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Constructing Environments Logbook Abhishek Rajendran Student ID: 698670 Tutorial No. 4




Due to   time   constraints,   and   our   current   tower’s   lack   of   rigidity,   we   decided   to   change   the   design   of   the   tower   to   the   one   depicted   below   in   Figure   4   below.      

7/3/2014 COMPRESSION   ACTIVITY:   Using   MDF   blocks,   we   had   to   construct   a   tower   that   was   approximately   6   feet   high,   and   capable   of   fitting   a   toy   animal   inside   without  collapsing  in  on  itself.     INITIAL  PLAN/IDEA:  

Figure 1    

Our initial   idea   was   to   build   it   with   crisscrossing   MDF   blocks   much   like   how   bricks   are   used   in   everyday  construction  for  many  buildings  believing   this  to  be  a  safe  option  due  to  its  widespread  use.    

Figure 2   Figure  4   Figure  3  

Placing the   blocks   in   the   planned   arrangement   proved  difficult  as  it  was  often  knocked  down  with   nothing  to  hold  them  together.  This  meant  that  we   were   not   sticking   right   to   the   plan   as   shown   in   Figure   2   and   3   above   with   there   being   gaps   between   blocks.   This   resulted   in   less   than   wished   stability,   as   there   was   no   real   clear   path   for   any   load   to   be   transferred   to   the   ground,   or   for   the   equivalent  reaction  force  


In order  to  have  stronger  supports  along  the  walls,   we   decided   to   have   two   layers   of   blocks   rather   than   just   the   one   as   depicted   in   Figure   5   below   with  one  side  of  the  tower  open  to  accommodate   the   toy   animal.   This   decision   was   taken   purely   on   the  belief  that  it  would  aid  the  tower  in  distributing   the   load   more   evenly,   thus   allowing   it   to   hold   a   greater  mass.    

Figure 5    

The instability  of  our  revised  design   due  to  the  lack   of  compression  on  the  blocks  became  known  to  us   when   continuing   to   build   the   tower   higher.   A   column   collapsed;   unable   to   hold   the   blocks   above   it  as  shown  below.  

Rather, if  the  initial  design  of  the  tower  was  stuck   to,   and   carried   out   to   reasonable   effect,   it   would   have   been   more   effective   in   holding   a   large   mass.   There   would   have   been   greater   compression   of   blocks  throughout  the  structure  due  to  the  weight   of   the   live   load   pushing   down,   and   with   no   room   for  blocks  to  move,  and  thus  no  weak  points  within   the   tower,   it   would   have   been   able   to   transfer   that   force   straight   into   the   ground.   As   is   shown   below   in   another   group’s   tower   where   even   with   blocks   being   removed,   the   structure   could   still   hold   a   considerable  mass.  

Figure 6  

Figure 8  


The gaps   between   the   blocks   mean   that   there   is   room  for  the  blocks  to  move  when  a  load,  force  or   pressure   of   any   quantity   is   placed   on   them.   The   one   block   moving   causes   blocks   both   above   and   below   to   also   shift,   thus   causing   the   whole   tower   to  collapse.   Lack  of  time  meant  that  we  could  not   make  any  more  changes  to  the  design,  but  instead   had  to  continue  with  what  we  had.    

Having to   also   meet   the   requirements   of   an   arch   that   stretched   across   the   length   of   the   sides,   we   created  a  flat  roof.  The  end  result  being  an  average   sized  tower  with  a  bit  of  the  side  having  collapsed.     However,   when   some   weight,   in   this   case   a   water   bottle   was   placed   on   top   of   it,   the   entire   tower   collapsed.  Being  a  result  of  as  discussed  before,  the   lack   of   compression   and   the   blocks   being   too   far   apart  meant  that  it  allowed  for  them  to  bend  and   thus   compromise   the   integrity   of   the   tower.   With   every  gap  within  the  structure  being  a  weak  point   for   the   force   to   travel   through   to   the   ground,   the   tower   crumbled   when   the   smallest   change   was   made  to  its  overall  load.    


