amardeep singh sohal

Review of Laminated Elastometric Bearing Pad (AASHTO M251 & BS 5400: Part 9) Steel-Reinforced Elastometric Bearings – Method B A. Allowable Delamination compressive Stress: 1. Shear Modulus (G) = 130 ~ 199 psi (Say Use 150 psi = 1.03 MPa) 2. Hardness -- Use 50 Durometer (Between 50 ~ 60 on Shore A scale) 3. Compressive Stress (AASHTO 14.7.5.3.2) In any elastometric bearing layer, the average allowable compressive stress at the service limit state shall satisfy: • For bearing subject to shear deformation: S: Shape factor (8.5 < S < 11) For total (all layers) thickness Service DL per bearing: DL = 300 kN (67.443 kips) Service LL per bearing: LL = 500 kN (112.404 kips) Existing L= 600mm W= 200 mm c= (DL+LL) / LW = 800*1000N/ (600x200)mm2 =6.67 MPa = 1 ksi <1.6 ksi hri: 6.4mm hrc: 6.3mm so, S=600*200/(2*6.4*(600+200))=11.7 (actual) c=6.67 MPa < (allowable) s=0.66x1.03x11.7 =7.95 MPa (1.2ksi) ……. OK B. Determine Bearing Pad

Specific Gravity Specific gravity is the ratio of density of a substance compared to the density of fresh water at 4°C (39° F). At this temperature the density of water is at its greatest value and equal 1 g/mL. Since specific gravity is a ratio, so it has no units. An object will float in water if its density is less than the density of water and sink if its density is greater that that of water. Similarly, an object with specific gravity less than 1 will float and those with a specific gravity greater than one will sink. Specific gravity values for a few common substances are: Au, 19.3; mercury, 13.6; alcohol, 0.7893; benzene, 0.8786. Note that since water has a density of 1 g/cm3, the specific gravity is the same as the density of the material measured in g/cm3. The Discovery of Specific Gravity The discovery of specific gravity makes for an interesting story. Sometime around 250 B.C., the Greek mathematician Archimedes was given the task of determining whether a craftsman had d