The Flexural Fatigue Strength of Prestressed Steel I-Beams, HR-73, 1962

The purpose of this investigation was to study the flexural fatigue strength of two prestressed steel I-beams which had previously been fabricated in connection with a jointly sponsored project under the auspices of the Iowa State Highway Commission. The beams were prestressed by deflecting them under the action of a concentrated load at the center of a simple span, then welding unstressed high strength steel plates to the top and bottom flanges to retain a predetermined amount of prestress. The beams were rolled sections of A36 steel and the plates were USS "T-1" steel. Each of the two test specimens were subjected to an identical repeated loading until a fatigue failure occurred. The loading was designed to produce stresses equivalent to those which would have occurred in a simulated bridge and amounted to 84 percent of a standard H-15 live load including impact. One of the beams sustained 2,469,100 repetitions of load to failure and the other sustained 2,756,100 cycles. Following the fatigue tests, an experimental study was made to determine the state of stress that had been retained in the prestressed steel beams. This information, upon which the calculated stresses of the test could be superimposed, provided a method of correlating the fatigue strength of the beams with the fatigue information available on the two steels involved.

Soil-Cement Stabilization, Part 1, Materials and Construction, HR-75, 1962

This report covers the construction in 1961 of the soil-cement base and related pavement structure on Iowa 37 from Soldier to Dunlap, (F-861(6), Crawford, Harrison, Monona). The report also contains an account of the experimental work performed on the same road under research project HR-75.

Curb Removal Study, HR-76, Progress Report, 1962

Pavements constructed in Iowa during the period of the 1920's through the late 1940's were built with an integral curb. The purpose of the curb was to control drainage of water from the pavement surface in areas where runoff took place at a very rapid rate. It is for this reason that curbing is found on pavements constructed during this period. The curbing led the water flowing on the pavement surface to drainage outlets; this helped reduce erosion along the edge of the slab. The curbs have satisfactorily performed the job for which they were intended. The advent of bigger and faster vehicles has created a demand for changes in the design of pavements. Current designs provide wider driving surfaces with reduced grades which can better accommodate the wider cars and trucks. By present day design standards the narrow highways are inadequate and are being replaced or improved. The normal improvement procedure is to widen to 24 feet by providing additional driving surface at each edge of the pavement. Curbing is removed from the pavement so that the surface of the widening can be placed at the same level as that of the slab.

Correspondance : 1812-1876. II. 1836-1847 / George Sand

Collection : Bibliothèque contemporaine

Correspondance : 1812-1876. V. 1864-1870 / George Sand

Collection : Bibliothèque contemporaine

Correspondance : 1812-1876. I. 1812-1836 / George Sand

Collection : Bibliothèque contemporaine

Correspondance : 1812-1876. IV. 1854-1863 / George Sand

Collection : Bibliothèque contemporaine

Correspondance : 1812-1876. VI. 1870-1876 / George Sand

Collection : Bibliothèque contemporaine

Correspondance : 1812-1876. III. 1848-1853 / George Sand

Collection : Bibliothèque contemporaine