Human-induced vertical vibration analysis of landscape pedestrian bridges considering assembled crowd effect

Modern landscape pedestrian bridges, characterized by distinctive landscape features, cause pedestrians to gather in certain places. This changes the loading distribution on the bridge, consequently impacting the vibration response of the structure. Due to the high sensitivity of pedestrians to vibration, it is essential to explore the effects of assembled crowd on vibration comfort of footbridges. The present study adopts the pedestrian load model of ISO 10137 to conduct the acceleration response analysis under both static and dynamic pedestrian loads. The presence of assembled crowd effect significantly influences the bridge vibration response by altering pedestrian pacing frequency. It increases peak acceleration within the pacing frequency range of 1.8 Hz to 2.0 Hz. However, at 2.1 Hz, pedestrian gathering significantly reduces the peak acceleration. Under different pacing frequencies, the effect of assembled crowd on the comfort of bridge traffic is completely opposite. Besides, the impact of pedestrian flow direction is also considered. The “double peaks” phenomenon in the acceleration response due to bidirectional pedestrian flow may cause the root mean square (RMS) acceleration to surpass the comfort thresholds. However, the peak acceleration is considerably lower compared to unidirectional flow, which is advantageous for traffic comfort. This paper may provide insights into understanding the dynamic performance of landscaped footbridges when assembled crowd occurs and support better designs.