WEEK 2 JOURNAL ENTRY
CHAN JOSHUA TIG HAY 638994
CONSTRUCTION PROCESS STAGE 1: LAYING OUT THE FOUNDATION
The team believed that by adopting a triangular form the tower would be more resistant to lateral loads compared to a rectangular base. The length of each side of the triangular base was limited to roughly 22cm.
The tower itself has smaller length per side than its base such that columns could be erected to support the tower itself.
The initial idea for the towerâ€™s foundation was a triangular base, acting as a support to the tower, which was decided to be a triangular column.
STAGE 2: FRAME AND BRACING EMPLOYEMENT
The triangular column approach was similar to adopting a rigid framework where columns and beams are connected with hinges. The wooden strips, which acted as the columns, were connected using superglue and masking tape. Therefore the frame elements share the moment distribution and the whole framework is subject to lateral loads.
The team had access to long thin strips of about 30cm and thus they are highly subject to buckling. Therefore the team decided to adopt lateral bracing with shorter strips to increase the stiffness of the framework. Instead
Cross bracing increases the resistance of the tower towards lateral loads
CHAN JOSHUA TIG HAY 638994
CONSTRUCTION PROCESS After the team ran out of long wooden strips to progress upwards, some shorter strips leftover as well as masking tape were utilized to strength areas where bracing was not present.
Strong Bracing enabled the upper part of the tower to remain in one piece and resistant to buckling
STAGE 3: COLLAPSE The towerâ€™s framework failed when the tutor placed two objects on to the tower, they include a bottle of hand cream and a spectacles case.
Buckling was observed near the foundation of the tower. It was obvious that bracing was not present in the cracked area and this was believed to be the trigger of the collapse.
On the other hand, other than the cracking of the particular spot, the rest of the tower remained unharmed. This showed that the tower was not affected by crushing, but was merely affected by the buckling of a single column without bracing. CHAN JOSHUA TIG HAY 638994
ACTIVITY ANALYSIS The activity achieved the goal of conveying the significance of bracing in the creations of different framework in the construction process. It is concluded that bracing is the dominant factor in load support not only from gravity but lateral loads as well. At the same time, how joints affect the frame element was evident. By using glue or masking tape, frame elements were combined into one and failed to achieve a post and beam framework.
FRAME SYSTEM The frame system adopted in this activity is a rigid framework. The frame functions as a continuous structural unit instead of individual elements, this causes the frame to be more subject to larger deformations brought about by lateral loads.
EFFICIENCY OF MATERIAL Balsa wood used in the activity was light and stiff. However, as they were cut into long and small thin strips, each of the strips had a very small cross-sectional area, thus making them vulnerable to buckling.
Published on Aug 15, 2013