GIS: New York's Pipe Dream
To be of any use to managers, infrastructure data must be compiled in a form they can use. The answer for the 1990s is a geographic information system that electronically combines data...
Seismically Safe, Spectator-Friendly
As 50,000 frightened spectators at Candlestick Park can attest, the Loma Prieta earthquake in 1989 provided chilling evidence of the importance of seismic design in public structures....
Peaches and Concrete
One Peachtree Center, Atlanta's latest highrise tower, will measure 62 stories high (860 ft) with 1.42 million sq ft of office space when completed next July. It will also...
L'Ambiance Plaza: What Have We Learned
In April 1987, a structure called L'Ambiance Plaza collapsed during construction, killing 28 workers. The building, in Bridgeport, Conn., was being built using the lift-slab...
Making Teamwork Work
From consulting firms to steel workers, most work groups would benefit enormously from developing better teamwork, but making it happen isn't easy. Excerpts from
Engineering a Monument, Evoking a Nightmare
Rather than simply standing as a backdrop for exhibits, the $53.2 million U.S. Holocaust Memorial Museum is intended to be part of the fabric of the exhibition itself. Now under construction...
Tackling Trapped Sediments
Crater-sink fluidization has been used to recover sediment from harbors for the past couple of decades. Can this method bypass sediment around dams and return it to eroded beaches, solving...
A New Fast Track for Public Works
Most public contracts are still awarded to the lowest bidder, but some states are experimenting with other approaches for complex projects. In Oregon, officials facing a tight deadline...
Passive Acoustic Emission for Quantitative Evaluation of Freeze Thaw and Alkali Aggregate Reaction in Concretes
Several experiments are reported in which the progression of freeze thaw (FT), alkali-aggregate reaction (AAR), and internal cracking caused by mechanical loading were monitored using...
Damage Assessment in Concrete Using Acoustic Emission
An acoustic emission (AE) is a localized rapid release of strain energy in a stressed material. This energy release causes stress waves to propagate through the specimen. These acoustic...
Study of Three Dimensional Crack Tip Location of Mortar by Acoustic Emission
Plain mortar specimens were tested under three-point bending. Experimental variables include the width of the specimen and the notch-to-depth ratio. The experimental results of 12 specimens...
A feasibility study for a Concrete Core Tomographer
This is a study of the feasibility of applying computer tomography in the study of concrete cores. A laboratory protocol is presented for testing concrete cores using a medical - grade...
Real-Time Condition Monitoring of Concrete Structures by Embedded Optical Fibers
Fiber optic sensor methodology has matured to the point where the impact of this new technology is now evident, especially in aeronautics and space structure applications. External perturbations...
Concrete Beam Testing with Optical Fiber Sensors
The use of an embedded multimode optical fiber to monitor curing and load-to-failure testing of a reinforced concrete beam has been investigated. The embedding process used to network...
Sonic NDE of Structural Concrete
Case histories are presented to illustrate applications of nondestructive evaluation (NDE) methods that use stress waves to characterize the conditions of concrete construction. The case...
Evaluation of Concrete Bridges by Impact-Echo
Strength of post-tensioned bridge structural members primarily depends on the tensile capacity of their post-tensioning steel reinforcement. To prevent corrosion, the post-tensioning steel...
A Critique of the Ultrasonic Pulse Velocity Method for Testing Concrete
The pulse velocity method is the most widely used ultrasonic nondestructive method for assessing concrete quality. However, it has been well established that the relation between ultrasonic...
Frequency Spectrum Analysis of Ultrasonic Testing Signal in Concrete
Description is given on high-speed sample apparatus connected with the CTS-25 low frequency ultrasonoscope and computer, the time domain of ultrasonic testing signal is transformed to...
Evaluation of Compressive Strength for High-Strength Concrete by Pulse Velocity Method
Development of compressive strength and pulse velocity for high-strength concrete from the age of 5 hours are studied in relation to cementitious material types and curing conditions....
Condition Monitoring of Structures Using Transient Response
Condition monitoring of structures by measuring transient response and tracking the derived modal parameters has been applied with success in three laboratory studies. Where modal parameters...
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