AMERICAN PRACTICE IN SEISMIC DESIGN

SEISMIC DESIGN PRACTICE IS REVIEWED AGAINST THE UNDERLYING ASSUMPTIONS OF THE BASIC SEISMIC DESIGN EQUATIONS IN THE "UNIFORM BUILDING CODE." PRACTICE AND ASSUMPTIONS ARE TREATED UNDER THE TOPICAL HEADINGS DESIGN CRITERIA, DYNAMIC ANALYSIS, LATERAL DUCTILITY, AND ROTATIONAL DUCTILITY. A SECTION ON TEST RESULTS DEALS WITH THE BEHAVIOR OF PRESTRESSED CONCRETE AND WITH THE BEHAVIORAL DIFFERENCES BETWEEN PRESTRESSED AND REINFORCED CONCRETE. FROM TESTS AND STUDY OF THE ENGINEERING PROPERTIES OF PRESTRESSED CONCRETE, IT IS CONCLUDED THAT UNDERREINFORCED PRESTRESSED SECTIONS CAN SUPPLY THE DUCTILITY IMPLIED IN CODE PROVISIONS TO RESIST CATASTROPHIC EARTHQUAKES WITH AMPLE RESERVE CAPACITY. IN THE RANGE OF SEISMIC DISTURBANCES SLIGHTLY GREATER THAN MODERATE, PRESTRESSED CONCRETE CAN PROVIDE THE NECESSARY DEFORMABILITY AND STILL RESPOND ALMOST ELASTICALLY.