Civil Engineering

Professor of Civil Engineering, CWRU

105A Bingham Building

216.368.2427

axs31@case.edu

http://vorlon.case.edu/~axs31/

1. Elasticity
2. Statics and Dynamics of Soils and Foundations
3. Soil Instabilities - Shear Banding and Liquefaction

• Ecole Centrale de Paris, Ingenieur, 1958
• University of Grenoble, Eq. Msc. 1959
• Princeton University, Ph.D. 1961

Teaching Interests - For more than forty years Professor Saada has taught classes on analysis and design in nearly all the undergraduate areas of Civil Engineering. He also teaches graduate courses in Mechanics of Continuous and Particulate Media, Elasticity Theory and Foundations Engineering. He is the author of a textbook on Elasticity Theory and its Applications, now in its 2nd revised and updated edition (2009).

Research Interests - Dr. Saada’s research has been supported by the National Science Foundation for over thirty years without interruption. In addition, support from the Army Research Office, the Air Force Office of Scientific Research and the Corps of Engineers added breath to the investigations conducted at Case. The research impacted a broad range of topics in the area of geomaterials. In 2000 Dr. Saada established the Saada Family Fellowship to support graduate students in Civil Engineering. The Saada Charitable fund has contributed over $500,000 towards the support of 8 doctoral candidates in three disciplines of civil engineering.

Dr. Saada and Saada Family Fellows

Example Research: Strength Testing of Soils

While the profession had long known that soils were cross anisotropic, no techniques existed to rotate the principal stresses to study the influence of anisotropy on soil strength. Cutting inclined soil specimens is unacceptable because of end effects. The most convincing illustration of these was provided by Dr. Saada in 1970 when he published a series of photographs showing the bending and shearing of specimens during compression testing. Dr. Saada then designed equipment to make hollow cylinder test specimens and the cells in which they are tested. He also established the proportions for improved testing, which are still used.

Example Research Project: Impact on the Driving Systems Used in Soils Testing

Dr. Saada developed the first system to apply simultaneously axial, torsional and spherical effects on soils. A pneumatic analog computer called SPAC was used to conduct hundred of tests on sands and clays. These same basic procedures are used today, but with the advent of microcomputers, many Universities (including CWRU) have converted from fluidics to electronics control systems.

Example Research: Impact on Constitutive Models

Dr. Saada published the first constitutive model for anisotropic clays based on experiments in his SPAC torsional shear hollow cylinder device. This led to many models claiming better capabilities. Dr. Saada then headed a 4-year program with the Univ. of Grenoble to evaluate models. He and coworkers performed hundreds of tests and evaluated over 30 models during an International workshop funded by NSF, the U.S. Army, the Bureau of Reclamation and the French government. This set validity ranges for models and identified their advantages and limitations. The workshop proceedings appeared in a distinguished volume which has been hailed as “The Reference” on constitutive equations.

Example Research: Liquefaction Using the Unit Energy Concept.

Drs. Figueroa and Saada developed and tested an approach based on Energy to determine the liquefaction potential of soil deposits. As a member of the team studying the Northridge Earthquake they obtained initial verification of its validity using both hollow cylinders and a medium-size centrifuge.

Example Research: Improving Soils Mechanics

The application of fracture mechanics and thermodynamics in the solutions of stability for stiff clays was introduced by Dr. Saada and Dr.Chudnovsky, in the eighties. Dr. Saada continues his interest in this area.

Example Research: Geotechnical Test Data

Dr. Saada and Dr. Bianchini developed a Geotechnical Test Data Base available to researchers to gauge the performance of constitutive equations. The Data Base contains results from 260 tests conducted on cubes and hollow cylinders. It has been distributed to over 40 research institutions around the world. It can be downloaded from the Department’s web page: http://ecivwww.cwru.edu/civil/

Example Research: Bifurcation and Shear Banding in Saturated Cohesive Geomaterials

Discontinuities such as cracks or fissures and inclusions are often present in clays. They serve as stress concentrators when loads are applied. Such concentrations result in cracking, often surrounded by a propagating damage zone. As cracks propagate, damage may be in one or more shear bands, which may act as new stress concentrators and blunt the action of the original crack. A report to the Air Force was the first to show the initiation of shear bands and their propagation in normally and over consolidated clay. Results were published in Geotechnique in a paper that was awarded the Telford Prize. The measuring techniques developed are now used by investigators studying the kinematics of granular media.

