Modern construction methods allow increasingly leaner structures. However, this increases the sensitivity with respect to dynamic excitation. Müller-BBM also provides consulting in the area of typical structural dynamics relative to Vibration and Shock Protection.
Signs of wear and other damage to the machine are not always visible, and the operation of machinery may lead to vibrational effects in the environment that could cause a nuisance to adjacent residences and work places, even at greater distances. We assess suitable isolated machine bases and record their dynamic behaviour.
Tall, slender bell towers are often susceptible to the excitation caused by the chimes. This is usually triggered by a resonance situation in which the first bending frequency of a tower is excited by the bells vibrations. Proof with respect to a vibrational excitation in accordance with DIN 4178, specifically for bell towers must therefore be provided. This applies not only to new buildings but also to historical towers that are equipped with a new peal or are influenced by their dynamic behaviour due to renovation, remodelling or structural changes due to ageing.
The phenomenon is very familiar: Solid bridges can be excited to high vibration amplitudes by marching columns in step. By default, the susceptibility to vibrations of pedestrian bridges from a span of roughly 30m are now being verified. In individual cases long-span building floors or very light building ceilings for office, residential and hotel use, in gyms, ceilings, balconies, terraces or in concert or event venues must also be examined in detail. The use of dampened vibration absorbers, for example, is now a proven and state-of-the-art method.
Aeroelastic excitation can occur in slender components by wind gusts or periodic vortex shedding. Self-excited vibrations may also occur through interaction with the building.
In Germany, the probabilistic reassessment of damage scenarios compared to the geological situation has resulted in an increase in the presumed earthquake loads. In contrast, both the classical response spectrum method and proof provided by the time domain method are accepted, where non-linearities can be taken into account explicitly. In addition to building construction, plant constructions worldwide are affected, whereby high demands placed on them in case of disaster in order to guarantee a highly reliable supply and to avoid damage to the environment.
Based on many years of experience with these issues, Müller-BBM provides evidence of the usability of the affected structures and supports the responsible structural engineers by identifying the likely dynamic loads for the detection of viability.
Since in many cases, such as pedestrian-induced vibrations neither detection methods nor defined limits in the standards or guidelines exist, Müller-BBM draws up expert reports with risk assessments based on various stress scenarios. Building dynamics provides the possibility to have a detailed diagnosis using well-developed and relatively easy to implement measurement techniques. Forecasting method based on the experience gained are more significant with the use of efficient computers. Through the use of advanced simulation methods that are based on measured data, such as Model Updating , we achieve very reliable predictions.
These results are used as the basis for planning and consulting on the implementation of any measures needed for vibration reduction.