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Displaying 1 - 25 of 64

Energy-Based Design Approach for Seismic Design: Energy Spectra

October 12, 2021
Author(s)
P Khashaee, B Mohraz, Fahim H. Sadek, Hai S. Lew, John L. Gross
Among the approaches that the Structural Engineers Association of California has recommended for performance based seismic design is the energy approach. In this approach, the earthquake input energy transmitted to the structure is estimated from ground

Structural Performance of Nuclear Power Plant Concrete Structures Affected by Alkali-Silica Reaction (ASR) - Task 1: Assessing In-Situ Mechanical Properties of ASR-Affected Concrete

February 8, 2021
Author(s)
Fahim H. Sadek, Travis E. Thonstad, Sorin Marcu, Jonathan Weigand, timothy J. barrett, Hai S. Lew, Long Phan, Adam L. Pintar
This report describes the results of Task 1 of a five-task comprehensive research program being conducted at the National Institute of Standards and Technology (NIST) under the sponsorship of the U.S. Nuclear Regulatory Commission (NRC). The overall study

Structural Performance of Nuclear Power Plant Concrete Structures Affected by Alkali-Silica Reaction (ASR) - Task 2: Assessing Bond and Anchorage of Reinforcing Bars in ASR-Affected Concrete

February 3, 2021
Author(s)
Travis E. Thonstad, Jonathan Weigand, Fahim H. Sadek, Sorin Marcu, timothy J. barrett, Hai S. Lew, Long Phan, Adam L. Pintar
This report describes the results of Task 2 of a five-task comprehensive research program being conducted at the National Institute of Standards and Technology (NIST) under the sponsorship of the U.S. Nuclear Regulatory Commission (NRC). The overall study

New Connections for Enhancing Robustness of Precast Concrete Frame Structures

February 24, 2018
Author(s)
Travis E. Thonstad, Yihai Bao, Jonathan M. Weigand, Joseph A. Main, Hai S. Lew
A recent experimental and computational study of two precast concrete moment-frame assemblies under a column removal scenario revealed vulnerabilities in the moment connections arising from (a) local bending of reinforcing bars due eccentricity in the

An experimental study of precast concrete moment frames under a column removal scenario

September 1, 2017
Author(s)
Hai S. Lew, Joseph A. Main, Yihai Bao, Fahim Sadek, Vincent P. Chiarito, Stephen D. Robert, Jorge Torres
This paper presents a full-scale experimental study of two precast concrete moment-frame assemblies, each comprising three columns and two beams. The assemblies represented portions of seismically designed perimeter moment frames from two 10-story

A SIMPLE METHOD OF ENHANCING THE ROBUSTNESS OF R/C FRAME STRUCTURES

June 1, 2016
Author(s)
Yihai Bao, Hai S. Lew, Fahim Sadek, Joseph A. Main
A simple debonding technique is proposed to reduce or eliminate strain localization in reinforcing bars in the region of wide flexural cracks in RC beams to enhance the resistance of RC buildings to disproportionate collapse (also referred to as

EXPERIMENTAL STUDY OF RC ASSEMBLIES UNDER A COLUMN REMOVAL SCENARIO

July 1, 2014
Author(s)
Hai S. Lew, Yihai Bao, Santiago Pujol, Mete Sozen
This paper presents an experimental study of two full-scale reinforced concrete (R/C) beam-column assemblies under a column removal scenario. The assemblies represent portions of the exterior moment-resisting frames of two ten-story R/C frame buildings

Robustness Assessment of RC Frame Buildings under Column Loss Scenarios

April 3, 2014
Author(s)
Yihai Bao, Joseph A. Main, Hai S. Lew, Fahim Sadek
A computational assessment of the robustness of reinforced concrete (RC) building structures under column loss scenarios is presented. A reduced-order modeling approach is presented for three-dimensional RC framing systems, including the floor slab, and

Robustness of Precast Concrete Frames: Experimental and Computational Studies

April 3, 2014
Author(s)
Joseph A. Main, Yihai Bao, Hai S. Lew, Fahim Sadek
This paper describes both full-scale testing and detailed finite-element modeling of a precast concrete moment-frame assembly extracted from the perimeter moment frame of a 10-story prototype building. The assembly comprises two beam spans and three

A Simple Means for Reducing the Risk of Progressive Collapse

December 1, 2013
Author(s)
Yihai Bao, Hai S. Lew, Fahim H. Sadek, Joseph Main
A simple debonding technique is proposed to reduce or eliminate strain localization in reinforcing bars in the region of wide flexural cracks in RC beams, and as a result enhance the resistance of RC buildings to disproportionate collapse. In this study

Modeling of Reinforced Concrete Assemblies under a Column Removal Scenario

November 8, 2012
Author(s)
Yihai Bao, Hai S. Lew, Sashi K. Kunnath
This paper presents a computational investigation of two reinforced concrete beam-column assemblies, each comprising three columns and two beams, subjected to monotonically increasing vertical displacement of the unsupported center column simulating a

Performance of Steel Moment Connections under a Column Removal Scenario. I: Experiments

April 3, 2012
Author(s)
Hai S. Lew, Joseph A. Main, Stephen D. Robert, Fahim Sadek, Vincent Chiarito
This paper presents an experimental study of two full-scale steel beam-column assemblies, each comprising three columns and two beams, to (1) define their response characteristics under a column removal scenario, including the capacity of the beams and

Performance of Steel Moment Connections under a Column Removal Scenario. II: Analysis

April 3, 2012
Author(s)
Fahim H. Sadek, Joseph Main, Hai S. Lew, Sherif El-Tawil
This paper presents a computational investigation of the response of steel beam-column assemblies with moment connections under monotonic loading conditions simulating a column removal scenario. Two beam-column assemblies are analyzed, which incorporate (1

Modeling and Analysis of Disproportionate Collapse of RC Structures

October 31, 2011
Author(s)
Yihai Bao, Hai S. Lew, S K. Kunnath
Collapse analyses of a 10-story reinforced concrete frame building are carried out to investigate the robustness of structural systems against column removal scenarios. Computationally efficient reduced models are developed and used in the analyses. The