Carl Ealy

Class-A Prediction of Construction Defects in Drilled Shafts

The results of a blind Class-A prediction symposium of construction defects in drilled shafts are presented. Six drilled shafts were constructed at the National Geotechnical Experimentation Site in Amherst, Massachusetts. Several types of defects were integrated into the shafts, including necking, voids, caving, and soft bottoms. Seven organizations participated in a blind defect prediction symposium and used a variety of nondestructive testing techniques, including down-hole techniques, such as cross-hole sonic logging, single-hole sonic logging, and cross-hole tomography, and surface techniques, such as pulse echo and sonic mobility. Most participants found defects that were larger than 10 percent of the cross-sectional area. However, false positives and an inability to locate smaller defects and multiple defects in the same shaft were encountered.

AXIAL AND LATERAL LOAD PERFORMANCE OF TWO COMPOSITE PILES AND ONE PRESTRESSED CONCRETE PILE

Composite piles use fiber-reinforced polymers (FRPs), plastics, and other materials to replace or protect steel or concrete, with the intent being to produce piles that have lower maintenance costs and longer service lives than those of conventional piles, especially in marine applications and other corrosive environments. Well-documented field loading tests of composite piles are scarce, and this lack of a reliable database may be one reason that composite piles are not in widespread use for load-bearing applications. The purpose of this research is to compare the axial and lateral load behavior of two different types of composite test piles and a conventional prestressed concrete test pile at a bridge construction site in Hampton, Virginia. One of the composite piles is an FRP shell filled with concrete and reinforced with steel bars. The other composite pile consists of a polyethylene plastic matrix surrounding a steel reinforcing cage. The axial structural stiffnesses of the prestressed concrete pile and the FRP pile are similar, and they are both much stiffer than the plastic pile. The flexurel stiffness of the prestressed concrete pile is greater than that of the FRP pile, which is greater than the flexural stiffness of the plastic pile. The axial geotechnical capacities of the test piles decreased in order from the prestressed concrete pile to the FRP pile to the plastic pile. The prestressed concrete pile and the FRP pile exhibited a similar response for lateral load versus deflection, and the plastic pile was much less stiff in lateral loading.

User query interface for the deep-foundations load-test database

The deep-foundation load-test database is a result of research quality data collection over the past 15 years. The database consists of soils data along with the deep-foundations load-test data gathered from prototype tests conducted all over the world. The soils data include general site information, stratigraphy, laboratory, and in situ test details. The foundations data consist of general foundations information including foundation construction, and load-settlement information to failure. Over 1,000 foundations are currently in the database, and more are being added. The database is checked for its validity and correctness both before and after the data are added to the database to make sure that the data integrity is preserved. Also, the data are periodically backed up and the data input is strictly administered by providing controlled access to the designated individuals. The database is structured to follow the rules of relational database management systems (RDBMS). The database resides in a Unix-based Sun Solaris server, and the database engine is Sybase RDBMS. The database front-end query application is under development for the Internet using Java as the programming language and will run under any Internet-capable browser (e.g., Netscape, Microsoft Internet Explorer) environment. The application will use Java applets to communicate with the database server. The user community includes state highway engineers, geotechnical researchers, students, and practicing engineers. Interested users can access the database using the interface to view, download, and chart the data at run-time.