Shear links

An excellent example of such a steel tower is the new 525 ft (160 m) tower for the Suspension Span of the San Francisco-Oakland Bay Bridge East Span. This tower is composed of four separated pentagonal, cross-sectional shaped shafts, connected by shear-link beams. The tower shafts are separated about 2 m, allowing light to permeate between the shafts that are tapered toward the top to enhance their appearance. The shear-link beams are both attractive esthetic elements, and the structural steel beams yield in shear and absorb energy when activated by strong earthquakes (Figure 3.17). 

A Brief of Systematic EC-2 Design Fig. 10.5 Type of shear link... 

Mansour N, Christopoulos C, Tremblay R (2011) Experimental validation of replaceable shear links for eccentrically braced steel frames. J Stract Eng 137(10) 1141-1152... 

American Institute of Steel Construction (AISC) (2010) ANSI/AISC 341-10 seismic provisions for structural steel buildings. AISC, Chicago Gray MG (2012) Cast steel yielding brace system for concentrically braced frames. University of Toronto PhD dissertation. University of Toronto, Toronto Gray MG, Chiistopoulos C, Packer JA (2013) Cast steel yielding brace system (YBS) for concentrically braced frames concept development and experimental validations. ASCE J Struct Eng (in press). ASCE, Reston, Vol. 140, pp 04013095-1-04013095-11 Mansour N, Christopoulos C, Tremblay R (2011) Experimental validation of replaceable shear links for eccentrically braced steel frames. ASCE J Struct Eng 137(10) 1141-1152... 

Fig. 20 Damaged eccentrically brace frame, showing yielding of the shear link element ( RTLeon)...

Superabsorbents. Water-sweUable polymers are used extensively in consumer articles and for industrial appUcations. Most of these polymers are cross-linked acryUc copolymers of metal salts of acryUc acid and acrylamide or other monomers such as 2-acrylamido-2-methylpropanesulfonic acid. These hydrogel forming systems can have high gel strength as measured by the shear modulus (134). Sometimes inorganic water-insoluble powder is blended with the polymer to increase gel strength (135). Patents describe processes for making cross-linked polyurethane foams which contain superabsorbent polymers (136,137). 

The physical properties of polyurethane adhesives result from a special form of phase separation which occurs in the cross-linked polyurethane stmcture. The urethane portions of polyurethanes tend to separate from the polyol portion of the resin, providing good shear strength, good low temperature flexibiUty, and high peel strength. Catalysts such as dibutyltin dilaurate [77-58-7], stannous octoate [1912-83-0], l,4-diazabicyclo[2.2.2]octane... 

Tetraalkyl titanates react with organic borates, B(OR )2, to give complexes of the general formula Ti(OR)4 B(OR )2, which are useful as catalysts and cross-linking agents (562). Mixtures of chelated organic titanates such as TYZOR TE and TYZOR LA with alkaU metal borates, such as borax, or boric acid can be used to produce shear-stable fracturing fluids (563). 

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