Example Research: Bifurcation and Shear Banding in Non-Cohesive Geomaterials

In sands, digital image processing techniques were developed and used to observe the displacements and the development and propagation of the shear bands. Such bands are distributed along the specimens and upon bifurcation, some coalesce and result in a major band. The inclination of the bands for three sands of difference granulometry was found to follow the Arthur-Vardoulakis criterion. Relative density and confining pressures were found to have little or no effects on this inclination. Shear and normal strain measurements were made within the shear band which was found to change in size with particles moving in and out of it. This study is the first of its kind and was published in Geotechnique.

“The Development of a Data Base Using the Case Hollow Cylinder Apparatus,” Proc.Int.Workshop on Constitutive Equations for Granular Non-Cohesive Soils, 1987 (w/Puccini),Edited by A. Saada and G. Bianchini.

“Micromechanisms of Deformation in Fracture of Over consolidated Clays,” Canadian Geotech. J 25(2),213-221, 1988 (w/Chudnovsky & Lesser).

“Validation of Failure Models of Granular Soils,” Proc., 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, August 1989.

“Comportement Tri-dimensionnel des Sables: Comparaison d’Essais Veritablement Triaxiaux et d’Essais sur Cylindres Creux”. Revue Francaise de Geotechnique No. 49, Oct. 1989.

“Complex Stress Paths and Validation of Constitutive Models”, Geotech. Testing J. GTJODJ, 14(1), 13-25, 1991 (w/Bianchini).

“The Mechanical Properties of Anisotropic Granular Soils”, in Failure Criteria in Structured Media, J.P. Boehler, 1993 Balkema, 453-462. (w/Bianchini &Puccini).

“Cracks, Bifurcation and Shear Bands Propagation in Saturated Clay”, Geotechnique, 44(1), 35-64, 1994 (w/Bianchini & Liang). This paper was awarded the Telford Prize.

“Fracture Mechanics and Plasticity in Saturated Clay,” ASCE, Proc. on the Application of Fracture Mechanics to Geotechnical Eng., ASCE Geotechnical Special Pub. No. 43, 1994.

“Effect of the Grain Size on the Energy per Unit Volume at the Onset of Liquefaction.” Proc. Third Int. Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, 1995,(w/Figueroa & Liang).

“Liquefaction Under Random Loading: A Unit Energy Approach,” J. Geotech. Eng. Div. ASCE, 121(11) 776-781, 1995 (w/Liang and Figueroa).

“Shear Strength and Shear Modulus Degradation Models Based on the Dissipated Unit Energy,” Proc., XIVth Int. Conf. of Soil Mechanics and Foundation Engineering, Hamburg, Germany, 1997 (w/Figueroa, Kern & Lang).

“The Use of Digital Processing in Monitoring Shear Band Development,” ASTM Geotech. Testing J., 20(3), 1997(w/Liang, Figueroa & Cope).

“Bifurcation and Shear Band Propagation in Sands”,Geotechnique,49(3),367-385,1999(W/Liang,Fiqueroa & Cope)

“Validation of the Energy-Based Method for Evaluating Soil Liquefaction in Centrifuge,” Proc., 4th Int. Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, 2001. (w/Dief & Figueroa).

“Field Verification of the Energy-based Procedure to Predict the Liquefaction Potential of Soil Deposits,” Proc., 5th Int. Conference on Case Histories in Geotechnical Engineering, 2004 (w/Tao & Figueroa).

“Influence of Non-Plastic Fines Content on the Liquefaction Resistance of Soils in Terms of the Unit Energy,” Proc., Int. Conference on Cyclic Behavior of Soils and Liquefaction Phenomena, 2004, Balkema. (w/Tao & Figueroa)

“Elasticity, Theory and Applications,”2nd Edition, Revised and updated (pp 850),J. Ross Publishing, Inc. Fort Lauderdale, FL., 2009