Penentuan Nilai Frekuensi Alami Struktur Pelat Lantai Jembatan Lengkung Menggunakan Metode Operational Modal Analysis (OMA)

The arch bridge at Riau Islamic University is the only access to the Faculty of Communication Sciences, if the bridge is damaged, activities at the Faculty of Communication Sciences will be greatly hampered. In order to prevent premature damage, in this study a study was carried out to obtain the natural frequency value of the curved bridge floor plate structure. Determining structural damage early is clearly very important because corrective action can be taken so that it is not dangerous in the future. The method used in this research is Operational Modal Analysis (OMA). Operational Modal Analysis (OMA) or also called Ambient vibration test is a method for estimating the dynamic characteristics of a structure (natural frequency, mode shapes, and damping ratio) based on vibrations generated from the operational conditions of the structure itself, such as vibrations from machine operations, wind, and etc. This technique is only the output that is measured for later use in the analysis Recording research data using accelerometer sensors with eight measurement points on the bridge floor plate. The recorded data is processed using sensor connect software. The data to be obtained is in the form of a response to the acceleration of the structure in the time domain. The response in the time domain is then transformed into the frequency domain using the Fast Fourier Transform (FFT) method. Based on the data analysis conducted, it was concluded that the natural frequency of the bridge is in the range of 6 to 7 Hz, which indicates that the UIR arch bridge meets the natural frequency value of the bridge based on the provisions of the Standar Nasional Indonesia (SNI 1725:2016)