Options
Li, Yingyan
Preferred name
Li, Yingyan
Official Name
Li, Yingyan
Research Output
Now showing 1 - 6 of 6
- PublicationThe influence of speed on the dynamic amplification of two loads crossing a simply supported bridgeIt is possible to use statistical data for the determination of traffic load models for the design of bridges. For existing bridges, traffic simulations based on measured traffic data, can provide a more accurate prediction of the characteristic load effect for assessment purposes. However, this procedure only provides the characteristic static loading or load effect. The total static-plus-dynamic load is often estimated based on conservative factors due to the high degree of uncertainty involved in the dynamic interaction between traffic, road profile and bridge. This paper aims to reduce this uncertainty by using simple dynamic models to obtain an understanding of the speeds and axle spacings that cause the highest dynamic amplifications.
132 - PublicationCritical speed for the dynamics of truck events on bridges with a smooth road surface(Elsevier, 2010-05-24)
; ; ; ; ; Simple numerical models of point loads are used to represent single and multiple vehicle events on two-lane bridges with a good road profile. While such models are insufficiently complex to calculate dynamic amplification accurately, they are presented here to provide an understanding of the influence of speed and distance between vehicles on the bridge dynamic response. Critical combinations of speed as a function of main bridge natural frequency and meeting point of two vehicles travelling in opposite directions are identified. It is proposed that such simple models can be used to estimate the pattern of critical speeds versus dynamic amplification for heavy trucks on a bridge with a relatively smooth surface. The crossing of a three-dimensional spring-dashpot truck is simulated over a bridge plate model to test this hypothesis for a range of road roughness. Further validation is carried out using the site-specific mean pattern associated to field measurements due to the passage of a truck population. The latter is found to be closely resembled by the theoretical pattern derived from simple point load models.1574Scopus© Citations 22 - PublicationThe use of vehicle acceleration measurements to estimate road roughness(2008-06)
; ; ; Road roughness is a broad term that incorporates everything from potholes and cracks to the random deviations that exist in a profile. To build a roughness index, road irregularities need to be measured first. Existing methods of gauging the roughness are based either on visual inspections or using one of a limited number of instrumented vehicles that can take physical measurements of the road irregularities. This paper proposes the collection of data from accelerometers fixed in a specific vehicle type and the use of this data to estimate the road condition. Although the estimate is approximate, accelerometers are being increasingly used by car manufacturers to improve suspension performance and the proposed method is relatively inexpensive to implement and provide road managers with constantly updated measurements of roughness. This approach is possible due to the relationship between the power spectral densities of road surface and vehicle accelerations via a transfer function. This paper shows how road profiles can be accurately classified using axle and body accelerations from a range of simulated vehicle-road dynamic scenarios.10021Scopus© Citations 225 - PublicationWavelet domain analysis for identification of vehicle axles from bridge measurementsBridge Weigh-In-Motion (B-WIM) is a process by which the axle and gross vehicle weights of vehicles travelling at highway speeds can be determined from instrumented bridges. The traditional method of attaching strain transducers to the soffit of the bridge and placing axle detectors on the road surface has been replaced here by using additional transducers underneath the bridge for axle detection and Nothing-On-the-Road (NOR). This paper presents a wavelet based analysis of strain signals and shows the efficacy of using wavelets in pattern recognition of these signals. The transformed signals are used to identify axle passage and hence the vehicle velocity and the axle spacing. In addition to numerically generated strains, signals acquired from such a NOR instrumentation of a bridge in Slovenia have been analysed by the method of wavelet transformation to extract axle position information that was not readily detectable using existing methods.
1171Scopus© Citations 88 - PublicationBridge roughness index as an indicator of bridge dynamic amplificationThe concept of a road roughness index for bridge dynamics is developed. The International Roughness Index (IRI) is shown to be very poorly correlated with bridge dynamic amplification as it takes no account of the location of individual road surface irregularities. It is shown in this paper that a Bridge Roughness Index (BRI) is possible for a given bridge span which is a function only of the road surface profile and truck fleet statistical characteristics. The index is a simple linear combination of the changes in road surface profile; the coefficients are specific to the load effect and span of interest. The BRI is well correlated with bridge dynamic amplification for bending moment due to 2-axle truck crossing events. A similar process can be used to develop a BRI for trucks with other numbers of axles or combinations of trucks meeting on a bridge.
Scopus© Citations 27 911 - PublicationThe development of a dynamic amplification estimator for bridges with good road profilesThe paper considers the influence of the surface profile on the dynamic amplification of a simply supported bridge when subject to a quarter car vehicle model. The effect of the profile irregularities on the bridge dynamic amplification is characterized with a ‘response surface’ giving dynamic amplification due to a ‘unit ramp’ at any location. Even though the dynamic interaction problem is non-linear, the effects of all ramps which together make up a road profile can be calculated separately and added using the ‘response surface’. This superposition process achieves reasonable accuracy for ‘good’ (moderately smooth) surface profiles. An accurate estimate of dynamic amplification for bridges is demonstrated with a wide range of good profiles.
807Scopus© Citations 32