Iowa's Leadership in Research and Development, 2010

Pentagon-classified navigation systems are designed and tested. Genetically-superior, drought resistant triple-stacked corn hybrids exponentially improve corn and soybean yields. Scientists discover a simple flower, the marigold, unlocks astonishing potential as a change agent to improve the world’s health. All achieved or discovered in Iowa, the common denominator among all of these extraordinary activities is the intensive research and development efforts involved in bringing them to market. For businesses heavily dependent on research and development, one of their strategic advantages of conducting that world-changing research in Iowa is the state’s Research Activities Credit, commonly referred to as the Research and Development tax credit. Whether a company’s specific strategy is planting a stake into emerging markets, expanding its market leadership position, or paving technological inroads to gain market share, the success of those efforts is largely dependent on the company’s preceding work in research and development. Iowa recognizes how significant these resulting innovations are to long-term business growth and stability. Even though the federal research credits have fluctuated with intermittent expiration dates and reinstatement periods, Iowa has remained consistent in its support for the Research Activities Credit over theyears.

Determination of entrance loss coefficients for pre-cast reinforced Concrete Box Culverts, December 2012

There is an increased interest in constructing Pre-Cast (PC) Twin and Triple Reinforced Concrete Box (RCB) culverts in Iowa due to the efficiency associated with their production in controlled environment and decrease of the construction time at the culvert sites. The design of the multi-barrel PC culverts is, however, based on guidelines for single-barrel cast-inplace (CIP) culverts despite that the PC and CIP culverts have different geometry. There is scarce information for multiplebarrel RCB culverts in general and even fewer on culverts with straight wingwalls as those designed by Iowa DOT. Overall, the transition from CIP to PC culverts requires additional information for improving the design specifications currently in use. Motivated by the need to fill these gaps, an experimental study was undertaken by IIHR-Hydroscience & Engineering. The goals of the study are to document flow performance curves and head losses at the culvert entrance for a various culvert geometry, flow conditions, and settings. The tests included single-, double- and triple-barrel PC and CIP culverts with two span-to-rise ratios set on mild and steep slopes. The tests also included optimization of the culvert geometry entrance by considering various configurations for the top bevel. The overall conclusion of the study is that by and large the current Iowa DOT design specifications for CIP culverts can be used for multi-barrel PC culvert design. For unsubmerged flow conditions the difference in the hydraulic performance curves and headloss coefficients for PC and CIP culverts are within the experimental uncertainty. Larger differences (specified by the study) are found for submerged conditions when the flow is increasingly constricted at the entrance in the culvert. The observed differentiation is less important for multi-barrel culverts as the influence of the wingwalls decreases with the increase of the number of barrels.