11

							11. Foundation(Base) rebar arrangement

1) Foundation(base) work
    In foundation work, the lean concrete underneath the footing concrete, is very
   important.
    Without it, constuction site, on which a building will be raised up, it would not be
   clean and stable disturbing construction work.
    Be sure to make lean concrete working mat having at least 50mm of thickness.
    If F.L. of lean concrete is not fit, there are difficulty in fix S.L.


2) The height of spacer
    Bar spacer is used to maintain the arranged bar balanced.
    When arranging the bars or flooring, stones and bricks can not be used to support
   them.
    You have to prepare spacer in advance because there are high possibility of unbalance
   when using stones or bricks to level the ground.
    (in case of spacer height lean concrete top is 60mm)



    < Cover thickness of rebar >

                                              part to not contact land
                                              part to contact land

                                                             over 80mm of cover thickness in
                                                             foundation rebar




                                                                over 50mm of cover thickness than pile
                                                                head on base concrete
lean concrete
      The reason that the top of piles is embedded into foundation is that , in case of an
      earthquake , the pile causes bending fracture.
      Especially , when the ground is unstable , there should be specified directions on
      the drawings.(in case pile cover bending moment & compresssion or cover tension
      properly only)
                                                    6-D13(circular arrangement)



           PC Steel wire




                                                                              2 times of
                                                                              pile diameter
                 Fillup CON’C
                                                    HOOP D13@150 4
                (foundation CON’C)



                        Hole closure                PC or PHC PILE




3) Independent Foundation(Single Footing)
   Usually in double footing and floating foundation , remained bar length is bent up and
  down to splice them together as depicted below.
   However, the remaining parts of the bar can be cut off to reinforce the foundation.

  <In case of securing splice length>       <In case of not securing splice length>


                           when securing                             In case of below
                           splice length                             splice length




                                                                                        standard
                                                                                        hook
4) Foundation(base) pillar tie hoop
    The main purpose of the tie hoop is to restrain the transverse load in order to relieve
  vertical load into pillar.
    Even though foundation concrete has capacity to support the loads from the pillars, tie
  hoops help main bars be fixed at which they should be and it is important job.


            <Before reinforcement>                                 <After reinforcement>

                                                            main bar            tie hoop should be
                               pillar                                           @300 distance per
     slab
                                                                                the drawing regulation,

                                                                   tying


                                           footing
                                                          MAT
                                                                                 bottom tie hoop


                    lean concrete       spacer

                                                                                      pillar


       The tie hoops at the bottom hold the bars of the pillar in lean concrete and marking
       on the mould form is compared with drawing to ascertain the center of the pillars.

                                          <Foundation plate>




                                                 pillar location            marking



                                        eccentric

                               The outer pillar must check main bar line.



5) Foundation(base) upper-support(Wooma) rebar
    - Foundation thickness : below T=1,000mm for HD16, over T=1,000mm for HD19
     space should be @1000-@1500