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Geotechnical News • June 2012
March 2012
THESIS ABSTRACTS
Three-Dimensional Nonlinear Analysis of
Deep-Corrugated Steel Culverts
Tamer Elshimi
Tamer Elshimi, Thurber Engineering Ltd., 200, 9636-51 Avenue
NW, Edmonton, AB T6E 6A5, T: 780-438-1460,
Deep-corrugated steel culverts (with a corrugation wave-
length of 400mm and amplitude of 150mm) can be used
as an effective alternative for short-span bridges. Current
design methods are typically based on two-dimensional
finite element analysis. This thesis reports results from
three-dimensional finite element analysis, with explicit
modelling of the geometry of the corrugated plates (called
corrugated analyses) and employing the orthotropic shell
theory (called orthotropic analyses), for a specific box
culvert having a 10 m span and 2.4 m rise. The results were
compared to previously reported experimental data where a
specific large span box culvert was tested under controlled
laboratory conditions. The box culvert was modelled when
subject to fully loaded dump truck, and when loaded using
a tandem axle frame to service and ultimate loads. It was
found that the orthotropic model overestimated the culvert
stiffness at the ultimate limit state, but provided effective
estimates of response up to the factored design loads. The
corrugated model with geometric nonlinearity was required
to capture the real behaviour of the corrugated plates up to
the ultimate limit state. New insight into the failure mecha-
nisms of the box culvert were provided by the corrugated
model analysis. A parametric study was then performed for
86 different long-span box and arch culverts, examining
live load spreading in the axial direction, number of loaded
lanes, design truck position, culvert geometry, plate thick-
ness, and the existence of pavement. The results were then
compared to the moment and thrust equations in the 2006
Canadian Highway Bridge Design Code (CHBDC) to check
the performance of the current design equations. CHBDC
equations overestimated the earth and live load bending
moments, and did not give the correct trend for different
spans. CHBDC thrust equations were found to underesti-
mate the earth and live load thrust values for arch culverts.
Sponsor: Ian D. Moore, Ph.D., FCAE, FEIC, Professor and Canada
Research Chair, and Richard Brachman, Ph. D., Associate Profes-
sor, Department of Civil Engineering, Ellis Hall, Queen’s Univer-
sity, Kingston, ON., K7L 3N6
Effects of Loading – Unloading and Wetting –
Drying Cycles on the Geomechanical
Behavior of the Colombian Andes Mudrocks
Mario Camilo Torres Suárez
Mario Camilo Torres Suárez, Calle 44 No. 8-11 Apartment 202,
Edificio Torres de la Javeriana, Bogota D.C., Colombia
T: 571-3165000 Ext 13309,
F 571-3165459, E:
;
The Colombian Andes mudrocks, particularly those that
exhibit low grade of cementation (bonding), are very much
susceptible to degrade when the environmental conditions
change, representing a lot of problems for the engineering
works. This research develops environmental conditions
simulated by lab techniques in order to monitoring physics
and mechanical properties changes, whit these actions and
to establish some real effects on the material mechanical
competence. For the research aim, were developed activities
as geotechnical characterization, from physics – chemical
– mechanical and compositional points of view, and their
respective experimental design and lab sets, implementing
recent techniques as Vapor Equilibrium (VET) in order to
apply wetting – drying cycles, controlling relative humid-
ity (controlled suction), and loading – unloading cycles
during the triaxial tests, trough ultrasonic wave velocities
technique; this was possible due to coupled transducers
to the compression machine (Hoek cell), determining also
the stress – strain behavior front these actions. The most
relevant results are, between others: the principal failure
mechanisms for the laminated mudrocks starts on the micro-
scopic scale by fissures coalescence, exhibiting as well as
physics and chemical degradation phenomenon; the strength
is reduced up 100% and 60% and rigidity is reduced up 70%
and 30%, for three wetting – drying and loading – unloading
cycles, respectively; the global geomechanical behavior to
get across between a ductile like rock to a fragile like soil,
but obtaining engineering values according the monitoring
lab set, compared with the in-situ conditions.
Sponsor: Dr. Adolfo Alarcón Guzmán, National University of
Colombia, Engineering Faculty, Civil y Agriculture Engineering
Department, E:
