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1. Introduction
The column-foundation connection through socket consists of em-
bedding part of the precast column into the cavity of the foundation
element. This connection is widely used in precast concrete struc-
tures all over the world, being the most widespread in Brazil com-
pared to other available types of column-foundation connections.
This work presents a complementary analysis of the socket foun-
dation initiated in Canha & El Debs [1], in which a critical analysis
of available models and recommendations for socket are present-
ed, and in Canha & El Debs [2], which proposes a design model for
this element. These two abovementioned publications, however,
are focused mainly on friction models for smooth socket founda-
tion. More recently, Campos et al. [3] presented indications for the
structural analysis of the column base in smooth interface sockets.
The present work aims at presenting a complete structural analysis
and detailing approach to precast column-socket connections with
rough interfaces, including a configuration of this type of interface
with shear keys proposed by Canha [4], refined design models
proposed by Campos [5] and recommendations for rough socket
foundation of the latter author. Based on Campos [5], it is easy to
confirm that some questions relative to column-socket connection
with rough interfaces, such as the column base, still remain un-
solved. On the other hand, Canha [4] indicated that smooth socket
model can be applied to the case of rough interfaces by simply ad-
justing the friction coefficient to 1.0. This approach was adopted in
the present work by adapting the model proposed by Campos et al.
[3] to the rough column base. To complement the formulations and
recommendations proposed, a new model is proposed for analysis
and detailing the rough column base based on the monolithic be-
havior of rough connections pointed out by Canha [4]. The results
of two analysis models for column bases are then confronted.
2. Model and recommendations
for the design of rough socket
2.1 Rough interface configuration
A socket foundation connection is defined as rough when shear keys,
responsible by the load transfer between the column and socket, are
executed in the internal socket walls and on the precast column along
the embedment region. Besides the contribution of bond and friction,
183
IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 2
R. M. F. CANHA |
G. M. CAMPOS |
M. K. EL DEBS
Figure 1 – Model for determining the maximum shear strength (Rizkalla et al. [7])
sk
b = shear wall thickness
Friction force
due to shear
Resul ting
normal force
q
c
V '
Force in
strut (2V ')
c
V '
a
V '
c
c
c
a
Pre-load
V
Forces in
struts
V '
c
j
Typical
strut
sk
V
h
Surface
slip
cos
Appl ied normal force
V
sk
q
j
cos
sk
h
j
h
sk
q
h
sk