D.S. Brown can efficiently design, manufacture and test Versiflex™ high-load multi-rotational (Versiflex™ HLMR) pot and disc style, spherical, seismic isolation and elastomeric bearing assemblies for all types of construction.
Answer:
D.S. Brown fabricates elastomeric bearings meeting AASHTO LRFD Bearing Design. Shear modulus (G) is a critically important material property in the design and performance of elastomeric bearings. The designer should use the minimum and maximum values of G taken as the least favorable value in design calculations.
For bearings designed by method ‘A’, the least favorable range of values are provided in the Specifications for 50, 60 and 70 durometer hardness. The shear modulus range is broad since the design approach for Method ‘A’ is conservative. Bearings designed by method ‘A’ are specified by durometer hardness only, never by a shear modulus.
Bearings designed by method ‘B’, however are specified by a shear modulus only, never by durometer. The shear modulus specified must be between 0.080 and 0.175 ksi. The equations for Method ‘B’ are strain based and less conservative, so it is important to narrow the least favorable range. The compounding of elastomer includes many variables and it is unlikely that the same exact shear modulus can be achieved from batch to batch, so the least favorable range is ±15 percent of the specified shear modulus. Given the restrictions on the upper and lower allowable shear moduli, the designer should avoid specifying a shear modulus close to the upper and lower bound which could limit the acceptable range. From an economic standpoint, for any particular project, the designer should try to use one shear modulus for all designs.
The important message here is that one should not be specifying both a shear modulus and durometer.
Learn more about D.S. Brown Structural Bearing Assemblies
D.S. Brown is one of the leading suppliers of structural bearing assemblies.
Since 1963, The D.S. Brown Company has provided bearing assemblies and joint seals for bridges around the globe. Bridges and other large structures are supported on bearing assemblies to transmit forces while accommodating all structural movements.
The selection of an appropriate bearing assembly is based on the magnitude of vertical and horizontal forces transmitted through the bearing assembly, as well as the amount of displacement and rotation of the superstructure elements. In addition, special attention to the bearing assembly design may be necessary when, for example, larger than normal horizontal loading or uplift situations exist.
With extensive experience and utilizing the latest technologies, D.S. Brown can efficiently design, manufacture and test Versiflex™ high-load multi-rotational (Versiflex™ HLMR) pot and disc style, spherical, seismic isolation and elastomeric bearing assemblies for all types of construction.
D.S. Brown is available to work closely with bridge owners and engineering design consultants to assist in the design, selection and testing of the proper structural bearing assemblies.