Wednesday, September 8, 2010

Lexicon: Brunspile

As reported in Engineering News-Record 6 August 1964:

A 45-story, steel-framed skyscraper under construction in downtown New Orleans will set several structural records. The tallest building in the Old South, Plaza Tower will sit on pre-stressed concrete piles designed for bearing values of 180 tons, the greatest pile load ever approved in that city.

The $10-million tower will rise from one corner of an 18-story base building devoted largely to parking 500 cars. Duranodic aluminum will sheath closely spaced exterior columns. Between the columns, white marble spandrels will alternate vertically with bronze-tinted windows.

Before approving the 180-ton pile value, city building officials required load tests held for at least two days at more than double the allowable design load. Driven successively through strata of compressible clay again into a hard Pleistocene stratum (glacial till consisting mainly of hard clay) about 155 ft below grade, a 168-ft pile passed the test with ease. It held 400 tons for two days with only 3/8 in. residual settlement. At 462 tons, the test pile failed in compression (5,600 psi); the foundation soil still held.

Known as Brunspile, the piles are pre-stressed, precast units up to 70 ft long, octagonal in cross section. The splice detail comprises a cast-steel, cylindrical wedge connector into which fits the ferrule end of the top unit. The pile units are separated by a steel impact plate, and pile hammer blows wedge the two sections together in a moment-resisting joint...

To read more, consult ENR in Howard-Tilton Memorial Library. Architect for the Plaza Tower was Leonard Spangenberg, Jr. & Assoc. Tulane University's William J. Mouton was consulting engineer, George A. Fuller of Dallas was general contractor, and Stephen K. Whitty of New Orleans was pile subcontractor.

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