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one had to go far to observe instances of reinforced concrete. Last sum- 

 mer in Seattle the writer saw no other tj'pe of building in process of con- 

 struction. At Atlantic City in 1902, when the experiments referred to were 

 placed before the American Society for Testing Materials, there was no 

 instance of the use of reinforced concrete in sight. Last summer, at the 

 meeting of the Society, one viewed the stately and beautiful Marlborough- 

 Blenheim hotel entirely constructed of reinforced concrete ; the replace- 

 ment of the steel pier by reinforced concrete piles and girders ; and the 

 construction of a new recreation pier of this type of construction. The 

 growth has been truly marvelous. Not only has the extent of its use in 

 bridges and buildings increased, but the variety of its application is extra- 

 ordinary. In a list of constructions in which it is successfully and eco- 

 nomically used may be included : Retaining walls, dams, tanks, conduits, 

 chinnieys, arches, culverts, foundations, floors for buildings, railroad gird- 

 ers, highway bridges, pipes, railway ties, piles, stairs and roofs. 



At the present time the underlying mechanical principles and the con- 

 stants of design are fairly well determined, and we wait upon the archi- 

 tects to express the truth of these principles in a beautiful structure. 

 While this type of construction associates itself with the broad and simple 

 wall spaces and low buildings of the Spanish Mission style, with surface 

 ornaments of tiling and Mosaic, it also lends itself to important modern 

 civic buildings. The stateiiness of beauty of the Marlborough-Blenheim 

 Hotel at Atlantic City has been mentioned. The Ingalls Building, Cincin- 

 nati, and the new Terminal Station at Atlanta, Ga., are other examples. 



Without stopping to discuss the properties of waterproofness, fire- 

 proofness, durability, etc., or the multitude of topics of interest 'and im- 

 portance that crowd one's mind in connection with reinforced concrete, at- 

 tention will be simply called to the mechanical principles underlying the 

 construction. 



Concrete, like stone, is weak in tension, but strong in compression at a 

 ratio of 1 to 10. Consequently when under flexure, as in a beam, the con- 

 crete is not used economically ; for it breaks on the lower side in tension 

 before the compressional strength is utilized. A beam may be, however, 

 strengthened, or reinforced, by the insertion of a steel rod in the lower 

 side of the beam. These rods are usually bent up near the ends of the 

 beam so as to also reinforce the beam against the diagonal tensional 

 stresses that occur at the ends, due to the combination of shear and direct 

 stress. 



