STUDIES FOR CONTROLLING HUMAN-INDUCED VIBRATION OF TWO NIELSEN-TRUSS FOOTBRIDGES IN MALAGA (SPAIN)

摘要

This paper describes the design, construction and dynamic control of two new Nielsen-Trussrnfootbridges in Malaga (Spain), over two important highways, MA-21 and A-7. The footbridges arerntwo Nielsen-Truss footbridges of different spans between 45 and 70 m, with a reduced variablerndepth decreasing from the centre to the end. It was no possible to make a static test of thernfootbridges, so the client has asked for a dynamics and modal analysis test. This was based onrnanalysing the response of the structure to human-induced dynamic loading by pedestrian movementrn(walking, running or jumping). Vibrations derived from such human-induced loads can causerndisturbance to pedestrians or, in some cases, resonance of the structure. Different phenomena can tornlight through these tests, looseness in footbridge articulations, solid friction on the expansion jointsrnand sliding bearings. The performance of the test has considered the identification of critical naturalrnfrequencies and damping ratios, the measurement of response induced by one pedestrian, thernmeasurement of the response induced by a small group of pedestrians and the measurement of thernresponse induced by a continuous flow of pedestrians. These analyses were then used to re-verifyrnthe structural project.