and to design improved earthquake-resistant struc- 

 tures. 



Earthquake behavior of fine grained soil. Through 

 a grant to Cornell University, basic research has 

 been conducted into the dynamic behavior of fine 

 grained soils during earthquake excitations. Basic 

 results which have been accomplished are: (1) A 

 fundamental theoretical model for strength 

 changes of fine grained saturated soils subjected to 

 repeated loads; (2) an evaluation of the influence 

 of loading frequency on the behavior of undrained 

 fine grained soils; and a theoretical model for the 

 influence of undrained creep which has been for- 

 mulated and evaluated by tests; and (3) the devel- 

 opment of a model for the long-term drained ef- 

 fects of load repetition on fine grained soils. Such 

 results have significant impact on improved build- 

 ing construction, submarine landsliding, transpor- 

 tation facilities, and general construction activities. 



Research on reinforced concrete material. 



Fundamental research has been conducted by 

 Cornell University on the shear transfer in thick- 

 walled reinforced concrete structures under seis- 

 mic loading. The research involved the fundamental 

 behavior of the concrete in transferring the inter- 

 nal shear forces carried by the longitudinal steel, 

 the stirrup steel, the concrete cracked section, and 

 the compression zone of the concrete. The shear 

 transfer mechanism for static loads as well as cy- 

 clic loads was investigated to develop an under- 

 standing of the transfer action. The investigation 

 developed a new concept of the transfer mecha- 

 nism through the cracked interface of the particles 

 with a better understanding of the action and the 

 role of the longitudinal steel and the stirrup steel. 



Ground motion studies. Several fundamental 

 studies have been undertaken by academic re- 

 searchers aimed at improving the basic under- 

 standing of earthquake ground phenomena with 

 various geological and seismological conditions. 



A versatile earthquake model has been devel- 

 oped by researchers at the Massachusetts Institute 

 of Technology based upon consideration of shear 

 cracks with finite cohesive forces propagating and 

 skipping past the fault barriers. This model can 

 explain a variety of fault or ruptured zone effects 

 in the earth, including fault segmentation and rock- 

 bursts, ripples in seismograms which cannot be 

 explained by path eff'ect, and departure of scaling 

 law of seismic spectrum from that based on sim- 

 ilarity assumption. 



The University of California at Berkeley has 

 studied the stochastic characterization of ground 

 motion and has developed synthetic means to gen- 

 erate analytically artificial earthquake motions in 

 terms of random waves and energy pulses compat- 

 ible with actual data. Three-dimensional stochastic 



representations of earthquake ground motions 

 have been developed which provided a reliable 

 basis for explaining real behavior of ground re- 

 sponding to seismic waves and transfer of ground 

 motion forces to the structures. 



Fire research. As part of its fire research pro- 

 gram (recently transferred to the U.S. Department 

 of Commerce), RANN supported a project at the 

 University of Utah Flammability Research Center 

 to develop analytical procedures that would better 

 characterize the nature of the combustion process- 

 es of polymeric materials with respect to smoke 

 generation and determine the physiological and 

 toxicological consequences resulting from human 

 exposure during smoke-producing combustion. 

 The research resulted in an animal model for deter- 

 mining the relative inhalation toxicity under fire 

 stress conditions. The model permits simultaneous 

 evaluation of physiological parameters (blood, cen- 

 tral and peripheral nervous system, and respira- 

 tion) and behavioral aspects for determining sur- 

 vival response. It is the most advanced model 

 available and could form the basis of new testing 

 standards. An example of its usefulness is illustrat- 

 ed by the identification of a highly specific toxicant 

 generated in combustion of a particular fire- 

 retardant urethane foam. As a result, it appears to 

 be unwise to use phosphorous-containing fire retar- 

 dants in combination with low-molecular-weight 

 adducts of trimethylolpropane. 



Inadvertent weather modification. RANN has 

 supported research to delineate the mechanisms 

 whereby, and the extent to which, an agricultural 

 region modifies its own climate, and an urban area 

 modifies its surrounding weather, precipitation, 

 and aerosol. Some fairly basic knowledge has been 

 generated in the following areas: 



• Cloud physics. Gaseous and particulate emis- 

 sions from urban-industrial areas result in al- 

 tered concentrations and size distributions of 

 cloud active nuclei and modified cloud micro- 

 physical and precipitation physics processes. 

 Urban areas in general (University of Chica- 

 go) and specific fossil fuel power plants 

 (University of Washington) do not produce 

 significant amounts of ice-forming particles; 

 in fact, there is some evidence that pollutants 

 may inhibit ice formation on natural nuclei. 

 Sulfur g?ses undergo conversion to small 

 particles which quickly reach detectable siz- 

 es. Urban and industrial areas are prolific 

 sources of these small particles (University of 

 Wyoming, University of Chicago), and 

 plumes of these particles are often coincident 

 with plumes of sulfur gases. With continued 

 growth, these particles reach sizes where they 

 can nucleate cloud drops (CCN). Concentra- 

 tions of such particles are maximized down- 



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NATIONAL SCIENCE FOUNDATION 



