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Arlington, TX, United States

Trautner C.,Simpson Gumpertz and Heger | McGinnis M.,University of Texas at Tyler | Pessiki S.,Lehigh University
ACI Materials Journal | Year: 2011

The incremental core-drilling method (ICDM) is a nondestructive technique to assess in-situ stresses in concrete. These stresses may be constant or vary through the thickness of the concrete member under investigation. In this method, a core is drilled into a concrete structure in discrete increments. The displacements that occur locally around the perimeter of the core at each increment are measured and related to the in-situ stresses. This paper presents results from experimental tests in which simple concrete beams were subjected to controlled loads and in-situ stresses measured via ICDM were compared to known stress distributions. Copyright © 2011, American Concrete Institute. All rights reserved. Source


Phelps A.F.,Simpson Gumpertz and Heger | Horman M.J.,Pennsylvania State University
Journal of Construction Engineering and Management | Year: 2010

Traditional construction research methods have enabled focused but narrow advances in our understanding of industry phenomena. While contributing new insight, these methods are often not adequate to enable understanding of the complex interactions that lead to many of the industry's pervasive social and technical problems. One means of addressing these limitations is for the construction research community to complement prevalent quantitative and case study methodologies with qualitative theory-building methodologies, specifically ethnographic studies or those based on detailed and long-term observation of project environments. This paper identifies the critical need for theory-building methods and their methodological conventions, challenges, and opportunities. Specifically, the paper focuses on data collection in ethnographic studies and analysis of that data through the use of grounded theory. Through better understanding and more widespread use of theory-building methods, the construction research community can provide a needed complement to the current prevailing methods and greatly aid the maturation of our important field. © 2010 ASCE. Source


Hamburger R.O.,Simpson Gumpertz and Heger
AEI 2011: Building Integrated Solutions - Proceedings of the AEI 2011 Conference | Year: 2011

In 2001, the Applied Technology Council (ATC) initiated the ATC-58 Project under contract to the Federal Emergency Management Agency (FEMA). Under this project, ATC is developing next-generation performance-based seismic design criteria for new and existing buildings that will be published as FEMA P-58. Unlike present-generation performance-based design criteria, which characterize structural and nonstructural performance in terms of standardized damage states, the P-58 criteria characterize structural performance in terms of the consequences of earthquake damage including: casualties; repair and reconstruction costs, expressed both in monetary and energy/carbon expenditures; and occupancy interruption time. The performance of nonstructural building components including architectural, electrical and mechanical components and systems is integrally considered with that of the structure. Following a methodology originally developed by the Pacific Earthquake Engineering Research Center, the P-58 procedures revolve around a building performance model that includes fragility and consequence functions for each of the damageable components and systems of significance. Monte Carlo simulation procedures are used to assess potential losses for: individual earthquake shaking intensities; scenario earthquake events, considering uncertainty in ground motion intensity; and, over a period of time, considering uncertainty in the magnitude and distances of scenario events that will occur. Project completion is scheduled for late 2011. Source


Richard M.J.,Simpson Gumpertz and Heger | Harries K.A.,University of Pittsburgh
Wood Science and Technology | Year: 2015

Bamboo materials are often characterized using standard tension coupon tests. However, due to the functionally graded nature of bamboo, the standard tension test geometry is inherently flawed and may result in additional non-uniform bending stresses being introduced across the breadth of the cross section during testing. An experimental programme highlighting issues with, and interferences present, in current methods and practices regarding the tensile strength of clear bamboo specimens cut from the culm wall is presented. The study investigates the influence of fibre gradation on the specimen behaviour using tensile specimens having different in situ orientation; these include ‘radial’ specimens engaging the full gradation of fibres through the culm wall thickness, and ‘tangential’ specimens taken from varying locations through the culm wall thickness perpendicular to the radial direction. The study also considered the end restraint condition provided by the testing machine—for which there is no guidance in applicable standards. Digital image correlation was used to measure variation in strain in the test specimens related to their native orientation in the bamboo culm. Fibre density across the culm wall thickness and the end restraint conditions of the specimens were shown to have an influence on bamboo tensile test results and therefore must be considered in the development of improved standard test methods. It is recommended that tangential specimens are used since they possess a more uniform fibre density throughout their cross section and taken together can outline the fibre density and strength in the radial direction through the culm wall. Fixed end restraints result in marginally lower measured tensile strengths having marginally improved variation. © 2014, Springer-Verlag Berlin Heidelberg. Source


Lamalva K.J.,Simpson Gumpertz and Heger
Journal of Fire Protection Engineering | Year: 2011

This article examines the influence of thermal boundary conditions used for the standard fire resistance test compared to those, which naturally exist in actual building construction. Two protected structural steel assemblies that vary in connection proximity to columns are analyzed. Using finite element modeling, the two assemblies are exposed to a simulated uncontrolled office fire with varying thermal boundary conditions. The modeling results demonstrate an acute effect that heat dissipation may have on the steel temperature distribution of a given structural assembly in an actual application. © 2011 The Author(s). Source

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