Socket Connection between Precast Column and Precast Foundation Completed by Corrugated Metal Pipe (CMP) and Grout

Surface of embedded column shall be clean, free of laitance with exposed aggregate finish. Formwork retarder is recommended to complete the exposed aggregate surface.

Precast column shall be embedded into preformed socket no less than 1.0D, where D is the column diameter. The shear stress at column surface due to the gravity loads, Vc, shall be no greater than 0.5 ksi, in which: V_c=P/(πD_c L_e )       where
      P = gravity load at column base (kip)
      D_c = column diameter (in.)
      L_e = column embedment length (in.)

The shear stress at pipe surface due to the gravity loads, Vp, shall be no greater than 0.4 ksi, in which: V_p=P/(πD_p L_e )       where
      P = gravity load at column base (kip)
      D_p = column diameter (in.)
      L_e = column embedment length (in.)

• Base Metal and Surface
Base metal composition and coating for corrugated steel pipe (CSP) shall meet the requirements of AASHTO M218.
Surface of CSP shall be clean, free of grease and laitance on both sides.
• Corrugation Pattern
Corrugated steel pipe (CSP) shall be with annular (circumferential) seams. The corrugations shall be 2-2/3” by 1/2" for pipe with diameter no larger than 84”.
• Thickness
Corrugated steel pipe (CSP) shall provide the same circumferential hoop force in the joint as that required by transverse reinforcement of Article 8.13.3 of the 2009 LRFD SGS. • Early Strength (1 day compressive strength) and Strength (28 days compressive strength)
Grout with early strength (1 day compressive strength) no less than 4000 psi is prefer to achieve a faster construction speed.
28 days compressive strength of the grout shall be no less than 8000 psi.
Compressive strength shall be determined as the requirements of ASTM C109, using 2 in. cube specimens.
• Flowability and Working Time
Flowability and working time are various based on grout type and environmental conditions. Trail batch is strongly recommended in construction site to ensure the grout can properly fill the spacing in socket.
• Shrinkage
Grout shall meet the requirements of ASTM C1107, thereby qualifying as a Non-shrink grout.