This article studies the dynamic properties of a single span pedestrian timber bridge by in-situ testing and numerical modelling. The in-situ dynamic tests are performed at four different construction stages: (1) on only the timber structure, (2) on the timber structure with the railings, (3) on the timber structure with railings and an asphalt layer during warm conditions and (4) same as stage 3 but during cold conditions. Finite element models for the four construction stages are thereafter implemented and calibrated against the experimental results. The purpose of the study is to better understand how the different parts of the bridge contribute to the overall dynamic properties. The finite element analysis at stage 1 shows that longitudinal springs must be introduced at the supports of the bridge to get accurate results. The experimental results at stage 2 show that the railings contributes to 10% of both the stiffness and mass of the bridge. A shell model of the railings is implemented and calibrated in order to fit with the experimental results. The resonance frequencies decrease with 10–20% at stage 3 compared to stage 2. At stage 3 it is sufficient to introduce the asphalt as an additional mass in the finite element model. For that, a shell layer with surface elements is the best approach. The resonance frequencies increase with 15–30% between warm (stage 3) and cold conditions (stage 4). The stiffness of the asphalt therefore needs to be considered at stage 4. The continuity of the asphalt layer could also increase the overall stiffness of the bridge. The damping ratios increase at all construction stages. They are around 2% at warm conditions and around 2.5% at cold conditions for the finished bridge.

This article investigates the dynamic behaviour of a single span pedestrian timber truss bridge by in situ testing and numerical modelling. The in situ dynamic tests were performed at three different construction stages: (1) on only the truss structure, (2) on the finished bridge without the asphalt layer and (3) on the finished bridge with the asphalt layer. The objective is to better understand how the different parts of the bridge contribute to the overall dynamic properties. The experimental results show that the damping ratios increased significantly for the first lateral mode (from 1.0 to 3.8%) and the first torsional mode (from 1.2 to 3.5%) between stage 2 and stage 3 due to the asphalt layer. The damping ratio is around 1.6% for the first bending mode for the finished bridge. The experimental and numerical results indicate that the stiffness of the asphalt layer is important to consider at stage 3 (10 degrees C) for the first lateral and torsional mode, but not for the first bending mode. Finally, it was concluded that longitudinal springs must be applied at the pot bearings in order to get agreement with the experimental results at all the three stages.

This article investigates the dynamic behaviour of a pedestrian timber truss bridge by in situ testing and numerical modelling. The in situ dynamic tests were performed at three different construction stages: (1) on the finished bridge without the asphalt layer, (2) on the finished bridge with the asphalt layer at warm conditions and (3) same as stage 2 but at cold conditions. The interest of this study is that some modelling details that are usually not considered in the numerical modelling of pedestrian timber bridges are important for this bridge. The stiffness at the connections must be considered in order to obtain accurate numerical results for both lateral and bending modes. The stiffness of the pile foundations has an influence on the first bending mode. In addition, the experimental damping ratio for the first lateral mode is much higher than the values recommended in the design codes.

The dynamic and static behaviour of a pedestrian hybrid steel-timber arch bridge is investigated in this article. The main interest of this study is the modular design of the timber arches consisting of mechanically connected glulam beams. The individual arch segments are interconnected with a novel steel hinge connection. Dynamic and static tests were performed on a full-scale model of an arch segment (3.95 m long) in a laboratory. In situ dynamic tests were performed on the finished bridge. The results showed that the partial composite action of the arches affected the out-of-plane modes of vibration and critical buckling load of the bridge substantially. The stiffness of the steel hinge connections in the arches reduced the critical buckling load of the bridge slightly. The analysis also showed that the slip modulus between the structural elements affected both the dynamic and buckling behaviours. Finally, the experimental damping ratios were around 1-1.5 % for the bridge which is similar to the recommended values in the technical guidelines. 

The dynamic behaviour of a pedestrian timber cable-stayed bridge is analysed by in situ testing and numerical modelling in this article. Two in situ dynamic tests were performed at warm conditions: (1) on the finished bridge and (2) on the stay cables of the finished bridge. The main interests of this study are: a) investigation of the reduced axial stiffness of the stays, b) application of the connection stiffnesses between the timber members and c) evaluation of different modelling alternatives for the deck. The equivalent E-moduli of the stay cables were estimated by calculating the stay cable forces from the experimental resonance frequencies. Applying the reduced values on the E-moduli of the stays provided more accurate numerical results for the first bending mode. The connection stiffnesses between the timber members were shown to mainly affect the lateral modes. The asphalt layer was shown to add some stiffness to the bridge deck even at high temperatures. Modelling the CLT and asphalt layer with a composite layup gave sufficiently accurate results compared to a more detailed modelling alternative for the bridge deck. The experimental damping ratios of the bridge were considerably lower than the values in technical guidelines except for the first lateral mode.