Fatigue Tests of Assembly Joints of Truss Main Girders of Temporary Footbridge for Pedestrians and Cyclists

Abstract

The paper is focused on the problems of the actual fatigue resistance of assembly joints of the temporary footbridge, which is newly developed in the authors workplace. The necessity of the development of a new temporary footbridge has been invoked by the lack of such constructions in a practice, both in the case of flood situations, and also as the site facilities. Within this work the attention is paid to static and structural design, mainly to the harmonization of both aspects, to achieve the efficient design. In parallel, two types of the footbridge are developed, both ones with a lower deck, truss main girders and bracings. The first structure short footbridge can reach up to 18 m span; the second structure long footbridge reaches up to 36 m span. This paper deals with some problems of the short footbridge fatigue and presents the basic information on the actual behaviour of assembly joints of the structure in the case of fatigue loading actions. The paper is focused on the fatigue tests of assembly joints including elaboration and evaluation of their main results.

Fatigue Resistance and Durability of New Mechanical Connections of Currently Developed Temporary steel Footbridges and Railway Bridges

“…3b. The overview of fatigue tests results, including basic loading parameters applied during fatigue tests is in Table 1 -for more see [3].…”

“…The direct results are the numbers of repeated loading cycles reached at the fatigue failure. The overview of all tested specimens, including basic loading parameters applied during fatigue tests, and mainly the resulting number of cycles is listed in Table 2 -for more see [4]. Because the most failure type was the failure of pins and until subsequently the failure of other parts occurred, that failure of pins has been taken as default for the evaluation of cyclic fatigue tests.…”

“…The procedure [for more applications see 1, 3,4] for the determination of the differences of extremes of the force of one loading cycle contains the gradual determination of the following quantities and parameters: parameters , of the regression line for the failure probability of 50 %; amplitude of the force FP for NC = 2 · 10 6 ; left-prediction limit FP (respectively log FP); the difference of loading force extremes of one cycle F on the fatigue limit for 2 million cycles.…”

“…In the first step of the elaboration, the test results obtained have been evaluated from the viewpoint of the load amplitude in relation to the number of loading cycles, to obtain the simple fatigue strength only [1,3,4,7,8]. In the second step of the elaboration, the test results have been statistically and probabilistically evaluated, to obtain the reliable fatigue strength, also with regards to the test number and the required level of the reliability [1,3,4,6,9].…”

“…All these joints have been designed using pins and plates. Within their investigation, the fatigue tests of assembly joints namely of lower chords, which are subjected to the tensile force, have been performed [3,4,5].…”