Vol. 9, Issue 11, Part D (2023)

Abstract
The period of vibration of a structure is a very important property in structural calculations. Because the structure's vibration period will determine how much earthquake load is applied in the structure design process. The North Sulawesi region is an earthquake area with a high risk. The vibration time formula used is based on SNI 03 - 1726 – 2012 adopted from the ASCE earthquake regulations and the formula proposed by Goel and Chopra (1997). The proposed structural period formula in SNI 03 – 1726 – 2012 has the weakness of treating each earthquake zone zone for both high and low risk areas. This research study aims to formulate the structure period designed according to the SNI 03 - 1726 - 2012 Building earthquake regulations and determine the influence of concrete quality on the structure period. Research Method for Modeling 3 Dimensional Structures in Regular Buildings with a height between floors of 4m and a width of 4m, Reinforced Concrete Structure Building Category, 12 Floor Mid Rise Building. To realize this in real buildings, the Etabs Program is used in Structural Modeling. After obtaining the results of the Structure Period values, a regression analysis is made to obtain the best formula value. The results of the regression analysis showed that the 2 best formulas were based on a correlation value of 98%. From the research results, the recommended formula is T = 0.105 H0.785, T = 0.311 n0.785. The Influence of Concrete Quality on the Structure Period. The smaller the Concrete Quality, the greater the increase in the Structure Period, the impact on the structure period which is small. Concrete Quality affects the Period of the Structure.