Seismic Performance of Conventional Wood-Frame Buildings (original) (raw)
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Seismic Reliability of Low-Rise Nonsymmetric Woodframe Buildings
Seismic responses and reliability of a one-story L-shaped woodframe building tested at the CSIRO Structures Laboratory and a hypothetical two-story L-shaped building based on the test house were investigated using a three-dimensional hysteretic frame model under bidirectional ground motions. Parameters of the degrading and pinching hysteresis used for the shear walls were identified from whole house testing. The SAC ground motions for the Los Angeles area were used and the effects of torsion, bidirectional excitations, the variability in ground motion, structural modeling, collapse capacity, and vibration period were investigated. It was found that uncertainties due to ground motion and structural modeling are the major sources for increase in estimated structural demand. Coupling of torsion and bidirectional excitation also causes significant response magnification. Overall, the adverse effects considered could cause more than 150% increase in demand or, in probabilistic terms, a 1 order of magnitude increase in exceedance probability for a given demand. These findings could be helpful in putting into context the findings and conclusions of analytical studies of woodframe building performance under earthquakes that ignore these uncertainties and effects. Torsion should be minimized in design to alleviate coupling magnification with bidirectional excitations.
A new method to assess the seismic vulnerabilityof existing wood frame buildings
2013
This paper aims at applying a direct displacement-based method to assess the seismic vulnerability of existing multi-storey wooden buildings. This procedure is consistent with Priestley's direct methodology firstly developed for reinforced concrete structures. The distinctive characteristic of the proposed method is that the system response is quantified through the use of displacements instead of equivalent elastic strengths, according to the traditional force-based approaches. Consequently, in comparison to common force-based procedures, this method cannot only be considered as a rational alternative but also as a new seismic philosophy to design or assess structures. A representative timber construction system commonly used in Italy was selected as case study. The construction system illustrated in this work was analysed in detail, with special attention given to the mechanical connections typically used. The typical failure mechanisms and the energy dissipation capacity of the structure or of its members were identified on the basis of the mechanical properties of structural parts and connections, as well as of their geometry. In the proposed direct displacement-based assessment approach, the seismic intensity that would cause the limit state to be exceeded can be calculated by means of simple formulas. Therefore, the capacity to demand ratio can be simply derived. The procedure could be used to gauge the likelihood of losses, by combining it with simple loss models to account for probabilistic aspects.
Study on Seismic Performance of Traditional Wooden Structure by Full Scale Shaking Table Tests
Journal of Structural and Construction Engineering (Transactions of AIJ), 2010
Full-scale shaking table tests were carried out at E-Defense to evaluate the seismic performance of a traditional wooden residential structure. The specimen was a post-and-beam frame with a plan dimension of 5.91 × 11.82 m and height of 7.53m. A key feature of the specimen was the oversized beams and columns. The design seismic load resistance was provided entirely by mud plaster walls. The beam-to-column joints were achieved by an oak peg using no metal fasteners. Under BCJ-L2 shaking, the first story exhibited a story drift of 3.7%, and one of the corner columns cracked. At that stage, many of the mud-plaster walls had crumbled. The maximum recorded base shear coefficient was 0.5.
Seismic Demands and Capacities of Single-Story and Low-Rise Multi-Story Woodframe Structures
2004
SUMMARY This paper summarizes a systematic process for the evaluation of seismic demands imposed by ground motions on single-story and low-rise woodframe structures. This process involves development of representative sets of ground motions and scaling them to specific hazard levels, development of analytical component models that closely simulate experimental results (including monotonic and cyclic strength deterioration), and utilization of analytical models in the development of a new representation of seismic ...
Procedia Engineering, 2011
In July 2009 a full-scale mid-rise light-frame wood apartment building was subjected to a series of earthquakes at the world's largest shake table in Miki, Japan. This paper focuses on (1) the design and construction of this 1350 m 2 fullscale building, and (2) the performance of the building at three different ground motion intensities. The test results of the six-story light-frame wood building are examined in detail. The objectives of the testing program were to (1) demonstrate that the performance-based seismic design procedure developed as part of the U.S.-based NEESWood project worked on the full scale building, i.e. validate the design philosophy to the extent one test can; and (2) gain a better understanding of how mid-rise light-frame wood buildings respond, in general, to a major earthquake while providing a landmark data set to the seismic engineering research community. The building consisted of 1350m 2 of living space and had twenty-three apartment units; approximately half one-bedroom units and half two-bedroom units. The building was subjected to three earthquakes ranging from seismic intensities corresponding to the 72 year event to the 2500 year event for Los Angeles, CA. In this paper the construction of the NEESWood Capstone Building is explained and the resulting seismic response in terms of base shears, selected wall drifts, global inter-story drifts, accelerations, hold-down forces, and roof drifts are presented. Detailed damage inspection was performed following each test and those results will be summarized also. The building performed excellently with little damage even following the 2500 year earthquake. The global drift at roof level was approximately 0.25 meters and maximum inter-story drifts were approximately 2% for the floor average with individual wall drifts reaching just over 3% in one corner of the building at the fifth story.
