Regression Model Evaluation for Highway Bridge Component Deterioration Using National Bridge Inventory Data

Accurate prediction of bridge component condition over time is critical for determining a reliable maintenance, repair, and rehabilitation (MRR) strategy for highway bridges. Based on bridge inspection data, regression models are the most-widely adopted tools used by researchers and state agencies to predict future bridge condition (FHWA 2007). Various regression models can produce quite different results because of the differences in modeling assumptions. The evaluation of model quality can be challenging and sometimes subjective. In this study, an external validation procedure was developed to quantitatively compare the forecasting power of different regression models for highway bridge component deterioration. Several regression models for highway bridge component rating over time were compared using the proposed procedure and a traditional apparent model evaluation method based on the goodness-of-fit to data. The results obtained by applying the two methods are compared and discussed in this paper

Effect of Plan Configuration on Seismic Performance of Single-Story, Wood-Frame Dwellings

A numerical investigation is presented on effects of plan configuration on seismic responses of single-story, wood-frame dwellings. 151 models were developed using observations of 412 dwellings of rectangular, L, T, U, and Z-shapes in Oregon. A nonlinear, time-history program, Seismic Analysis Package for Wood-frame Structures, was the analysis platform. Models were analyzed for 10 pairs of biaxial ground motions (spectral accelerations from 0.1 g to 2.0 g) for Seattle. Configuration comparisons were made using median shear wall maximum drifts and occurrences of maximum drifts exceeding the 3% collapse prevention limit. Plan configuration significantly affects performance through building mass, lateral stiffnesses, and eccentricities. Irregular configuration tends to induce eccentricity and cause one wall to exceed the allowable drift limit, and fail, earlier than others. Square-like buildings usually perform better than long, thin rectangles. Classification of single-story dwellings based on shape parameters, including size and overall aspect ratio, plan shape, and percent cutoff area, can organize a building population into groups having similar performance and be a basis for including plan configuration in rapid visual screening.Keywords: Configuration, Seismic analysis, Wood structure

Effect of Plan Configuration on Seismic Performance of Single-Story Wood-Frame Dwellings

A numerical investigation is presented on effects of plan configuration on seismic responses of single-story, wood-frame dwellings. 151 models were developed using observations of 412 dwellings of rectangular, L, T, U, and Z-shapes in Oregon. A nonlinear, time-history program, Seismic Analysis Package for Wood-frame Structures, was the analysis platform. Models were analyzed for 10 pairs of biaxial ground motions (spectral accelerations from 0.1 g to 2.0 g) for Seattle. Configuration comparisons were made using median shear wall maximum drifts and occurrences of maximum drifts exceeding the 3% collapse prevention limit. Plan configuration significantly affects performance through building mass, lateral stiffnesses, and eccentricities. Irregular configuration tends to induce eccentricity and cause one wall to exceed the allowable drift limit, and fail, earlier than others. Square-like buildings usually perform better than long, thin rectangles. Classification of single-story dwellings based on shape parameters, including size and overall aspect ratio, plan shape, and percent cutoff area, can organize a building population into groups having similar performance and be a basis for including plan configuration in rapid visual screening

A procedure for rapid visual screening for seismic safety of wood-frame dwellings with plan irregularity

This paper highlights the development of a rapid visual screening (RVS) tool to quickly identify, inventory, and rank residential buildings that are potentially seismically hazardous, focusing on single-family, wood-frame dwellings with plan irregularity. The SAPWood software was used to perform a series of nonlinear time-history analyses for 480 representative models, covering different combinations of plan shapes, numbers of floors, base-rectangular areas, shape aspect ratio, area percentage cutoffs, window and door openings, and garage doors. The evolutionary parameter hysteresis model was used to represent the load–displacement relationship of structural panel-sheathed shear walls and a 10 parameter CUREE hysteresis model for gypsum wallboard sheathed walls. Ten pairs of ground motion time histories were used and scaled to four levels of spectral acceleration at 0.167, 0.5, 1.0, and 1.5g. An average seismic performance grade for each model was generated based on the predicted maximum shear wall drifts. Five seismic performance grades: 4, 3, 2, 1, and 0, are associated with the 1% immediate occupancy drift limit, 2% life safety limit, 3% collapse prevention limit, 10% drift, and exceeding 10% drift, respectively. The obtained average seismic performance grades were used to develop a new RVS tool that is applicable for checking the seismic performance of either existing or newly designed single-family, wood-frame dwellings. It examines the adequacy of the structure’s exterior shear walls to resist lateral forces resulting from ground motions, including torsional forces induced from plan irregularity