Figure 10  

(Figure 9  &  10  sourced  from  Bow  Vacharussiriyuth)  

Figure 9   Figure  7  



Using a   strip   of   Balsawood   10cm   x   60cm,   to   build   the  tallest  possible  frame  for  a  tower  that  is  stable   and  able  to  support  it  own  weight  (dead  load).    


Cutting it   into   20   individual   pieces,   we   wished   to   build   a   pyramidal   type   structure   with   a   triangular   base,   believing   that   a   thicker   and   stronger   base   would  allow  us  to  create  a  taller  structure.   We  had   originally   planned   on   using   a   glue   gun,   but   due   to   being   unable   to   get   one   in   time,   we   settled   for   masking  tape.      


Figure 1  

CONSTRUCTION:               Figure  2              

The  triangle  base  was  chosen  as  a  triangle  equally   distributes  the  compression  forces  of  the  structure   above   and   as   all   sides   are   of   equal   size,   they   all   have  equal  size,  and  thus  one  is  less  likely  to  buckle   relative  to  one  of  the  others.     Maintaining   the   triangular   shape   throughout   the   frame   of   the   tower   was   aimed   at   ensuring   that   like   the   base,   all   parts   of   the   tower   would   have   the   same  even  distribution  of  load,  and  thus  prevent  it   from   collapsing   under   its   own   weight.   Moreover,   but  slowly  making  each  triangle  smaller,  we  wished   to   angle   the   tower   towards   a   central   point   at   the   top,   ensuring   that   each   level   was   lighter   than   the   level   below   and   thus   making   it   easier   for   the   tower   to  maintain  its  own  weight.            

CHANGE OF  PLAN:                                                                          

Figure 3  

Figure 4  

Despite our   efforts,   the   upper   layers   of   the   tower   were  still  too  heavy,  and  resulted  in  the  bending  of   some   levels   as   shown   in   Figure   4.   Though   due   to   the   extended   base,   the   force   was   still   being   distributed   sufficiently   to   ensure   the   entire   structure  did  not  break,  or  fall  over.       Therefore,   we   chose   to   create   a   truss   of   sorts   within  the  frame  of  the  structure  by  converting  the   parallelograms   into   triangles   with   the   use   of   bracing.   However   due   to   a   shortage   in   sticks,   we   were   unable   to   do   this   to   all   sides   of   the   frame,   thus  us  choosing  to  alternate  the  side  upon  which   to  place  the  bracing  every  level  as  shown  in  Figure   3.               Figure  5    

However this  was  insufficient  still  as  the  dead  load   of   the   tower   was   too   great   for   the   handful   of   braces   that   were   placed   to   make   a   lasting   impact   with   the   top   of   the   tower   still   bending   (Figure   5).   The  lack  of  proper  planning  initially  meant  that  we   were   unable   to   provide   adequate   support   to   the   frame   to   prevent   it   from   buckling.   As   a   result,   we   resorted  to  using  masking  tape  as  a  defacto  brace   as  shown  below.      

Figure 6  


  Figure  7                                         One   of   the   other   groups   who   managed   to   create   the   tallest   tower   in   our   tutorial,   chose   instead   to   create   a   slim   tower   with   regular   bracing.   The   slim   design  minimized  the  horizontal  (lateral)  forces  on   the  structure  making  it  less  likely  to  bend  over.  The   regular   bracing   worked   alongside   the   slim   design   by   creating   a   rigid   frame   that   was   unlikely   to   buckle  as  weak  points  were  minimized.  Though  this   would  make  the  whole  structure  topple  over  if  the   load   was   beyond   what   it   could   hold,   by   extending   the   base   beyond   the   actual   structure,   it   provided   stability  to  the  whole  frame  by  dispersing  the  load   over  a  greater  area.       (Figure  2,  4  &  10  sourced  from  Bow   Vacharussiriyuth)  

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