Now showing 1 - 7 of 7
  • Publication
    Testing and long-term monitoring of a curved concrete box girder bridge
    apital investment in national infrastructure is significant. The need to maintain and protect critical infrastructure links has led in recent years to significant developments in the area of structural health monitoring. The objective is to track a structure’s long-term performance, typically using sensors, and to successively compare the most recently measured responses with prior response history. During construction of the West Street On-Ramp, a curved concrete box girder bridge, located in the city of Anaheim (California), eleven accelerometers were permanently installed on its bridge deck. The associated data acquisition system was configured to record once a specified threshold acceleration response was exceeded; during the period 2002–2010 a total of 1350 datasets including six earthquakes, for each of the eleven sensors, were acquired. This automatically acquired data was supplemented, during the summer of 2009, with responses measured during controlled vehicle tests. Six accelerometers were additionally installed on the frame of the weighed test vehicle. This paper presents the findings of the analyses of these measured data sets and serves to inform owners and managers as to the potential feedback from their instrumentation investment. All response histories were analyzed using frequency domain techniques for system identification. Extraction of the modal characteristics revealed a continuous reduction, of approximately 5%, in the first three natural frequencies over the period of the study. The measured responses from the vehicle sensors are discussed in the context of identifying the potential for bridge frequency measurement using instrumented vehicles.
    Scopus© Citations 71  525
  • Publication
    Nonstructural Partitions and Floor Vibration Serviceability
    (American Society of Civil Engineers, 2015-03) ; ;
    Nonstructural vertical partitions and cladding can have a significant effect on the vibration serviceability of floor systems. A typical modern office building, consisting of steel–concrete composite floor systems, was created to investigate the potential beneficial effects of integrating nonstructural partitions into structural floor systems to reduce floor vibrations due to walking excitation. Two models of this building are presented: one to represent the completed building with an open-plan layout and another with partitions added in a beneficial pattern to enhance the floor’s vibration performance. The addition of nonstructural partitions successfully reduced floor accelerations due to walking excitation and helped the floor to satisfy the vibration serviceability criterion for office floors. The potential of vertical full-height nonstructural partitions and cladding to transmit vibrations between floors was also investigated. A vibration transmission simulation was conducted on the finite-element (FE) model to quantify vibration transmission between floors through the structural frame and nonstructural vertical partitions and cladding. The results were then compared with experimental results previously recorded on the floors of a real-life Charles Institute Building in Dublin, Ireland, featuring the same type of partitions but with a different structural frame. It was concluded that both the FE model and the real-life building featuring structural elements and full-height partitions have the potential to transmit a significant level of vibrations between two adjacent floors. The results presented in this paper will be of interest to design engineers and researchers in the area of vibration serviceability of floor systems because it highlights the potential of nonstructural elements to reduce the floor vibration response to acceptable levels, as well as their ability to transmit vibrations between floors.
    Scopus© Citations 13  555
  • Publication
    Investigation of the Rail-Induced Vibrations on a Masonry Historical Building
    Increasingly historic masonry buildings are subjected to higher levels of traffic and rail vibrations due to urbanization and population growth. Deterioration and destabilisation of these buildings may result, especially if they were previously damaged (e.g. earthquakes or settlement problems). To better understand building response, vibration measurements were conducted on the Little Hagia Sophia Mosque, located adjacent to Istanbul’s Sirkeci-Halkali railway line. Transport-induced vibrations were recorded at several points on the ground and building. Attenuation characteristics in the ground and amplification features on the building were examined. Peak particle velocities often exceeded previously established thresholds for human perception and in some cases for structural damage. These are evaluated with respect to the building’s condition.
      812Scopus© Citations 7
  • Publication
    Mechanical behaviour and 3D stress analysis of multi-layered wooden beams made with welded-through wood dowels
    This paper presents experimental and numerical investigations on multi-layered timber beams using welded-through wood dowels in place of traditional poly(vinyl acetate) (PVAc)-adhesives (or metallic nails). Four-layer beams were constructed with varying numbers of dowels, in each, and then loaded using four-points bending tests to evaluate the mechanical performance of these beams. The practical difficulties encountered in constructing deeper multi-layer beams are discussed and possible solutions which have been employed for the purpose of this work, and proved successful are presented. In order to investigate thoroughly the full potential of multi-layered beams with a very limited number of experimental studies, a 3D FE model has been presented, validated against experimental results and then used to study some influential parameters. The results showed that a reasonable bending stiffness of multi-layered beams is achievable with a good combination of material and geometric parameters.
    Scopus© Citations 72  1296
  • Publication
    Experimental study of timber-to-timber composite beam using welded-through wood dowels
    This paper presents exploratory research related to novel full-scale multi-layered timber beams with composite action achieved with welded-through wood dowels. Different multi-layer beam designs, where the timber layers were interconnected with welded wood dowels providing interlayer shear resistance, were tested in bending with different dowel densities. The main originality of this study is the achievement of dowel welds through greater depths of sections than has previously proved possible. The practical difficulties encountered in constructing deeper multi-layer beams, and the successful solutions arrived at, are discussed. The significance of the research reported is the demonstrated ability to produce multilayered timber sections which are structurally efficient and do not require non timber based joining agents such as nails or adhesive.
      1329Scopus© Citations 46
  • Publication
    Enhancement factors for the vertical response of footbridges subjected to stochastic crowd loading
    The vertical acceleration response of a hypothetical footbridge is predicted for a sample of single pedestrians and a crowd of pedestrians using a probabilistic approach. This approach uses statistical distributions to account for the fact that pedestrian parameters are not identical for all pedestrians. Enhancement factors are proposed for predicting the response due to a crowd based on the predicted accelerations of a single pedestrian. The significant contribution of this work is the generation of response curves identifying enhancement factors for a range of crowd densities and synchronization levels.
    Scopus© Citations 58  775
  • Publication
    The Evolving Dynamic Response of a Four Storey Reinforced Concrete Structure During Construction
    Structures include elements designated as load bearing and non-load bearing. While non-load bearing elements, such as facades and internal partitions, are acknowledged to add mass to the system, the structural stiffness and strength is generally attributed to load bearing elements only. This paper investigates the contribution of non-load bearing elements to the dynamic response of a new structure, the Charles Institute, in the grounds of University College Dublin (UCD) Ireland. The vertical vibration response of the first floor and the lateral response at each floor level were recorded at different construction stages. The evolution of the structural response as well as the generation of a finite element (FE) model is discussed. It was found that the addition of the non-load bearing facades increased the first floor natural frequency from 10.7 Hz to 11.4?Hz, a change of approximately +6.5%. Similarly these external facades resulted in the first sway mode having its frequency increased by 6%. The subsequent addition of internal partitions, mechanical services and furnishings resulted in the floor natural frequency reducing to 9.2 Hz. It is concluded that external facades have the net effect of adding stiffness and the effect of internal partitions and furnishings is to add mass. In the context of finite element modelling of structures there is a significant challenge to represent these non-structural elements correctly so as to enable the generation of truly predictive FE models.
    Scopus© Citations 14  525