• Precast concrete shell with SCC core
• Precast footing

• Corrugated galvanized ducts are placed in precast foundation, and the duct spiral that is similar to the column in terms of bars size and spacing is installed before placing the top layer of foundation reinforcement
• Column longitudinal reinforcing bars are extended, and inserted into the ducts.
• UHPC is then filled into the ducts to connect column and foundation.
• Column is initially hollow section but after erecting and installing, it is filled with self-consolidating concrete.
• Longitudinal bars are debonded by two wraps of duct type at column-foundation interface.

• validated by experimental test

• Recommended design equation for development length (Ld) of the deformed bars in the UHPC-filled ducts are as follows:
L_d= max(L_d,duct,L_d,bar ) L_d,duct= d_b².f_s/27d_d.√f'_c L_d,bar= d_b.f_s120√f'_UHPC

Where Ld,duct(in) is duct development length based on UHPC-filled duct system, Ld,b (in) is bar development length in the UHPC block, db is bar diameter (in), dd is duct diameter (in), fs is bar stress (psi) that is recommended to be 1.5fy or fu whichever is greater, f’c is compressive strength of normal concrete surrounding the dust (psi) and f’UHPC is compressive strength of UHPC in the duct (psi).

ADVANTAGES	CHALLENGE
• UHPC-fill allow the use of typically foundation with short thickness by reducing reinforcing bar embedment length.	• Construction can be a potential issue because of the difficulty of placing ducts and reinforcing bars with small tolerances.

Structural performance	5/5 (0 have significant issue, 5 same/better when compared to conventional CIP method)
Constructability	3/5 (0 difficult, 5 easily)
Speed of construction	3/5 (0 very slow, 5 very fast)
Cost	5/5 (0 very expensive, 5 cost effective when compared to conventional CIP method)

Organization	Contact name	Phone number	E-mail
University of Nevada, Reno	Mostafa Tazarv M. SaiidSaiidi		saiidi@unr.edu