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This paper evaluates performance of three representative single-person walking excitation models which can be used to check vibration levels of high-frequency building floors accommodating highly sensitive equipment. The three models calculate vibration responses by harmonic, transient and spectral analyses, respectively.

The evaluation was based on a combined experimental and analytical work comprising modal testing of a prototype floor, repeated measurements of walking-induced vibrations, finite element modelling and model updating to match the measured modal properties. The updated and verified model was then used for the application of the three walking models results of which were then compared with their experimental counterparts.

It was found that all three models were on the "safe" side and overestimated responses measured in all response tests. However, the harmonic model which assumes high-frequency floor resonance caused by the 7th or 8th harmonic of the walking resulted in over-conservative response estimates order of magnitude higher than the maximum measured values in all response tests. Nevertheless, the model which describes walking across a high-frequency floor as pulses representing footfalls consistently overestimated responses by just about 20% and is, therefore, recommended for vibration serviceability checks of this type of floors.

Owing to the slenderness and lightness of most modern footbridges, vibration serviceability assessment becomes a crucial issue in the design process. As one of the key factors, the vibration comfort criterion has an important influence on the assessment of the final result. However, there is an obvious lack of experimental studies in this field, especially regarding the pedestrians' perception of the induced vibrations. In this study, an experiment was conducted to investigate the pedestrians' perception of human-induced vibrations of footbridges. During the experiment, the subjects walked on a pathway that was mounted on top of a shaking table. By imposing sinusoidal excitations with different amplitudes and frequencies, the experiment aimed to determine the influence of the two factors on the walking people's perception. Based on the data collected, perception scales were proposed for both the vertical and lateral vibrations of the footbridge. The established scales comprise five levels that depend on the acceleration amplitude and the frequency. Finally, a comparison between the proposed scales, existing comfort criteria in the literature and international codes was carried out.

The current trend toward longer spans and lighter floor systems, combined with reduced damping and new activities, have resulted in an increasing complaints on floor vibration from building owners and occupants. Heel-drop, jumping, and walking impacts, which may lead to discomfort problems in daily life, were imposed on a large-span arched prestressed concrete truss (APT) girder system studied. The natural frequencies, peak acceleration, average root-mean-square acceleration (ARMS), maximum transient vibration value (MTVV), and perception factor for the girder were obtained and checked against the existing codes and standards. The purpose of this paper is to provide researchers and engineers with a detailed evaluation on the vibration behavior of the APT girder under different human activities, with a comprehensive review on the relevant criteria and some suggestions. Lastly, the following threshold peak accelerations are suggested: 650mm/s² for transient heel-drop impact, 1450mm/s² for transient jumping impact, and 250mm/s² for steady-state walking. In addition, the threshold values of 90mm/s² and 50mm/s² are suggested for MTVV and ARMS, respectively, under steady-state walking.

The serviceability of super-tall buildings depends primarily on the wind-induced structural responses, especially accelerations. To mitigate the discomforting structural vibrations, pendulum-type tuned mass damper (TMD) systems are commonly employed in high-rise buildings. However, for a super-tall building with a considerably low fundamental natural frequency, the suspension length of a pendulum-suspended TMD (PTMD) becomes too long to be feasible as it would occupy substantial building space. For the sake of saving valuable space in a super-tall building, a multistage PTMD system is recommended for vibration control. This paper presents a detailed assessment study on the performance of a multistage PTMD system designed for a 600 m high skyscraper located in a typhoon-prone region in China. Wind tunnel tests are first conducted to determine the wind loads on the building for estimation of structural dynamic responses for the scenarios with and without installation of the multistage PTMD system. Optimal design of the multistage PTMD system is then carried out through examining the mitigation efficiency of the PTMD system for a variety of mass and damping ratios. To restrict the strokes of mass dampers in the PTMD system, two-section damping strategy is proposed. The assessment results demonstrate that the multistage PTMD system with two-section damping can function efficiently to suppress the excessive vibrations of the skyscraper, while occupying a minimal space in vertical and horizontal directions. This paper aims to provide an effective and economic design strategy for vibration control of super-tall buildings under wind excitations.

It is essential to reliably predict the human-induced vibrations in serviceability design of footbridges to ensure the vibration levels to be within the acceptable comfort limits. The human-induced structural responses are dependent on the dynamic properties of structures and human-induced excitations. For concrete footbridges, the elastic modulus of concrete is a vital parameter for determining the dynamic structural properties. To this end, a two-stage machine learning (ML)-based method is first proposed for modeling the elastic modulus of concrete. At the first stage, the ensemble algorithm, i.e. the gradient boosting regression tree (GBRT), is used to predict the compressive strength by selecting eight parameters, including concrete ingredients and curing time, as the inputs. At the second stage, the elastic modulus of concrete is modeled by using the GBRT method with the compressive strength as the input. Pedestrian crowd-induced load is the most common and crucial design load for footbridges. To consider the inter- and intra-subject variability in walking parameters and induced forces among persons in a crowd, a load model is developed by associating a modified social force model with a walking force model. By integrating the two submodels of structure and excitation, an intelligent analysis method for human-induced vibration is finally developed. A concrete footbridge with typical box cross-section subjected to human-induced excitation is analysed to illustrate the application of the proposed method.

Every civil engineering structure, should be designed to fulfill the well-known two requirements namely the strength requirement and the serviceability requirement. In LRFD approach, those two requirements are popularly known as the limit state and the serviceability requirements. The functional failure in this paper, refers to the serviceability aspect. Functional failure of a building, may be originated from one or a combination of 3 factors. They are the soil characteristic, the construction method and the coordination of work activities at the site. This paper describes the tilting of two buildings at two separate locations and at different time. The method of rehabilitation usually dictated by either small or large total settlements the building will experience from which the rehabilitation work could be derived.