scholarly journals The Effect of Pedestrian Traffic on the Dynamic Behavior of Footbridges

10.14311/536 ◽  
2004 ◽  
Vol 44 (2) ◽  
Author(s):  
M. Studničková
Keyword(s):  
Dynamic Response ◽  
Dynamic Behavior ◽  
Prestressed Concrete ◽  
Bridge Deck ◽  
Natural Frequencies ◽  
Limit States ◽  
Pedestrian Traffic ◽  
Ultimate Limit ◽  
Comfort Criteria

The dynamic response of a footbridge depends namely on the natural frequencies of the structure in vertical, in horizontal and in torsion. If any of the frequencies in vertical is in the range 1.0 Hz to 3.0 Hz, the dynamic response from moving people can be significant. In this case it is necessary to calculate vibrations taking into account both serviceability and ultimate limit states. The same problem arises when any of the frequencies in horizontal (transversal) or in torsion are in the range 0.5 Hz to 1.5 Hz. Such frequencies haveare found namely in footbridges with larger spans or cable-stayed and suspension footbridges.A unique cable-stayed footbridge with prestressed concrete was dynamically analyzed and the dynamic response to simulated pedestrian loading was calculated. The calculated effects were compared with the pedestrian comfort criteria for serviceability limit states. These criteria are defined in terms of maximum acceptable acceleration of the bridge deck.

scholarly journals Some relevant aspects of footbridge vibrations

2002 ◽  
Vol 2 (4) ◽  
pp. 281-289
Author(s):  
Ana Spasojevic ◽  
Djordje Djordjevic ◽  
Marija Spasojevic ◽  
Novak Spasojevic
Keyword(s):  
Structural Design ◽  
Natural Frequencies ◽  
Weight Ratio ◽  
Structural Systems ◽  
Live Load ◽  
Limit States ◽  
Codes Of Practice ◽  
Vibration Serviceability ◽  
Bridge Structures ◽  
Ultimate Limit

Considering the contemporary structural inaterials that are becoming more resistant, having higher strength to weight ratio, and the fact that live load of footbridges is low, the design based on static analysis only, respecting ultimate limit states requirements, leads to slender bridge structures for pedestrian and cycle track use. As a consequence, stiffness and masses decrease, facing lively, easy to excite structures, with smaller natural frequencies. The excitation of a footbridge by a pedestrian passing over it can be unpleasant for a person walking or standing on the bridge, but usually not destructive for the structure itself. Recent experiences regarding dynamic behavior of slender footbridges have especially shown that vibration serviceability limit states are very important requirements in any structural design. We are presenting a general algorithm for analytical testing of dynamic parameters of structures, calculation of deflection, thus speed and acceleration of superstructure under human-induced excitation, as predicted by Eurocode, British and Canadian standards in use, since no Yugoslav code deals with the problem. The evaluated system is a footbridge in a system of a simply supported concrete girder. The presented model is used to show correspondence of results, obtained by the algorithm, with the results obtained using the simplified methods suggested by the Codes of Practice, since the latter exists only for certain structural systems.

scholarly journals Reliability-based conversion of a structural design code for railway prestressed concrete sleepers

2011 ◽  
Vol 226 (2) ◽  
pp. 155-173 ◽  
Author(s):  
A M Remennikov ◽  
M H Murray ◽  
S Kaewunruen
Keyword(s):  
Dynamic Response ◽  
Prestressed Concrete ◽  
Design Method ◽  
Railway Track ◽  
Material Strength ◽  
Dynamic Resistance ◽  
Limit States ◽  
Wheel Load ◽  
Head Surface ◽  
Current Design

