Ambient vibration testing of low and medium rise infilled RC frame buildings in Jordan

• Measured periods of infilled RC frame buildings are shorter than those given by the Jordanian code.
• Analytical period values showed large differences with the measured and code values.
• A period–height relation is proposed for infilled RC frame buildings in Jordan.

This study aims at investigating the fundamental period of vibration of infilled RC frame buildings using measurements of ambient vibrations and numerical analyses. Ambient vibrations were measured at the roof level of 29 selected buildings with heights of one to six stories. Using Nakamura technique, the horizontal-to-vertical spectral ratio curves were obtained in the two orthogonal building directions. The estimated period values ranged between 44% and 91% of elastic periods suggested by the local code. Preliminary period–height relations were proposed using regression analysis of the measured periods. Limited by the availability of structural details, the periods of vibration of 15 buildings only were evaluated using linear modal analysis of three dimensional computer models including the effect of stone–concrete infills. Considering cracking of the structural concrete elements increased the period of vibration by 40–50% compared to the elastic value. Analytical period values showed large differences with both the measured and code values.