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The current design recommendations for concrete deep beams given in the ACI Code, Canadian Code, CEB-FIP Model Code, CIRIA Guide-2, etc., are based on research results on normal strength concrete. As such, these design recommendations may not be directly applicable to deep beams made of high-strength concrete. A summary of the authors' recent research on the shear behavior of deep beams made of high-strength concrete is presented. Experimental results on the ultimate shear strengths of single-span, continuous, and slender deep beams as affected by the strength of concrete, shear-span-to-depth ratio, and slenderness ratio, are compared to various design methods. It is found that the ACI method is overly conservative for all cases, the Canadian Code method is unconservative for higher strength concrete, the CEB-FIP method gives somewhat scattered predictions, and the CIRIA Guide-2 is slightly unconservative for all cases. A minor modification on the CIRIA Guide-2 method is shown to yield a reliable method for all the cases investigated.

An experimental investigation was conducted on the shear behavior of deep beams made with steel fiber reinforced high performance concrete (HPC). Twenty-six beam specimens with various shear span-effective depth ratios, steel fiber contents, amounts of vertical and horizontal web reinforcements were tested under static loads. In addition to the strength test, extensive instrumentations were designed for the measurements of average strains of reinforced concrete in the shear span and strains of web reinforcements. The web-shear cracking initiated as the first inclined shear crack. About 30% increase in the inclined shear strength and 25% increase in the ultimate shear strength can be achieved with addition of 1 .O% steel fiber for specimens having a/d= 1 .5. The strain of vertical web reinforcements became negative and the horizontal web reinforcements were stretched to yield state for specimens having a/d ratios approach 0.5. The measured load-deformation relationships of reinforced concrete and strains of web reinforcements were compared with the prediction of the softened truss model of steel fiber reinforced concrete proposed by other investigators. Good correlation was found from the comparisons.

The latest developments in concrete platform concepts for deep water and floating structures have indicated the need for further development in the field of practical concrete technology. Paper presents some of the most significant factors in this challenge such as increased compressive strength, improved workability, and stability of fresh concrete, use of high-strength lightweight aggregate concrete, measures to improve the concrete E-modulus, and utilization of variable concrete density to optimize the platform design. This has been achieved through further development of the constituent materials, refinements of the mix design, and advancements in production methods, as well as the use of high-quality lightweight aggregates.

The troll GBS platform is the world's largest concrete offshore concrete platform. The platform is designed for an operational lifetime of 70 years and will be installed in the North Sea during 1995. To improve the buoyancy of the platform during tow-out to the field, a concrete mixture with reduced density has been developed, providing a characteristic 28-day cube compressive strength of at least 75 MPa and an in situ density of 2250 kg/m 3. The weight reduction has been obtained by partly replacing the natural coarse aggregates by high-quality lightweight aggregates. The concrete is denoted as modified normal density (MND) concrete. The modification was expected to reduce both compressive strength, Young's E-modulus, and material ductility to some extent. A comprehensive testing program comprising laboratory tests and full-scale tests has been performed to investigate and to document all relevant concrete properties related to mechanical, durability, and constructibility performance of the concrete. A secondary purpose of the investigations has been to evaluate the possibility of retaining the mechanical properties of the original normal density concrete by replacing the remaining coarse granite aggregate with a more rigid quartz-diorite aggregate. The laboratory investigations included the determination of the following concrete properties: fresh concrete properties, compressive strength development, compressive strength at sustained load, compressive E-modulus, tensile strength and E-modulus, stress-strain in compression, fatigue, fracture energy and characteristic length, shrinkage, creep, water intrusion, and alkali-silica reactivity.

The chemical and petrochemical industries that process chemical and petrochemical products manufacture, store, and transfer a number of liquids that are hazardous to the environment and particularly to the groundwater. In Germany, uncoated concrete may be used only as a secondary barrier for handling water-hazardous materials. Development and optimization studies were carried out to reduce the permeability and increase the ductility of concrete for this application. Concretes with styrene-butadiene-based polymer dispersions and silica fume were produced to reduce the permeability, and concretes with limestone or expanded clay instead of Rhine gravel to improve ductility. The mechanical behavior of the concretes was characterized by determining the stress-strain curves under tensile and compressive loading and the stress crack-opening curves. Resistance to environmentally hazardous liquids was tested using a special penetration test standardized in Germany. Various organic liquids, each representing a main chemical group and of differing water solubilities and viscosities, were used as test media.