Ballasted railway track is very suitable for heavy-rail networks because of its many superior advantages in design, construction, short- and long-term maintenance, sustainability, and life cycle cost. An important part of the railway track system, which distributes the wheel load to the formation, is the railway sleeper. Improved knowledge has raised concerns about design techniques for prestressed concrete (PC) sleepers. Most current design codes for these rely on allowable stresses and material strength reductions. However, premature cracking of PC sleepers has been found in railway tracks. The major cause of cracking is the infrequent but high-magnitude wheel loads produced by the small percentage of irregular wheels or rail-head surface defects; both these are crudely accounted for in the allowable stress design method by a single load factor. The current design philosophy, outlined in Australian Standard AS1085.14, is based on the assessment of permissible stresses resulting from quasi-static wheel loads and essentially the static response of PC sleepers. To shift the conventional methodology to a more rational design method that involves a more realistic dynamic response of PC sleepers and performance-based design methodology, comprehensive studies of the loading conditions, the dynamic response, and the dynamic resistance of PC sleepers have been conducted. This collaborative research between several Australian universities has addressed such important issues as the spectrum and the amplitudes of dynamic forces applied to the railway track, evaluation of the reserve capacity of typical PC sleepers designed to AS 1085.14, and the development of a new limit states design concept. This article presents the results of the extensive analytical and experimental investigations aimed at predicting wheel impact loads at different return periods (based on field data from impact detectors), together with an experimental investigation of the ultimate impact resistance of PC sleepers required by the limit states design approach. It highlights the reliability approach and rationales associated with the development of limit states and presents guidelines pertaining to conversion of AS 1085.14 to a limit states design format. The reliability concept provides design flexibility and broadens the design principle, so that any operational condition could be catered for optimally in the design.

scholarly journals Estados limites determinantes no dimensionamento da armadura longitudinal de vigas pós-tracionadas sem aderência

2020 ◽  
Vol 1 (51) ◽  
pp. 226
Author(s):  
João Paulo Boff Almeida ◽  
Renato Silva Nicoletti ◽  
Anderson Renato Vobornik Wolenski ◽  
Rafael Lemes Bezerra ◽  
Alex Sander Clemente de Souza ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Limit State ◽  
Ultimate Limit State ◽  
Longitudinal Reinforcement ◽  
Structural Elements ◽  
Limit States ◽  
The Common ◽  
Lower Height ◽  
Ultimate Limit ◽  
Range Of Values

<p>In the design of prestressed concrete structural elements, due to the fact that prestressing introduces actions in the structure, the limit states of crack formation service (SLS-F), decompression (SLS-D), and the ultimate limit state in the act of prestressing (ULS-ACT) are determinants in the dimensioning of the longitudinal reinforcement (Ap). In most cases, the longitudinal reinforcement required for the limit states is not exact, and the solution, if any, is within a range of values defined by the voltage limits of the SLS-F, SLS-D, and ULSACT. In this context, this paper aimed to verify, analytically, the limit states, service or ultimate, determinants in the calculation of Ap of unbonded post-tensioned beams. For this purpose, beams with material properties, environmental conditions, the width of the cross-section, and identical loads (except for their own weight) were analyzed, varying the height between 50 and 70 cm. It was found that the limits of tensile stress in the SLS-D and compression in the ULS-ACT for the lower edge, defined the intervals that were requested, simultaneously, by SLS-F, SLS-D, and ULS-ACT. For beams of lower height, the common range of solutions became more restricted and the ULS became decisive in the dimensioning of the longitudinal reinforcement, which did not occur for the higher beams.</p>

Full Depth Precast and Precast, Prestressed Concrete Bridge Deck Panels

PCI Journal ◽  
1995 ◽  
Vol 40 (1) ◽  
pp. 59-80 ◽  
Author(s):  
Mohsen A. lssa ◽  
Ahmad-Talalldriss ◽  
lraj I. Kaspar ◽  
Salah Y. Khayyat
Keyword(s):  
Prestressed Concrete ◽  
Bridge Deck ◽  
Concrete Bridge ◽  
Deck Panels ◽  
Concrete Bridge Deck ◽  
Prestressed Concrete Bridge ◽  
Precast Prestressed Concrete

Pull-Out Performance of T-Stub End Plate Connected To Concrete Filled Thin-Walled Steel Tube (CFTST) using Lindapter Hollo-Bolts

2018 ◽  
Vol 15 (1) ◽  
pp. 59
Author(s):  
NAZRUL AZMI AHMAD ZAMRI ◽  
CLOTILDA PETRUS ◽  
AZMI IBRAHIM ◽  
HANIZAH AB HAMID
Keyword(s):  
Limit Load ◽  
Steel Tube ◽  
Limit States ◽  
End Plate ◽  
Pull Out ◽  
Pullout Load ◽  
Thin Walled ◽  
Stub End ◽  
Concrete Filled Steel Tubes ◽  
Ultimate Limit