State of the art: Seismic behavior of wood-frame residential structures
There are about 80 million single-family dwellings (SFDs) in the United States, predominantly of wood-frame construction. Of these, 68% are owner-occupied. A home is typically the largest single investment of a family, and is often not covered by earthquake insurance, even where it is available. Of all the houses in America, 50% were built before 1974, and 76% built before 1990. Most wood-frame SFDs (WFSFDs) were built to prescriptive code provisions before seismic requirements were introduced. After the introduction of seismic design requirements, the importance of examining structures as an assembly of connected elements became more common. Much of the seismic design information on SFD construction is based on educated opinion or limited research. This review examines research that can be applied to WFSFD seismic analysis and the design and retrofit of existing WFSFDs. The review is intended to cover most readily available papers published in major U.S. journals and at major conferences in the area of seismic modeling, testing and evaluation. The state of the art is reviewed of seismic experimentation and seismic evaluation, and observations and recommendations are provided for future research.
Timber frame houses resistant to dynamic loads - seismic analysis
MATEC Web of Conferences, 2018
The aim of the article is to present results of seismic analysis results of two real-sized timber frame buildings subjected to seismic excitations. The first model was insulated with mineral wool, the second one with polyurethane foam. Technology and specifications involved in both models construction is based on the previously conducted experimental research on timber frame houses, including wall panels tests, wall numerical models and study on material properties and precisely reflect results of the those research. During the seismic analysis reference node located in buildings were selected. In selected node displacement values were measured and compared between two analyzed models. The results of the numerical analysis presented in the article indicate that the application of polyurethane foam for a skeleton filling of the timber-frame building leads to the increase in stiffness as well as damping of the whole structure, which results in a considerable increase in the seismic resistance of the structure.
Experimental Seismic Response of a Full-Scale Six-Story Light-Frame Wood Building
Journal of Structural Engineering, 2010
In July 2009, a full-scale midrise light-frame wood apartment building was subjected to a series of earthquakes at the world's largest shake table in Miki, Japan. This article focuses on the test results of that full-scale six-story light-frame wood building. The objectives of the testing program were to ͑1͒ demonstrate that the performance-based seismic design procedure developed as part of the NEESWood project worked on the full-scale building, i.e., validate the design philosophy to the extent one test can and ͑2͒ gain a better understanding of how midrise light-frame wood buildings respond, in general, to a major earthquake while providing a landmark data set to the seismic engineering research community. The building consisted of 1 , 350 m 2 ͑14, 000 ft 2 ͒ of living space and had 23 apartment units; approximately one-half one-bedroom units and one-half two-bedroom units. The building was subjected to three earthquakes ranging from seismic intensities corresponding to the 72-year event to the 2,500-year event for Los Angeles. In this paper, the construction of the NEESWood Capstone Building is explained and the resulting seismic response in terms of base shears, selected wall drifts, global interstory drifts, accelerations, hold-down forces, and roof drifts are presented. Detailed damage inspection was performed following each test and those results are summarized also. The building performed excellently with little damage even following the 2,500-year earthquake. The global drift at roof level was approximately 0.25 m and maximum interstory drifts were approximately 2% for the floor average with individual wall drifts reaching just over 3% in one corner of the building at the fifth story.
The 2019 Full-Scale Shake Table Test Program of Wood Dwellings
2020
The 2019 full-scale shake table test program of wood dwellings is addressed in this paper. The current Japanese seismic design guidelines were applied and two Grade-3 index buildings were prepared. One adopted the Post-and-Beam Structure (A-building), and the other the Shear-Wall structure (B-building). A series of tests planned very different physical boundary conditions surrounding their reinforced concrete foundations. In the first Phase 1, A-building was equipped with a base-isolation system, while B-building represented a generic foundation constructed on real soil by preparing a rigid soil box. In the second Phase 2, the foundation of A-building was firmly fixed, while cast-iron plates were installed beneath the foundation of B-building to control the friction resistance of the foundation. In the third Phase 3, the damaged first-story of A-building was retrofitted, and the foundation of B-building was firmly fixed. The two test buildings were densely instrumented with both con...
Engineering Structures, 2019
This paper studies the seismic performance of a six-story mid-rise woodframe building under long duration ground motions. The prototype structure was designed by using a performance-based seismic design (PBSD) approach and tested on a shake table at full-scale as part of the NEESWood Project. A three-dimensional finite element model of the structure was developed using the Timber3D program and validated using the shake table test data. Two sets of short and long duration records that had approximately the same response spectra were used for nonlinear dynamic analyses. Fragility curves developed by incremental dynamic analysis (IDA) showed the median collapse capacity of the structure was reduced by 18% for long duration motions compared to the capacity for short duration motions. At the maximum considered earthquake (MCE) intensity level, the estimated median Park and Ang damage index of the structure for long duration motions was increased by 36%.