Mexico City Soil’s Dynamic Characterization Through Ambient Vibration Tests. Importance for the Structural Design

Results of ambient vibration measurements performed with the H/V coefficient technique in different points along the 8 km projected trace of a semi-continuous vehicular bridge in Mexico City are presented. The results include the main natural period of the soil (Ts). Taking into account that the structural design of the bridge was performed with the modal spectral analysis method, the need to characterize the dynamic properties of the soil and of the structural system (natural periods, Ti) arises. A comprehensive comparison between Mexico City's Construction regulations (NTC) and the obtained estimations for the strategical selected points along the project's trace, which include different soil zones, is presented. This comparison exhibits the different dynamic properties that can be found in various soils along Mexico City, being the current soil's water extraction process one of the main causes. The results consider different ambient vibration tests performed before and after the construction of the bridge in order to obtain insights related to the structural dynamic behavior changes of this type of structures along their service life.