Steel-deck composite floor systems are being increasingly used in high-rise building construction, especially in Australia, as they are economical and easy to construct. These composite floor systems use high strength materials to achieve longer spans and are thus slender. As a result, they are vulnerable to vibration induced under service loads. These floors are normally designed using static methods which will not reveal the true behaviour and miss the dynamic amplifications resulting in inappropriate designs, which ultimately cause vibration and discomfort to occupants. At present there is no adequate design guidance to address the vibration in these composite floors, due to a lack of research information, resulting in wasteful post event retrofits. To address this gap in knowledge, a comprehensive research project is presented in this thesis, which investigated the dynamic performance of composite floors under various human induced loads. A popular type of composite floor system was selected for this investigation and subjected to load models representing different human activities. These load models have variable parameters such as load intensity, activity type (contact ratio), activity frequency and damping and are applied as pattern loads to capture the maximum responses in terms of deflections and accelerations. Computer models calibrated against experimental results are used in the analysis to generate the required information. The dynamic responses of deflections and accelerations are compared with the serviceability deflection limits and human comfort levels (of accelerations) to assess these floor types. This thesis also treats the use of visco-elastic (VE) dampers to mitigate excessive vibrations in steel-deck composite floors. VE damper properties have been presented and their performances in reducing the excessive vibrations have been assessed this thesis. The results identified possible occupancies under different loading conditions that can be used in planning, design and evaluation. The findings can also be used to plan retrofitting measures in problematic floor systems.

The dynamic behaviour of lightweight footbridges is often susceptible to HumanInduced Loads (HILs). Generally HILs are taken into account as moving harmonicfunctions in which the loading frequency represents the step frequency of the pedestrians.In this way, there may be resonance if the loading frequencies fall within therange of the natural frequencies of the bridge, potentially compromising the serviceabilitylimit state of the structure. Therefore, it is important to understand how toaddress and model HILs in the context of lightweight and slender structures. Furthermore,interesting effects can be considered in the field of footbridge dynamics,such as the Human Structure Interaction (HSI) effect. The HSI effect can be understoodwithin a framework in which pedestrians behave as Tuned Mass Dampers(TMDs), possibly modifying the dynamic behaviour of the footbridge. In addition,the evaluation of the dynamic response of a footbridge is usually made through atime consuming dynamic analysis using the Finite Element Method (FEM). Mostof the analysis of this type of slender structures rely on a prescribed stationary harmonicloading scenario, and this is usually done in the context of a walking crowdevent and not much attention is given to running load events.The aims of this research project are to study the influence of running and walkingloads on the dynamic response of footbridges as well as to investigate and developa closed-form method in order to simulate the dynamic behaviour of footbridgessubjected to HILs. This has been achieved by comparing different approachesin order to simulate running load events for a small number of pedestrians withrespect to experimental results (Paper I). In addition, the simply supported beamand the clamped-clamped beam (Paper II) are studied when subjected to a movingharmonic load in a closed-form framework. Then, a comparison between normalwalking and normal running conditions is made. Finally, a general closed-formsolution for the moving harmonic load problem (Paper III) is developed using the2D Bernoulli–Euler beam theory for a continuous beam system on elastic supports.The results from the study indicate that running is more critical than walking fora single pedestrian crossing, despite the fact that it is easier to achieve a steadystate condition in a normal walking event than in a normal running event. Finally,the general solution of the moving harmonic load problem is found and it can beused to solve any load spectra in the time domain, with its static component, for ageneral multi-span beam system. / Slanka och lätta gångbroar är ofta känsliga för dynamisk belastning från fotgängare.Dessa laster betraktas ofta som harmoniska funktioner där lastfrekvensenberor på stegfrekvensen. Resonans kan uppstå om stegfrekvensen sammanfallermed någon av brons egenfrekvenser vilket potentiellt kan överskrida föreskrivnavibrationsnivåer. Kännedom om dynamisk fotgängarlast är därför viktig, framföralltför dynamiskt känsliga konstruktioner. Samverkan mellan fotgängare ochbro kan också ge upphov till intressanta samband. Fotgängarna kan i detta sammanhangliknas med en massdämpare som kan ändra brons dynamiska egenskaper.Dynamiska analyser av gångbroar utförs ofta med FEM-analyser som kan varatidskrävande. Vanligen baseras analyserna på föreskrivna stationära harmoniskalaster, ofta baserat på gånglaster och sällan med beaktande av löparlaster.Syftet med denna uppsats är att undersöka inverkan av löpar- och gånglasters inverkanpå gångbroars dynamiska respons samt att utveckla en analytisk metod föratt simulera dessa laster och dess respons på broar. Detta har utförts genom attjämföra olika sätt att simulera löparlaster och jämföra broresponsen med experimentelldata (artikel 1). En analytisk lösning för rörliga harmoniska laster redovisasför fallet fritt upplagd och fast inspänd balk (artikel 2), med vilken inverkan av gångochlöparlaster jämförs. En mer generell analytisk lösning för rörliga harmoniskalaster (artikel 3) baseras på Bernoulli-Euler balkteori för kontinuerliga balkar påeftergivliga upplag.Resultaten från föreliggande arbete visar att för en enskild fotgängare är fallet medlöparlast mer kritiskt än gånglast, trots att det är lättare att uppnå ett fortvarighetstillståndför gånglaster jämfört med löparlaster. Den generella lösningen för rörligaharmoniska laster som redovisas kan användas för att lösa godtyckliga lastspektrai tidsdomän, inklusive dess statiska komponent, för generella balkar. / <p>QC 20210302</p>