Prevent disasters with structural measurements - Crystal Instruments provides high channel and portable solutions with remote monitoring online.
Structural Dynamics, the study of dynamic responses imparted on a structure, extends beyond the transportation industry (automobiles, helicopters, and planes) and general mechanical machinery (think of all the impacting and forces applied during the manufacture process of any product).
Buildings, bridges, and dams are large stationary structures that are equally as important as vehicles and manufacturing equipment when it comes to understanding the dynamics of a structure. We may not immediately think of such large stationary structures or infrastructure as ever having any movement. However, when movement occurs for various reasons, including earthquakes or vehicles passing over a bridge, we find the consequences can be disastrous if structural engineers did not consider the structural dynamics of the structure upfront during the construction process.
The Tacoma Narrows bridge is the classic example and cautionary tale found in nearly all introduction to dynamics textbooks. The bridge is a dramatic example of a design that failed to consider wind forces which excited one of the natural frequencies of the bridge. The bridge excitation sent the bridge into resonance that caused the bridge to buckle and ultimately collapse.
Since the collapse of the Tacoma Narrows bridge in November of 1940, many more recent structural dynamics measurements have been made on structures around the world including measurements on the Vieux Emosson Gravity Dam in Switzerland. A paper published in the late 90’s by S. Pietrzko, R. Cantieni, and Y. Deger with the EMPA, Swiss Federal Laboratories for Materials Testing and Research discusses the considerations for modal measurements on a large dam structure including excitation using a large servo-hydraulic exciter. The paper titled Forced Modal Test of the Vieux Emosson Gravity Dam… examines the added unique conditions of a structural test whereby a large mass of water sits right up against the structure under test.
Structural measurements on infrastructure are growing in demand given the aging buildings, bridges, and dams that populate countries around the world. Structural measurements are not the only measurements needed for aging infrastructure, but they do play a role. In the structural measurement category, Crystal Instruments offers products to measure and analyze data for large structure measurements like the measurements done on the Vieux Emosson Gravity Dam.
Crystal Instruments products provide users with high channel count capabilities that can be networked together and distributed over large distances. This is of the upmost importance to these types of structural measurements. Once the data is collected, it can then be quickly analyzed using any number of Crystal Instruments Experimental Modal Analysis (EMA) software tools including Operational Modal Analysis where a controlled force excitation may not be achievable.
This application note provides an introduction to the basic concepts of structural vibration. It presents the fundamentals and definitions in terms of the basic concepts. It also discusses practical applications and provides additional real world examples.