4.1 Key findings
From the data collected, it was clearly found that the damper worked in reducing the horizontal shake for the third and top floor of every building (Fig. 21, 22 and 23) . It is, however, not effective in reducing the shake of the base, first and second floors of the towers. Fig. 18, 19 and 20 also show that “X” bracings reduce the shake of the building the most amongst the “X”, “SLASH” and “NONE” bracings. (Note that F0 is not used in the comparison as no bracings were built for the base). As for the beam sets, there were very little effects on the shake of the building. (Note that F0 is not used, once again, as F0 is made up of the square wooden base board and not the horizontal beams). This suggests that the number of beams used do not affect the earthquake resistance of a building.
4.2 Explanation of key findings
As the building oscillates during an earthquake, the top of the building will vibrate the most as the most oscillation waves will be reflected back down to the bottom of the building while the rest of the oscillation waves will become airborne or converted into other energy such as sound and heat. As the building begins to shake, the dampers would move back and forth to compensate for the vibration of the shock. For example, as a particular building moves to the left, the damper remains still as it has inertia. When the building shakes to the right, the damper will shake to the left, countering the movement of the building (Hwang, 2002). This supports our findings that the damper reduce the shake of top floors of the buildings.
As for the bracings, our findings state that “X” bracings reduce the shake of the building the most amongst the three bracings. This is supported by IDEERS (n.d.) which states that cross bracings only need to resist tension, as one brace resists horizontal forces in one direction, while the other brace resists when the the horizontal forces in the other direction.
Beams and columns (ie. the vertical and horizontal elements of a building) are built integrally with each other. Thus, under the action of loads, they act together as a frame transferring forces from one to another. However, according to ArchExamHandbook (2011), beams are mostly used to resist vertical forces (eg. gravitational force), and less for horizontal forces (forces from earthquakes and wind).
4.3 Evaluation of hypothesis
Hypothesis 1: The greater the number of beams used to make up each floor, the less the acceleration of the horizontal shake of the tower.
The hypothesis was shown to be wrong. Our findings suggest that the number of beams used to make up each floor do not affect the acceleration of the horizontal shake of the tower.
Hypothesis 2: The “X” bracings work the best (least acceleration of the horizontal shake of the tower) as compared to no bracings and the “SLASH” bracings.
This hypothesis was proven to be correct. Our findings show that using the “X” bracings in a building causes the building to have less horizontal shake than using the “SLASH” bracings and using no bracings.
Hypothesis 3: If the damper is present, the acceleration of the horizontal shake of the tower should decrease.
This hypothesis is partially correct. Only the horizontal shake of the top two floors of the tower decreased. The acceleration of the horizontal shake of the base, first and second floors of the tower did not decrease.
4.4 Areas for improvement
There are a few thing which can be improved on.
First, the process of making the buildings can be improved. While making the buildings, there would have been minor differences and errors such as the amount of glue used to secure each joint. This might affect the results. Thus, automated glue dispensers can be used or professionals can help to make these buildings.
Second, another linear motor could be purchased in order to conduct tests for the x-axis and the z-axis. A step motor could also be used to alter the speed of the shake so that the graphs will have more resemblance to the graph of an actual earthquake.
Another area of improvement is the way that the experiments were conducted. The current experimental process requires manually clicking pause on the QCNLive software. As there were 5 macbooks, at least 3 people were needed for each experiment. Thus, this could cause an error as a result of different reaction times. In order to prevent this error, new applications, which are better than QCNLive and have automatic functions such as an “auto-stop” function, can be used.