????????????????? ?????????????????? ????????????????? (Overhaul) ??????????????? ????????????????????????????????????? ?????????????????????????????????? ??????????????????????????????????????????????? ??????????? ?????????????????????????????????????????????????? ????????????????????????????????????????? ????????????????????????????????
ข้อควรระวังงานก่อสร้างด้วยระบบพรีคาสท์คอนกรีต
?????????????????????????????????????????????????? (Precast) ???? ?????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????????????????
สปริงดึง คืออะไร
???????? (Extension Springs) ??? ???????????????????????????????? ??????????? 2 ??????????????????????????????????????? ???????????????????????????? ???????? ?????????????????????????????????? ??????????????????????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????????????