The application of concrete filled steel tubes (CFSTs) as composite members has widely been used around the world and is becoming popular day by day for structural application especially in earthquake regions. This paper indicates that an experimental study was conducted to comprehend the behaviour of T-stub end plates connected to concrete filled thin-walled steel tube (CFTST) with different types of bolts and are subjected to pullout load. The bolts used are normal type bolt M20 grade 8.8 and Lindapter Hollo-bolt HB16 and HB20. A series of 10 mm thick T-stub end plates were fastened to 2 mm CFTST of 200 mm x 200 mm in cross-section. All of the specimens were subjected to monotonic pull-out load until failure. Based on test results, the Lidapter Hollo-bolts showed better performance compare to normal bolts. The highest ultimate limit load for T-stub end plate fasten with Lindapter Hollo-bolt is four times higher than with normal bolt although all end plates show similar behaviour and failure mode patterns. It can be concluded that T-stub end plate with Lindapter Hollo-bolt shows a better performance in the service limit and ultimate limit states according to the regulations in the design codes.

Dynamic Response of the Steel Bridge Deck Thin Surfacing due to Vehicle Load

2010 ◽  
Vol 156-157 ◽  
pp. 677-677
Keyword(s):  
Dynamic Response ◽  
Bridge Deck ◽  
Advanced Materials ◽  
Steel Bridge ◽  
Vehicle Load ◽  
Materials Research

This paper has been published in Advanced Materials Research Volumes 148 - 149, pp 544 http://www.scientific.net/AMR.148-149.544

Influence of the backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set

2016 ◽  
Vol 231 (11) ◽  
pp. 2025-2041 ◽  
Author(s):  
Shijing Wu ◽  
Haibo Zhang ◽  
Xiaosun Wang ◽  
Zeming Peng ◽  
Kangkang Yang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Planetary Gear ◽  
Tooth Wear ◽  
Transmission Error ◽  
Gear Transmission ◽  
Tooth Surface ◽  
Contact Ratio ◽  
The Impact

Backlash is a key internal excitation on the dynamic response of planetary gear transmission. After the gear transmission running for a long time under load torque, due to tooth wear accumulation, the backlash between the tooth surface of two mating gears increases, which results in a larger and irregular backlash. However, the increasing backlash generated by tooth accumulated wear is generally neglected in lots of dynamics analysis for epicyclic gear trains. In order to investigate the impact of backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set, in this work, first a static tooth surface wear prediction model is incorporated with a dynamic iteration methodology to get the increasing backlash generated by tooth accumulated wear for one pair of mating teeth under the condition that contact ratio equals to one. Then in order to introduce the tooth accumulated wear into dynamic model of compound planetary gear set, the backlash excitation generated by tooth accumulated wear for each meshing pair in compound planetary gear set is given under the condition that contact ratio equals to one and does not equal to one. Last, in order to investigate the impact of the increasing backlash generated by tooth accumulated wear on dynamic response of compound planetary gear set, a nonlinear lumped-parameter dynamic model of compound planetary gear set is employed to describe the dynamic relationships of gear transmission under the internal excitations generated by worn profile, meshing stiffness, transmission error, and backlash. The results indicate that the introduction of the increasing backlash generated by tooth accumulated wear makes a significant influence on the bifurcation and chaotic characteristics, dynamic response in time domain, and load sharing behavior of compound planetary gear set.

DYNAMIC BEHAVIOR OF TELESCOPIC CRANES BOOM

2013 ◽  
Vol 13 (01) ◽  
pp. 1350010 ◽  
Author(s):  
IOANNIS G. RAFTOYIANNIS ◽  
GEORGE T. MICHALTSOS
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Analytical Model ◽  
Constant Velocity ◽  
Steel Beam ◽  
Continuum Approach ◽  
Theoretical Formulation ◽  
Modal Superposition ◽  
Superposition Technique

Telescopic cranes are usually steel beam systems carrying a load at the tip while comprising at least one constant and one moving part. In this work, an analytical model suitable for the dynamic analysis of telescopic cranes boom is presented. The system considered herein is composed — without losing generality — of two beams. The first one is a jut-out beam on which a variable in time force is moving with constant velocity and the second one is a cantilever with length varying in time that is subjected to its self-weight and a force at the tip also changing with time. As a result, the eigenfrequencies and modal shapes of the second beam are also varying in time. The theoretical formulation is based on a continuum approach employing the modal superposition technique. Various cases of telescopic cranes boom are studied and the analytical results obtained in this work are tabulated in the form of dynamic response diagrams.

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