Development of finite elements for computational solid, structural and fluid mechanics, with an emphasis on nonlinear problems.

Design and analysis of integration algorithms in time for computational solid, structural and fluid mechanics.

Development of efficient staggered methods for coupled problems.

Formulation, analysis and numerical implementation of constitutive models in solid mechanics (e.g. finite strain thermoplasticity).

In particular, analysis and numerical simulation of localization in solids, including shear banding in metals and cracking in concrete.

Fundamental nonlinear continuum mechanics.

General numerical analysis with a direct application to computational mechanics (e.g. equation solvers for stiff systems).

Behavior and design of steel column base plates subjected to monotonic and cyclic loading.

Development of new design procedures for single member and multi-member steel gusset plates.

Investigation of inelastic behavior and developing models of behavior of simple, semi-rigid, and rigid steel structures and connections.

Seismic studies of the Bay Bridge.

Seismic behavior and design of steel shear connections with slab effects.

Behavior and seismic design of composite shear walls.

Remote data collection and study of seismic behavior of steel structures.

Topics in earthquake analysis and response of multistory buildings, including accidental and natural torsion, evaluation of building codes, dynamic analysis procedures for performance-based design of buildings, and interpretation of motions recorded during earthquakes.

Topics in earthquake analysis and design of concrete dams, including dam-fluid interaction, dam-foundation rock interaction, and spatial variations in ground motion.

The development of macroscopic constitutive models for a wide variety of materials using information about their molecular structure, the use of such models in large scale nonlinear finite element calculations, and related issues. Applications include:

Phenomenological modeling of the failure of concrete due to microcracking for application in large scale inelastic finite element calculations.

Inverse motion problems in elasticity and plasticity.

Simulation of lithographic etching.

Various topics in theoretical and computational solid mechanics, constitutive theory, and micromechanics.

Development and testing of aseismic base isolation systems. These systems incorporate elastomeric multi-layer bearings of various types. The research is both analytical and experimental in nature, with most of the experimental work conducted on the 20 ft. by 20 ft. shaking table at the Earthquake Simulator Laboratory.

Constitutive theory for large cyclic plastic deformation of shape memory alloys. This research is concerned with developing better material models for energy-absorbing devices of this material.

Development of energy-absorbing devices for seismic-resistant structures. Devices under study include viscoelastic materials, frictional components, or metallic elements.

Computational Continuum Mechanics: 

1. Constitutive modeling; (numerical simulations of shear band formation/propagation, fracture/crack propagation, damage evolution, ductile-to-brittle transition at small scale)

2. Multi-scale methods; (developing numerical cohesive models, computational methods in gradient elasticity and gradient inelasticity, wavelet/multi-scale decomposition techniques) 

3. Meshfree/Particle methods and their applications;

Active Material/Structure Modeling:

1. Electro-acoustic wave propagation in piezoelectric/dielectric media;

2. Dynamic fracture in ferroelectric (piezoelectric) materials;

3. Crack and dislocation interactions in piezoelectric media;

Micromechanics Modeling of Civil Engineering Structures:

1. Micromechanics of linear/nonlinear shell theory;

2. Inclusion theory and cell models

Basic studies on the seismic behavior and design of structural systems for bridges or buildings and executed in steel, reinforced concrete or wood focused on: (a) performance enhancement through use of energy dissipation devices and seismic isolation; (b) effect of configuration of moment and braced frames, coupled walls, and other systems, and the hysteretic characteristics of their structural elements on performance; (c) effects of designer decisions related to proportioning and structural idealization on the performance of the as-built structure; (d) effect of special ground motion conditions (near-fault, soft-soil motions, multi-directional excitation) on structural performance; and (e) development of damage-tolerant structural systems.

Analytical and experimental investigations of: (a) bridges; (b) reinforced concrete buildings; (c) steel buildings; and (d) wood buildings.

Development of advanced experimental procedures such as on-line computer controlled seismic simulation, concurrent testing at distributed experimental facilities, innovative field testing methods, data archival, etc.

Methodologies for optimal, computer-assisted, reliability-based design of structures.

Policy and economic issues related to seismic performance of structures and urban environments.

Analytical and experimental studies of the behavior of reinforced and prestressed concrete elements and structures.

Post-earthquake evaluation of RC buildings and bridges.

Design parameter studies of buildings and bridges.

Evaluation, rehabilitation, and repair of existing structures.

Performance-based earthquake engineering.

Development of high performance concretes.

Mass concrete for dams and nuclear power plants.

Durability of concrete corrosion, sulfate attack, ASR.

Non-destructive methods.

Fracture and damage mechanics of concrete structures.

Seismic evaluation and rehabilitation of existing structures.