2016 Volume 62 Issue 4 Pages 101-107
To clarify the static and dynamic properties of large-span wooden floors, we measured static deflection, bending stiffness, natural frequency and damping ratio of floors at four wooden schools and two wooden offices. The initial design deflection to span ratio was approximately 1/430 to 1/1100 for these floors. In addition, design deflections including creep to span ratio was approximately 1/280 to 1/800. These values were within the limitations defined by the Building Standards Law and the Standard for Structural Design of Timber Structures of the Architectural Institute of Japan, except for one elementary school. The experimental bending stiffness of beams or trusses was 1.1 to 3.9 times larger than the design value. On the other hand, the measured natural frequency of floors in actual wooden buildings ranged from 9.5 to 12 Hz. These values could be relatively accurately estimated using the theory of simply supported beams with applied dead loads. Additionally, the damping ratios ranged from 3.1 to 6.5%, almost the same as those in previous studies.
