Clay J. Naito, Ph.D., P.E.
Associate Professor and Associate Chair
Dept. of Civil and Environmental Engineering

Contact Information
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Current Research:

NSF: Development of a Blast and Ballistic Resistant Precast Concrete Armored Wall System

NEES-CR: Impact Forces from Tsunami-Driven Debris

Inspection Methods & Techniques to Determine Non Visible Corrosion of Prestressing Strands in Concrete Bridge Components

Daniel P. Jenny PCI Fellowship: Analytical Assessment of the Resistance of Precast Strucutres to Blast Effects

Development of a Seismic Design Methodology for Precast Diaphragms

Development of a Welding Procedure Specification for Field Welding of Precast Concrete Connections

Use of Polyurea for Blast Hardening of Concrete Construction

Estimation of Concrete Respone Under Varying Confinement

Evaluation of Bond Mechanics in Prestressed Concrete Applications

Horizontal Shear Capacity of Composite Beams Without Ties

Lateral Resistance of Plywood and Oriented Strand Board Sheathing After Accelerated Weathering

Past Research Projects

Performance of Bulb Tees with Self Consolidating Concrete

FRP Bridge Decks with RC Parapets

Blast Resistance of a Load Bearing Shear Wall Building

Lehigh@NEES Equipment Site

Reserarch Experinece for Undergraduates

Seismic Evaluation of a Three Story WoodFrame Apartment Building with Tuck-Under Parking

Design of RC Bridge Beam-Column Connections

Response of Waffle Slab Building Systems to Seismic Loads

Collaborative Research: Development of a Blast and Ballistic Resistant Precast Concrete Armored Wall System

Executive Summary
Terrorist attacks have been carried out on our infrastructure at home and abroad at an alarming rate in the past decade. To protect our facilities and the people who work and reside in them from these threats, blast design criteria have become a standard structural requirement for U.S. government and military buildings. To meet these requirements traditional cast-in-place reinforced concrete construction methods are often utilized. While this type of construction has been proven against blast demands, the high economic cost, long construction timeline, and low energy efficiency makes it a reluctant choice for owners and designers.

Insulated concrete sandwich wall panels have been used successfully in standard building construction for many years. These systems consist of an exterior fašade an insulating foam layer and an interior structural concrete layer. The precast form of construction allows for a rapid construction schedule and is ideal for projects where short timelines are desired. The insulating properties of the panels provide a high thermal resistivity resulting in an energy efficient building with low winter heat loss and low summer cooling requirements. Most importantly these systems provide an effective means of protection against the blast pressures generated from an explosion. The high mass of the concrete wall coupled with the sandwich configuration of the panels provides an elevated resistance to the dynamic effects of blast demands. These characteristics have been demonstrated in recent experimental studies funded by the Portland Cement Association (PCA). Building on these results, the development of an enhanced precast concrete wall system is proposed.

The objective of the proposed research is to develop a multi-threat resistant insulated concrete wall system for high risk facilities. The wall system will be specifically developed to resist blast over pressures, contact detonations, ballistic demands from small arms, mortars and rockets, and the entry resistance requirements for state department facilities. The system will be based on standard precast concrete sandwich wall construction to maintain constructability and thermal efficiency. Enhancements in concrete, reinforcement and integration of textiles will be examined to accomplish the design goal. The modifications will be based on an analytical modeling of the wall system subjected to the various demands. Nonlinear finite element methods will be used to model existing sandwich wall response to blast pressures. These models will be validated with existing experimental data. A parametric study will be conducted to identify effective modifications in constitutive and reinforcement properties for improved ductility and strength. Finite element studies will also be used to examine shockwave propagation to develop improved spall and breach resistance against contact detonations. Ballistic and entry resistance will be addressed by incorporating innovative reinforcement strategies and high strength concretes. The final system will be experimentally validated through static and dynamic tests. These tasks will be accomplished through a collaborative study carried out by researchers at Lehigh and Auburn University.

Research Team
Clay Naito, Professor, Principal Investigator Lehigh University
Jim Davidson, Professor, Co-PI Auburn University
Patrick Trasborg, MS/Ph.D. Graduate Student Researcher
Ernest Maiteri, M.Eng. Student Researcher 2011
John Archibald, REU Student 2011

Publications
1. Naito, C., Hoemann, J., Shull, J., Beacraft, M., Bewick, B., and Hammons, M. "Dynamic Performance of Non-Load Bearing Insulated Concrete Sandwich Panels Subject To External Demands," Air Force Research Laboratory Report, AFRL-RX-TY-TR-2009-XXXX, September 2010, 123 pages.
2. Naito, C., Hoemann, J., Shull, J., Saucier, A., Salim, H., Bewick, B., and Hammons, M. "Static Performance of Non-Load Bearing Insulated Concrete Sandwich Panels Subject To External Demands," Air Force Research Laboratory Report, AFRL-RX-TY-TR-2009-XXXX, July 2010, 164 pages.

Acknowledgements
This material is based upon work supported by the National Science Foundation under Grant No. CMMI-1030812. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Page Last Updated Monday, 15-Aug-2011 10:23:33 EDT