John E. Crawford

Bio: John E. Crawford is an academic researcher from Naval Facilities Engineering Service Center. The author has contributed to research in topics: Finite element method & Meshfree methods. The author has an hindex of 13, co-authored 34 publications receiving 1299 citations.

Dynamic Increase Factors for Concrete

Abstract: : For reinforced concrete structures subjected to blast effects, response at very high strain rates (up to 1000 s(-1)) is often sought. At these high strain rates, the apparent strength of concrete can increase significantly. The dynamic increase factor (DIF), i.e. the ratio of the dynamic to static strength, is normally reported as function of strain rate. For concrete, the DIF can be more than 2 in compression, and more than 6 in tension. Knowledge of the DIF is of significant importance in the design and analysis of structures for explosives safety. DIF curves for concrete have been published in manuals by the Tri-Services, the Defense Special Weapons Agency, the Air Force, and the Department of Energy. However, these curves are typically based on limited data. A literature review was conducted to determine the extant data to characterize the effects of strain rate on the compressive and tensile strengths of concrete. This data support the dynamic increase factor (DIF) being a bilinear function of the strain rate in a log-log plot. The DIF formulation recommended by the European CEB was described, together with its origins. For tension, it was found that the data differed somewhat from the CEB recommendations, mostly for strain rates beyond 1 s(-1), and an alternate formulation was proposed based on the experimental data.

Use of Composites to Resist Blast

Abstract: Buildings are vulnerable to blast loads from accidental or terrorist explosions. Key structural components, such as columns, can be shattered and result in the collapse of the whole building and a large number of casualties. Recent retrofit procedures have shown that composites can be used to strengthen structural components so that they can survive the blast load and maintain their load carrying capacity, insuring that building integrity is not affected. This paper is a review of the use of composites for retrofitting key structural components such as columns, beams, and walls subjected to blast loading.

Retrofit of Reinforced Concrete Structures to Resist Blast Effects

Abstract: Analyses were conducted to demonstrate the effectiveness of jacketing columns of existing reinforced concrete multistory buildings to improve their survivability to attacks by explosives. Different standoff distances, charge sizes, and steel and composite jackets were considered. Two building designs were analyzed: one in which the building members were designed primarily for gravity loads (UBC seismic zone 1) and one in which the members were designed to resist seismic loads (UBC seismic zone 4). Structural response predictions were performed with the three-dimensional Lagrangian finite element code DYNA3D, using a concrete material model especially designed to predict nonlinear concrete responses to explosive loads. The results indicate that jacketing can be an effective means to retrofit an existing facility to lessen its vulnerability to blast loads.

Fiber-Reinforced Polymer Composites for Construction—State-of-the-Art Review

Abstract: A concise state-of-the-art survey of fiber-reinforced polymer (also known as fiber-reinforced plastic) composites for construction applications in civil engineering is presented. The paper is organized into separate sections on structural shapes, bridge decks, internal reinforcements, externally bonded reinforcements, and standards and codes. Each section includes a historical review, the current state of the art, and future challenges.

Fiber-Reinforced Polymer Composites for Construction—State-of-the-Art Review

Abstract: A concise state-of-the-art survey of fiber-reinforced polymer (also known as fiber-reinforced plastic) composites for construction applications in civil engineering is presented. The paper is organized into separate sections on structural shapes, bridge decks, internal reinforcements, externally bonded reinforcements, and standards and codes. Each section includes a historical review, the current state of the art, and future challenges.

Nonlinear Finite Elements For Continua And Structures

Abstract: nonlinear finite elements for continua and structures is available in our book collection an online access to it is set as public so you can get it instantly. Our books collection saves in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the nonlinear finite elements for continua and structures is universally compatible with any devices to read.