The steel girder bridge in West Dumai District is a bridge that connects two sub-districts, namely Dumai Kota Village and Pangkalan Sesai Village. The construction of this bridge is for the Dumai branch of Pelindo I's crude palm oil
transportation fleet, a container transportation route and a new road access for the people of Dumai City, namely from Jalan Fisherman Laut to Jalan Datuk Laksemana, which if the bridge If damaged, the economic activities of the surrounding area will be greatly hampered. In order to prevent premature damage, this research carried out a study to obtain the dynamic characteristics of the structure. Determining structural damage early is clearly very mportant because corrective action can be taken so that it is not dangerous in the future.The steel girder bridge was modeled in the SAP 2000 program to obtain theoretical dynamic
aracteristic parameters. For experiments using the
Experimental Modal Analysis (EMA) method. EMA is a method for estimating the dynamic characteristics of structures (natural frequencies, mode shapes, and damping ratios) based on artificial vibrations such as truck impacts coming from
ramps, hammers or vibrators. In this way, the influence of vibration on the dynamic characteristics of the Kuala Sungai Dumai Bridge structure can be obtained which can be used as a reference in identifying the structural health of the Kuala Sungai Dumai Bridge in the future.Research data recording uses an accelerometer sensor with five measurement points on the bridge floor plate. The recorded data is
processed using sensor connect software. The excitation used was a truck plus a load weighing 10 tons which was dropped from a 20 cm high ramp. The data taken is when the structure is in a free vibration conditions. The data that will be obtained is in the form of the structure's acceleration response 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 carried out, it was concluded that the natural
frequency of the bridge is in the range of 7 to 8 Hz, which shows that the Kuala Sungai Dumai Bridge meets the natural frequency value of the bridge based on the provisions of the Indonesian National Standard (SNI 1725:2016) and the Technical Guidelines for Bridges and Tunnels (Pd 024/BM/ 2011). And the relative damage value obtained for the bridge was 10%, based on the Technical Guidelines for Bridges and Tunnels Number Pt T-05-2002-B, it was concluded that the structural condition value of the Kuala Sungai Dumai Bridge was in fair condition with light damage (non-structural).

Key words: steel girder bridge, dynamic characteristics, Experimental Modal
Analysis