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Seismic Analysis Package for Woodframe Structures

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Version 2.0.1 - published on 26 Oct 2010

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This analysis program, developed based on the Seismic Analysis of Woodframe Structures (SAWS) and Computer Program for the Cyclic Analysis of SHEar Walls (CASHEW) (see Folz and Filiatrault, 2002) concepts, is aimed at providing both researchers and practitioners with a user-friendly software package which is capable of performing nonlinear seismic structural analysis and loss analysis for woodframe structures. In addition to time domain analysis, several modules that support the NEESWood PBSD efforts are included and described in Section 1.2. This software package is used extensively in the NEESWood project and may have upgrade versions depending on the advancement in analysis models for light frame wood structure. SAPWood is essentially a toolbox which allows the user to model a light frame wood structure for various seismic-related analyses. There are three types of models currently available in SAPWood: the first one is a bi-axial structural model which was introduced by Folz and Filiatrault (2002) in the SAWS program (3DOF in each story with a rigid diaphragm assumption); the second one is a simplified lumped-mass shear building model (with only 1DOF at each story level), which can be useful for preliminary uni-directional analysis and simplified design approaches; and a fully coupled bi-axial shear and bending model (triaxial model, Pei and van de Lindt, 2009, van de Lindt et al. 2010). The triaxial model also has the option for users to add friction pendulum base isolators to the base level. SAPWood also provides the user the ability to build and analyze light frame wood shearwalls using nonlinear connectors (nails, hold-down devices, screws, etc.) elements. This enables the analysis of woodframe structures beginning at the fastener level when assembly (shearwall) test data is not available. The module termed SAPWood-Nail Pattern (NP) analysis is designed to perform this task (the concept is similar to the CASHEW program developed in the CUREE-Caltech project with some modifications). See user manual in “Supporting Documentation” for more detail.


The NEESWood Project is a four-year five-university project headquartered at Colorado State University. The project director is John W. van de Lindt at Colorado State University (now at University of Alabama), and Co-Investigators are Rachel Davidson at the University of Delaware, Andre Filiatrault at the University at Buffalo, David V. Rosowsky at Texas A&M University, and Michael Symans at Rensselaer Polytechnic Institute. The objective of the NEESWood Project is to develop a logical and economical performance based seismic design philosophy to safely increase the height of woodframe construction in regions of moderate to high seismicity.

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Funding for this study was provided through the National Science Foundation’s George E. Brown, Jr. Network for Earthquake Engineering Research (NEES-R) program via NSF grant CMMI-0529903. That funding is gratefully acknowledged.

Cite this work

Researchers should cite this work as follows:

  • John Willem van de Lindt; Shiling Pei (2010), "SAPWood,"

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