the ends of two vertical reinforcing bars. The hairpins are  then  placed  in  the  end  of  the  panel  before  the concrete  is  poured.  These  lifting  attachments  must protrude from the top of the form for attaching the lifting  chains  or  cables,  but  go  deep  enough  in  the panel form so they won’t pull out. Among   the   commercial   types   of   lifting attachments, you will find many styles with greater lifting  capacities  that  are  more  dependable  than hairpins  if  properly  installed.  These  are  used  with lifting plates. For proper placement of lifting inserts, refer to the plans or specs. Spreader Bars Spreader  bars  (shown  in  figure  6-9)  may  be permanent or adjustable, but must be designed and made according to the heaviest load they will carry plus a safety factor.    They are used to distribute the lifting  stresses  evenly,  reduce  the  lateral  force  applied by slings, and reduce the tendency of panels to bow. POINT  PICKUP  METHODS Once  the  concrete  has  reached  the  desired strength,  the  panels  are  ready  to  be  lifted.  The strength of the inserts is governed by the strength of the  concrete. CAUTION An early lift may result in cracking the panel,  pulling  out  the  insert,  or  total  concrete failure.  The  time  taken  to  wait  until  the concrete has reached its full strength prevents problems and minimizes the risk of injury. There are several different pickup methods. The following  are  just  some  of  the  basics.  Before  using these  methods  on  a  job,  make  sure  that  you  check plans  and  specs  to  see  if  these  are  stated  there. Figure 6-11 shows four different pickup methods: 2, 2-2, 4-4, and 2-2-2. The  2-point  pickup  is  the  simplest  method, particularly for smaller panels. The pickup cables or chains are fastened directly from the crane hook or spreader bar to two pickup points on or near the top of the  precast  panel. The 2-2 point pickup is a better method and is more  commonly  used.  Variations  of  the  2-2  are  4-4 and  2-2-2,  or  combinations  of  pickup  points  as designated  in  the  job  site  specifications.  These methods  use  a  combination  of  spreader  bars,  sheaves, and  equal-length  cables. The  main  purpose  is  to distribute  the  lifting  stresses  throughout  the  panel during erection. Remember, the cables must be long enough to allow ample clearance between the top of the panel and the sheaves or spreader bar. ERECTING, BRACING, AND JOINTING PANELS Erecting is an important step in the construction phase of the project. Before you start the erecting phase  and  for  increased  safety,  you  should  make  sure that  all  your  tools,  equipment,  and  braces  are  in proper working order. All  personnel  must  be  well informed  and  the  signalman  and  crane  operator understand  and  agree  on  the  signals  to  be  used. During the erection of the panels, make sure that the signalman and line handler are not under the panel and that all unnecessary personnel and equipment are away  from  the  lifting  area.  After  the  erection  is  done, make  sure  that  all  panels  are  properly  braced  and secured  before  unhooking  the  lifting  cables. Bracing is an especially important step. After all the work of casting and placing the panels, you want them to stay in place. The following are some steps to take  before  lifting  the  panels: Install the brace inserts into the panels during casting  if  possible. Install  the  brace  inserts  into  the  floor  slab either   during   pouring   or   the   day   before erection. Install  solid  brace  anchors  before  the  day  of erection. If brace anchors must be set during erection, use a method that is fast and accurate. Although there are several types of bracing, pipe or  tubular  braces  are  the  most  common.  They  usually have  a  turnbuckle  welded  between  sections  for adjustment. Some  braces  are  also  made  with telescoping   sleeves   for   greater   adaptability. Figure 6-10 shows tube-type braces used to hold up panels.  Cable  braces  are  normally  used  for  temporary bracing and for very tall panels. Their flexibility and tendency to stretch, however, make them unsuitable for  most  projects. Wood  bracing  is  seldom  used except  for  low,  small  panels  or  for  temporary  bracing, Jointing  the  panels  is  simple.  Just  tie  all  the panels  together,  covering  the  gap  between  them.  You can  weld,  bolt,  or  pour  concrete  columns  or  beams. Steps used to tie the panels should be stated in the plans and specs. 6-21