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An experimental study was performed to investigate the effects of ground rubber, styrene-butadiene rubber latex, vegetable gum latex, and calcium carbonate on the material damping of concrete. The additives were introduced by volumetric replacements of fine aggregate up to 15%. Damping comparisons are made on the basis of specific damping capacity measured from cyclic loading tests of concrete cylinders. The results show that the highest tested concentration of vegetable gum latex more than doubles the specific damping. Also, the amount of specific damping for all mixtures is shown to be dependent on the amplitude of cyclic strain, a property not associated with viscous damping.
Keywords: admixtures; damping; energy; latex; rubber.
(ProQuest: ... denotes formulae omitted.)
INTRODUCTION
Many structures are sensitive to vibrations caused by wind, earthquakes, vehicular traffic, operation of machines, or human activity such as walking or dancing. In some cases, the vibrations may be excessive, resulting in damage to the structure, discomfort of human occupants, or disruption of the intended use of the facility.
As an example, floor systems of buildings are often constructed as composite systems with light steel beams or joists with a concrete deck. In many cases, the design of such systems is controlled by vibration criteria and specifically by the vertical accelerations caused by human activity. Because floor accelerations due to walking excitation are inversely proportional to the damping ratio,1 an increase in the material damping of the concrete slab could eliminate floor vibration as a serviceability consideration.
In tall buildings, wind load magnitude (in the form of the gust factor) and the structural acceleration response are also dependent on the damping in the system.2 Increases in damping reduce both the wind load magnitude and the dynamic response to that load. An increase in damping capacity of concrete would be particularly useful in tall, slender concrete shear wall systems. Such systems are often used for residential buildings, which have very low vibration tolerances.3
One way to increase the damping of these structures is to increase the damping of their structural materials. Because structural concrete is engineered on the basis of a mixture composition for each application, it is a natural choice for the development of a relatively high damping structural material. This has led to investigations of the...