Patent ID: 8302351

Claim:
A vibration damper disposed in a vicinity of a joint portion in which framework members of a wooden construction are joined to each other, the damper comprising: a first plate that is fixed to a first framework member and projects from the framework member, a second plate that is fixed to a second framework member and projects from the framework member, and an elastic material that is filled in the interstices between the first plate and the second plate and join the first plate and the second plate, wherein a first clearance is formed between the second framework member and a first fixing portion by which the first plate is fixed to the first framework member; a second clearance is formed between the first framework member and a second fixing portion by which the second plate is fixed to the second framework member; the first plate is made of a steel plate that is formed directing from the first fixing portion to the second fixing portion; the second plate is made of a steel plate that is formed directing from the second fixing portion to the first fixing portion; and a space portion constituted by the first clearance, the second clearance, the first plate, and the second plate has a dimension which is at least sufficient for inserting a joist therein, wherein the elastic material is formed of a rubber composition including a base rubber composed of a polymer in which backbone has C—C bond, and added and cross-linked with silica and a silane compound, wherein 100 to 150 parts by mass of silica is added to 100 parts by mass of base rubber, and silane compound is added in a mass equal to 10 to 30% of a mass of the silica, wherein, in the elastic material, equivalent viscous damping coefficient Heq satisfies Heq>0.24 under conditions of 0° C. to 40° C., and within a range shear strain γ of 0.125≦γ≦3.0; a ratio of equivalent shear modulus Geq at γ=3 and Geq at γ=1 satisfies 0.40≦{Geq (γ=3.0) }/{Geq (γ=1.0) }<0.60; a damping capacity of the elastic material under a predetermined temperature has a rate of change of frequency from a base frequency within ±50% where the base frequency is within a range of 0.1 to 20 Hz; normalized by Geq at 20° C., a ratio between Geq(t=0° C.) at 0° C. and Geq(t=20° C.) at 20° C. satisfies Geq(t=0° C.)/Geq(t=20° C.)≦2.0, and a ratio between Geq(t=40° C.) at 40° C. and Geq(t=20° C.) at 20° C. satisfies Geq(t=40° C.)/Geq(t=20° C.)≧0.5; a dimension of deformation at the time of marginal deformation satisfies a strain ratio ≧400% within a range of 0° C. to 40° C.; and under aging conditions equivalent to aging of 60 years, aging deterioration of the elastic material evaluated by change of rate of Heq and Geq are within a range of Heq(60 years)/Heq(0 year)>0.8, and Geq(60 years)/Geq(0 year)<1.2.