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原文传递 Performance and Serviceability of HPS Girders, MO224 Lafayette County. Research rept.

题名：	Performance and Serviceability of HPS Girders, MO224 Lafayette County. Research rept.
作者：	BARKER, M. G.
关键词：	Girders-; Girder-bridges; Steel-structures; Service-life.;Performance-evaluation; Missouri-; Deflections-; Loads-Forces; Field-tests; Accelerated-tests.
摘要：	The Missouri Department of Transportation (MoDOT) built the states first High Performance Steel (HPS) Bridge in 2002. MoDOT Bridge A6101 uses HPS70W in the design of the 138 ft 138 ft two-span, five girder bridge. Design calculations show that using HPS only in the highly stressed regions (hybrid design) led to a superstructure steel weight savings of nearly 17%and an estimated cost savings of approximately 11%compared to a conventional 50ksi bridge. The University of Missouri-Columbia worked with MoDOT to instrument, field test, analyze, and evaluate the performance of the completed Bridge A6101. The tests concentrated on strength and serviceability behavior of the structure. The serviceability field testing of Bridge A6101 confirms that MoDOT uses conservative deflection criteria. The maximum measured deflections for an equivalent HS20 loading match closely to the AASHTO method of estimating deflections. The MoDOT approach significantly over-estimates the measured deflections. The conservative serviceability procedures used by some states, such as MoDOT, will cause many HPS designs to be controlled by deflection, such as A6101 was, instead of strength parameters, which negates the benefit of using higher strength materials. The strength performance testing involved comparing design capacities to equivalent experimental design capacities. For design, the minimum design capacity is an HS23.8 truck loading whereas the critical experimental design capacity is an HS26.2. Thus, this bridge does exhibit additional capacity over the design prediction. Although design predictions seem to be conservative for interior girders, they may be unconservative for exterior girders. Like in many progressive states, the future of HPS is promising in Missouri. HPS70W is a superior steel that can lead to more economical bridges than conventional 50ksi designs. HPS can produce significant savings, especially when used in hybrid designs with 50W or HPS50W. However, the conservative serviceability procedures used by some states, such as MoDOT, will cause many HPS designs to be controlled by deflection, such as A6101 was, instead of strength parameters, which negates the benefit of using higher strength materials.
报告类型：	科技报告