Keywords: cable-stayed pedestrian bridge, bridge static and dynamic loading tests, structures diagnostics, spectral analysis of structures, natural frequencies and modes.

Modeling and testing of the structures is only way of assessing the reliability of assumptions made in the numerical modeling and it is the most satisfactory means of determining relevant parameters for evaluation of existing structures. A comparison of the values of certain quantities obtained by experiment and by theoretical analysis and computation is the necessary prerequisite for both static and dynamic loading tests, respectively (SLT and DLT).

Cable-stayed bridges, especially pedestrian slender structures exhibit complex behavior in which the lateral translation, torsion and vertical bending modes are often strongly coupled. The combined spatial dynamic behaviour increases the challenges involved in the modelling. This strongly combined vibration under the pedestrian load requires dynamic and static load testing. This paper discusses the experimental and analytical analysis of the cable-stayed pedestrian bridge over the Hron river near Zarnovica (SK). Static and dynamic responses were obtained using static and dynamic loading tests [1]. Ambient vibration tests were also carried out to determine the service dynamic characteristics of the bridge and the basic modal parameters were identified in the frequency range 0.3 Hz to 10 Hz via spectral analysis [7]. The experimental investigation was complemented by development of a simplified Finite Element Model (FEM), so that the main assumptions adopted in model were assessed through the comparison between measured and designed dynamic and modal parameters [2,3,4].

The conclusions of this paper are:

1. The dynamic behavior of the pedestrian cable - stayed bridge confirmed good agreement between numerical (FEM) and experimental values of the static deflections (SLT).
2. The numerical model can be greatly affected by the sag of the cable and geometrical stiffness; if such effects are neglected in the FEM analysis, the resulting theoretical and experimental dynamic properties can be different, mainly during modal identification procedures.
3. The vibration under the common service load was safe but during monitoring of the bridge it sometimes appeared not comfortable for the pedestrian use.
4. Nowadays, the increased service vibrations are reduced by structural modifications following from the static and dynamic loading tests results [5,6].

1

Bencat, J., Report on static and dynamic test results of the cable - stayed pedestrian bridge over the Hron river, No. 6 - 3 - 20/SvF/06, ZU/Zilina, 2006.

2

ENV 1993 - 1- 4, EUROCODE 3:Design of steel structures. Supplementary rules for stainless steel.

3

Eurinox, Pedestrian bridges in stainless steel, Building series, Volume 7, Luxembourg, 2004.

4

The Steel Construction Institute, Structural design of stainless steel, SCI Publication P291, Ascot, UK 2001.

5

Slovak Standard No.73 6209 - Loading test of bridges.

6

Slovak Standard No.73 6203 - Loading of bridges.

7

Bendat, J.S; Piersol, A.G., Engineering applications of correlation and spectral analysis, (2nd edition), Wiley Interscience, New York, 1993.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £120 +P&P)