Structural Monitoring of a Tall Building Under Ambient Conditions and Earthquake

In regions with high seismicity such as Istanbul, it is necessary to determine the condition of tall buildings after an earthquake. Today, damage assessment after an earthquake is generally conducted by visual inspections. However, condition assessment of the buildings in a fast, remote and reliable way is important for both economy and public safety. Current condition of buildings can be assessed by controlling changes in dynamic properties and inter-story drift ratios quickly, remotely and objectively with Structural Health Monitoring (SHM) systems. With the motivations and reasons mentioned above, a tall building in Istanbul has been monitored continuously. Thanks to SHM system regularly recording vibration data of the structure, the earthquake of 5.7 magnitude occurred on September 26, 2019 in Marmara Sea was recorded. In this study, firstly, dynamic properties of the building before, during and after the earthquake were identified by using different identification techniques. After that, identified damping ratios of tall building were compared with several empirical equations in codes, guidelines and standards. Finally, Transfer Matrix Method (TMM) for Timoshenko beam model was utilized to estimate the accelerations of non-instrumented floors from instrumented floors and predict inter-story drift ratios.