance of vertical, Nielsen, fan and network hanger configurations together with combinations of them among others for a three-hinge timber arch. The impact of other relevant design choices such as the number of hinges in the arch or the arch slenderness ratio is jointly addressed allowing for design recommendations. The results show a convergence of the natural frequencies regardless of the configuration of the hangers when increasing the number of them. Moreover, the performance of the studied hanger configurations is improved by introducing inclined hangers significantly increasing natural frequencies and buckling factors of the system. This highlights the importance of the stabilizing horizontal reaction appearing at the deck hanger anchor points and thereby improving the bending moment distribution at the arch. Furthermore, the analyses show that the combination of Nielsen and vertical hangers achieves both the largest natural frequency and buckling factor for a reasonable number of hangers. This contrasts with the low sensitivity of the static and dynamic performance that the vertical hanger configuration shows in relation to changes in the number of hangers, arch rise or arch stiffness among others. Additionally, an important consideration when designing three hinge arch bridges is found to be to prevent a local buckling mode from appearing at the crown of the arch. This can also be done by the right choice of the number and configuration of hangers, as has been shown in the thesis. The results produced in this work can be used to guide engineers towards designing arch bridges with higher static capacity and better dynamic performance while reducing at the same time the material consumption. Furthermore, the findings of the work open up the way towards optimization of arch bridge structures.