This week workshop is about the characteris1cs of mass construc1ng. By using same size uniformed blocks, students are asked to build a tower with a door. As one can see form this picture, most students chose build in this way with a “door ”in the front.
T h e s t r u c t u r e b e c a m e unstable as the perimeter decreasing.
The reason this structure can hold is because blocks are transferring down the load. Load path of this structure is illustrated in the picture.
The ini1al method was to put the next layer a liBle inner than the pervious layer. But because the center of gravity in this case is not on the structure itself, an external force had to be applied to stable the structure. However, as more blocks was put on top of the original blocks, the structure became stabilized.
S i n c e a l l b l o c k s a r e uniformed, as the diameter decreasing, the number of blocks needed in each layer decrease. However, in most c a s e s , t h e d i ff e r e n c e between two layers is smaller than one block, therefore, turning one (or several if necessary) into ver1cal posi1on can help the structure closing.
The structure also became unstable if contractual m a t e r i a l i s n o t w e l l organized. The picture on the leI shows when the blocks was put both in ver1cal way and no block across each other on two layers, this part disturbed the way this structure transfers its load. However, as a mass structure, the influence is miner.
The structure has been proven to be very stable. As mass structure, load is being transferred down by all units, therefore, the removal of part of the structural will not influence the stability of the whole structure.
The sketch on the leI shows the load path of an s t r u c t u r e w i t h a n opening. The structure remain stable is because the load can s1ll be transferred into ground and the center of gravity is s1ll within the load path of the structure. However, if the shaded part is missing, the structure will collapse as the center of gravity is outside the structure.
The difference between these two structures is the first structure is straighter; therefore, it is easier to fine the center of gravity. The second structure tried to be more athle1cal, hence the centre of gravity is changed to one edge of the structure instead of the centre of it. When load is placed, it is difficult to put the gravity centre of the load line up with the gravity centre of the structure, therefore, the structure collapse.
The second one is proved to be less stable. The circled part is the most fragile part as the line of gravity pass through the edge of this part.
Load path: the direc1on in which each consecu1ve load will pass through connected members Masonry: Brick, concrete, stone, ar1ficial stone or terra coBa laid in mortar (common construc1on terms, 2014). Dead load: sta1c loads ac1ng ver1cally downward on a structure, comprising the self-‐weight of the structure and the weight of building elements, fixtures and equipment permanently aBached to it. (Ching, 2008, page 2.08) Point load:is a force applied at a single infini1smal point at a set distance from the ends of the beam. Uniform distributed load (q) is a force applied over an area, denoted by q which is force per unit length (Defini1ons, 2014). Beam: rigid structural members designed to carry and transfer transverse loads across space to suppor1ng elements. (Ching, 2008, page 2.14)
Reference list:
Ching, F. D. (2014). Building construc.on illustrated. John Wiley & Sons. Common construc.on terms, HSC online. (2014, August). Retrieved from: hBp://www.hsc.csu.edu.au/construc1on/glossary/3246/common_terms.htm#P Defini.ons, Elas.c Beam Deflec.on Calculator. (2014, August). Retrieved from: hBp://www.aps.anl.gov/APS_Engineering_Support_Division/ Mechanical_Opera1ons_and_Maintenance/Calculators/defini1ons.html