John W. van de Lindt

Experimental Seismic Response of a Full-Scale Six-Story Light-Frame Wood Building

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 (1) 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 (2) 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  m2 ( 14,000  ft2 ) 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-yea...

Simplified Direct Displacement Design of Six-Story Woodframe Building and Pretest Seismic Performance Assessment

This paper presents a simplified direct displacement design DDD procedure which was used to design the shear walls for a six-story woodframe structure. The building was tested in the final phase of a Network for Earthquake Engineering Simulation NEES project. Specifically, NEESWood Capstone Building was designed to meet four performance expectations: damage limitation, life safety, far-field collapse prevention CP, and near-fault CP. The performance expectations are defined in terms of combinations of interstory drift limits and prescribed seismic hazard levels associated with predefined nonexceedance probabilities. To verify that design requirements were met, a series of nonlinear time-history analyses NLTHAs was performed using suits of both far-field and near-fault ground motion records. The distributions of interstory drifts obtained from the NLTHA confirm that the Capstone Building designed using DDD meets all four target performance expectations, thereby validating the DDD procedure. Additionally, collapse analysis in accordance with the recently proposed Applied Technology Council project 63 ATC-63 methodology was performed. The results of incremental dynamic analyses confirmed that the Capstone Building designed using the DDD procedure has adequate capacity margin against collapse, as dictated by the ATC-63 methodology.

Experimental Seismic Response of a Full-Scale Light-Frame Wood Building

A full-scale, two-story, light-frame wood townhouse building, designed according to modern U.S. engineered seismic design requirements, was tested on two triaxial shake tables operating in unison. The main objective of this experimental study was to determine the dynamic characteristics and the seismic performance of the test building under various base input intensities, representative of both ordinary and near-field ground motions in southern California. The building was tested with and without interior (gypsum wallboard) and exterior (stucco) wall finishes. The test results revealed that the installation of gypsum wallboard to the interior surfaces of structural wood sheathed walls substantially improved the seismic response of the test building. The application of exterior stucco further improved the seismic response of the test building, particularly in its longitudinal direction, where the shear response of low aspect ratio wall piers dominated. These shake table test results provide the evidence of...

Collapse Fragility of Steel Structures Subjected to Earthquake Mainshock-Aftershock Sequences

AbstractThis paper investigates the collapse probability of mainshock-damaged steel buildings in aftershocks, as an essential part of developing a framework to integrate aftershock seismic hazard into performance-based engineering (PBE). Analytical studies were conducted utilizing structural degradation models derived from existing publicly available NEEShub data. During earthquake events, aftershocks have the potential to cause severe damage to buildings and threaten life safety even when only minor damage is present from the mainshock. While aftershocks are normally somewhat smaller in magnitude, their ground motion intensity is not always smaller. Aftershocks may have a higher peak ground acceleration than the mainshock, even longer duration, and significantly different energy content as a result of the change in their location relative to the site. To date, the description of seismic hazard in PBE has not included the probability of aftershocks. In this study, the structural degradation model of a fou...

Dual-Objective-Based Tornado Design Philosophy

AbstractTornadoes represent a unique natural hazard because of the very low probability of occurrence, short warning times (on the order of only a few minutes), and the intense and destructive forces imposed on engineered and nonengineered buildings. The very low-probability/very high-consequence nature of a tornado strike makes designing for survival and reducing damage under typical financial constraints a substantial challenge. On April 27, 2011, an enhanced Fujita (EF) 4 (EF4) tornado devastated an almost 10-km (5.9-mi) long, 0.8-km-wide (1/2-mi-wide) path, through the city of Tuscaloosa, Alabama, and continued on the ground for 130 km (80 mi). This paper presents the design concept that resulted following a week-long data reconnaissance deployment throughout the city of Tuscaloosa by the authors. The dual-objective philosophy proposed herein is intended to focus on both building damage and loss reduction in low-to-moderate tornado wind speeds and building occupant life safety in more damaging wind-sp...

Making the Case for Improved Structural Design: Tornado Outbreaks of 2011

A total of 1,625 tornadoes occurred in the United States in 2011, resulting in economic losses that exceeded

Approximate R-Factor for Cross-Laminated Timber Walls in Multistory Buildings

25 billion. Two tornado outbreaks stand out because they caused more than half of those losses. The tornadoes that cut through Tuscaloosa, Alabama, on April 27 and Joplin, Missouri, on May 22 were responsible for a combined 223 fatalities and more than 13,000 damaged buildings in the two cities. Although the economic losses associated with tornado damage are well documented, the writers argue that the overall impact should encompass longer term, broader considerations such as the social dis- ruption and psychological effects that impact communities. This paper examines observations by tornado damage assessment teams led by the first author in these two medium-sized cities and suggests that the evolution of building codes and past approaches to construction have led to conditions that made this extent of damage possible. The authors outline a multidisci- plinary path forward that incorporates engineering research and social and economic studies into a new design paradigm leading to building code changes and social practices that will improve resistance and mitigate future losses at a community level from tornadoes.

Three-Dimensional Seismic Response of a Full-Scale Light-Frame Wood Building: Numerical Study

AbstractCross-laminated timber (CLT) is a wood construction technology that has been utilized in Europe for several decades and has become even more popular recently. Although the technology has been in existence for approximately 20 years, its seismic performance has been explored only recently by a handful of researchers. Interest in bringing CLT to the North American construction market necessitates a full understanding of the seismic behavior of CLT systems and the development of a response-modification factor, known as the R-factor, for use in force-based seismic design codes. In this paper, a nonlinear, load-resistance model for CLT shear walls is developed based on reversed-cyclic test data and explained. An estimation of a possible R-factor is obtained by developing a design for a 6-story CLT apartment building, based on computed peak interstory drifts, to achieve good performance in a high seismic region of the United States. It is concluded that using the equivalent lateral force procedure with ...

Quantitative Insight into Rational Tornado Design Wind Speeds for Residential Wood-Frame Structures Using Fragility Approach

The experimental seismic responses of a full-scale two-story light-frame wood townhouse building, designed to modern U.S. engineered seismic design requirements, were compared against the predictions of a new software package entitled seismic analysis package for woodframe structures (SAPWood) developed recently within the NEESWood Project. The main objective of this paper was to verify the accuracy of the predictions from the SAPWood model, which incorporates shear deformations of shear walls as well as cumulative floor displacements caused by the out-of-plane rotations of the floor and ceiling diaphragms. A comparison was conducted on interstory drifts and shear wall deformations for various structural configurations (construction phases) of the test building and excitation levels. Good agreement was found between the numerical predictions and test results for the four different construction phases. The SAPWood model was shown to be a promising numerical tool for predicting the seismic response of light...

Evaluation of Tsunami Loads on Wood-Frame Walls at Full Scale

AbstractTornadoes are an extremely devastating natural hazard that have significant consequences but are currently not considered in the structural design codes due to their low probability of occurrence. These low-occurrence high-consequence events have been studied but not to the extent of other natural hazards. This paper presents the results of a study whose objective was to provide quantitative insight into a rational design wind speed for tornadoes considering the current state-of-practice in construction methods. Five archetype buildings were selected to be representative of the typical residential structure design space in tornado-prone regions of the United States. Wind analysis was performed using the ASCE standard loading in combination with modification factors for tornadic winds developed from the available literature. Fragilities were developed for the main components along the vertical load path that included roof sheathing and roof-to-wall connection. Then, system fragilities for the combi...