i'm the admissions tutor for the civilengineering department and we're here today at the collaborative teachinglaboratory at the civil and mechanical engineering building we've got variousactivities going on today i'm showing you different aspects of civil engineeringas you can see and here i'd like to show you one of the demonstrations that wehave set up about the earthquake engineering so what we have here is ashaking table and a control system and in order to study the impact ofearthquakes and different structures and different buildings what i have donehere i've put two different buildings two different structures andone is shorter than the other one and
i'm going to study using this controlsystem and the shaking table what would happen if i apply differentfrequencies due to these structures and so for example i'm going to start byapplying a frequency of 2.15 hertz and then an amplitude of 1 centimetreand then i'm just going to give this a go and see what happens so you can seevery shortly that the the shortest structure will start to vibrate excessively and the reason for that isthat i've picked a frequency for the loading very near or close to thenatural frequency of the structure now if i change that slightly and then gofor a lower frequency
somewhere near 1 hertz, right,very shortly you will see that the surface structure gradually stopped andthen it's the longer one that starts to vibrate and that's because the frequencyof the loading is closer to the natural frequency of the taller building so howdoes that have an impact on our civil engineering civil engineers' job so whenyou design or analyze a structure you need to design it in a way that you pickthe right natural frequency using by choosing the right materials and rightgeometry and right sizes so that when you have a wind or a lateral load or anearthquake it won't be affected it won't collapse it so we've got loads of otheractivities going on today here please
come and have a have a look we're hereuntil 4 o'clock and basically that says hope to see you here