Reliability of Wood Joist Floor Systems with Creep

Light-frame wood floors are constructed from a number of parallel flexural members (joists), which provide the primary structural support. Sheathing material is attached across the top edges of these joists to form the floor surface. Because the joists are connected in this manner, load sharing occurs, which enhances the performance of the system as a whole. Current design procedures focus on the behavior of single members with only limited provisions account for the improved performance of systems. In this study, the reliability of wood joist floors is investigated considering both strength and serviceability limit states. The objective of the system reliability analyses is to determine appropriate system factors for use in single member load and resistance factor design checking equations. These factors are included to account for the beneficial effects associated with systems of parallel members. This study considers factors such as lumber species and grade, floor size, and the effects of creep deformations. A stochastic viscoelastic stress-strain relationship is used to model the time-dependent behavior of wood, the stochastic pulse process models are used to account for the temporal variability of the loads. Cumulative damage analysis using two common damage accumulation models is used to account for the time-dependent strength of wood flexural members.

[1]  David V. Rosowsky,et al.  Serviceability Design in LRFD for Wood , 1993 .

[2]  Lawrence A. Soltis,et al.  Creep Behavior Model for Structural Lumber , 1992 .

[3]  James R. Goodman,et al.  Service and Overload Behavior of Wood Joist Floor Systems , 1974 .

[4]  Lawrence A. Soltis,et al.  Hygrothermal Effects on Mechanical Properties of Lumber , 1992 .

[5]  Marvin E. Criswell.  Selection of Limit States for Wood Floor Design , 1979 .

[6]  William M. Bulleit.  Relative Reliability of Dimension Lumber in Bending , 1985 .

[7]  Ricardo O. Foschi.  Structural Analysis of Wood Floor Systems , 1982 .

[8]  Bryan Folz,et al.  Reliability‐Based Design of Wood Structural Systems , 1989 .

[9]  Marvin E. Criswell.  Response of Realistic Wood Joist Floors , 1979 .

[10]  W J McCutcheon.  Deflections of Uniformly Loaded Floors. A Beam-Spring Analog. , 1984 .

[11]  Ricardo O. Foschi.  Wood Floor Behavior: Experimental Study , 1985 .

[12]  Judith J. Stalnaker,et al.  Structural Design in Wood , 1988 .

[13]  Bryan Folz,et al.  Reliability-based design of wood structures , 1989 .

[14]  William M. Bulleit.  Markov Model for Wood Structural Systems , 1987 .

[15]  R. G. Pearson.  Potential of the SB and SBB distributions fof describing mechanical properties of lumber. , 1980 .

[16]  R. C. Moody,et al.  Static Behavior of Wood‐Joist Floors at Various Limit States , 1986 .

[17]  Ricardo O. Foschi,et al.  Load-Duration Effects in Westerm Hemlock Lumber , 1982 .

[18]  James R. Goodman,et al.  Finite Element Analysis of Layered Wood Systems , 1975 .

[19]  Bruce R. Ellingwood,et al.  System Reliability and Load‐Sharing Effects in Light‐Frame Wood Construction , 1991 .

[20]  Theodore V. Galambos,et al.  Serviceability Limit States: Deflection , 1986 .