Latin American and Caribbean Consortium of Engineering Institutions
Conference Track: Engineering
& Public Service
Keywords:
Centrally Prestressed Unreinforced Concrete Column; pile; inelastic
analysis; hinge
Contact Title:
Dr.
Contact First Name: D. V.
Contact Last Name: Reddy
University:
Florida Atlantic University
Web: http://www.civil.fau.edu/faculty_staff.htm
Position:
Professor of Civil and Ocean Engineering
Country:
USA
Email:
dvreddy@oe.fau.edu
Paper Title:
Centrally Prestressed Concrete Members in Compression and Bending
Abstract:
It has been observed that the compressive resistance of axially
loaded reinforced concrete components is invariably less than the sum of
individual strengths of the constituent concrete and steel elements due to
structural incompatibility in the inelastic phase. Structural instability,
at or near ultimate limit states in traditionally reinforced concrete
columns, renders accurate prediction of their resistance to be difficult.
This unreliability, exacerbated by the fact that loading of columns
without eccentricity is practically impossible, causes design codes to
specify severe resistance factors in order to assure a desirable safety
level. Structural reliability is further impaired by the probability of
spalling of the concrete cover due to corrosion of the reinforcement.
A series of tests were carried out in which the performance of the
"Centrally Prestressed Unreinforced Concrete" (CPUC) column was
compared with that of traditionally constructed bridge piers and piles.
The CPUC column design is an innovative idea, by which the innate
incompatibility between concrete and steel is eliminated by removal of the
latter; but flexural resistance and ductility are restored by the
application of a centrally located prestressing tendon or closely spaced
strands. This concentration of steel results in a significant increase in
concrete cover for better corrosion protection without loss in strength.
The practical applicability of the CPUC column design concept is
substantiated by an inelastic analysis. CPUC column test results are
compared with those for traditional reinforced concrete and prestressed
concrete columns.
Columns fitted out with modified Freyssinet hinges, with which the
central prestressing tendon is structurally compatible, allow a control,
especially for earthquakes, for the eccentricity of axial forces. The
second phase deals with an energy absorbing device compatible with the
CPUC column to meet the occasional high ductility demand of the CPUC
columns in earthquake conditions. Hinges were tested for compressive
strength and moment-rotation capability. Parametric studies of the hinges
were conducted for different filler materials, and width-to-height ratios.
The confined filler material in the Freyssinet type hinge was found to
have excellent compressive strength and moment-rotation capability. The
parameters, width-to-height ratios and different filler materials, had
significant effect on the hinge's performance.
Mailing Address:
Department of Civil Engineering
Bldg. 36, Rm. 216
Florida Atlantic University
777 Glades Road, Boca Raton, FL 33431
Phone:
1 (561) 297 - 3443
Authors:
Dr. D. V. Reddy
dvreddy@oe.fau.edu
Professor of Civil and Ocean Engineering
Department of Civil Engineering
Bldg. 36, Rm. 216
Florida Atlantic University
777 Glades Road, Boca Raton, FL 33431