Damage Assessment of a Full-Scale Six-Story Wood-Frame Building Following Triaxial Shake Table Tests

In the summer of 2009, a full-scale midrise wood-frame building was tested under a series of simulated earthquakes on the world’s largest shake table in Miki City, Japan. The objective of this series of tests was to validate a performance-based seismic design approach by qualitatively and quantitatively examining the building’s seismic performance in terms of response kinematics and observed damage. This paper presents the results of detailed damage inspections following each test in a series of five shake table tests, and explains their qualitative synthesis to provide design method validation. The seismic test program had two phases. Phase I was the testing of a seven-story mixed-use building with the first story consisting of a steel special moment frame (SMF) and stories 2–7 made of light-frame wood. In Phase II, the SMF was heavily braced such that it effectively became an extension of the shake table and testing was conducted on only stories 2–7, making the building a six-story light-frame multifamily residential building instead of a mixed-use building. All earthquake motions were scalings of the 1994 Northridge earthquake at the Canoga Park recording station with seismic intensities ranging from peak ground accelerations of 0.22 to 0.88 g. The building performed quite well during all earthquakes with damage only to the gypsum wall board (drywall), no sill plate splitting, no nails withdrawing or pulling through the sheathing, no edge tearing of the sheathing, no visible stud splitting around tie-down rods, and reasonable floor accelerations. On the basis of damage inspection, it was concluded that it is possible to design this type of building and keep the damage to a manageable level during major earthquakes by utilizing the new design approach

Damage Assessment of a Full-Scale Six-Story Wood-Frame Building Following Triaxial Shake Table Tests

In the summer of 2009, a full-scale midrise wood-frame building was tested under a series of simulated earthquakes on the world's largest shake table in Miki City, Japan. The objective of this series of tests was to validate a performance-based seismic design approach by qualitatively and quantitatively examining the building's seismic performance in terms of response kinematics and observed damage. This paper presents the results of detailed damage inspections following each test in a series of five shake table tests, and explains their qualitative synthesis to provide design method validation. The seismic test program had two phases. Phase I was the testing of a seven-story mixed-use building with the first story consisting of a steel special moment frame (SMF) and stories 2-7 made of light-frame wood. In Phase II, the SMF was heavily braced such that it effectively became an extension of the shake table and testing was conducted on only stories 2-7, making the building a six-story light-frame multifamily residential building instead of a mixed-use building. All earthquake motions were scalings of the 1994 Northridge earthquake at the Canoga Park recording station with seismic intensities ranging from peak ground accelerations of 0.22 to 0.88 g. The building performed quite well during all earthquakes with damage only to the gypsum wall board (drywall), no sill plate splitting, no nails withdrawing or pulling through the sheathing, no edge tearing of the sheathing, no visible stud splitting around tie-down rods, and reasonable floor accelerations. On the basis of damage inspection, it was concluded that it is possible to design this type of building and keep the damage to a manageable level during major earthquakes by utilizing the new design approach. DOI: 10.1061/(ASCE)CF.1943-5509.0000202. (C) 2012 American Society of Civil EngineersKeywords: Experimentation, Shake table tests, Damage assessment, Wood structures, Performance, Full-scale tests, Damage, Full-scale experiment, Earthquakes, Multi-story buildings, Shake tabl

Numerical modeling of CLT diaphragms tested on a shake-table experiment

Current standards and existing literature provide very limited information regarding the design of cross-laminated timber (CLT) floor diaphragms. In addition, limited procedures exist to develop analytical models to estimate the deformation response of CLT floor diaphragms. This paper presents a modelling approach that captures the response of CLT timber diaphragms, with a special focus on CLT spline panel-to-panel connections. The modeling approach is validated through the comparison of the results of the computation model with experimental data obtained from a series of shake-tables test performed on a two-story full-scale building tested in the summer of 2017 at UC San Diego Large High Performance Outdoor Shake Table. The two-story building included two diaphragm designs at each floor level. The first solution consists of CLT panels connected with plywood surface splines that are fastened using self-tapping screws, while the second consists of a CLT-concrete composite floor solution. Results from the nonlinear pushover analysis describe accurately the experimental data obtained.(undefined

A Dual-Objective-Based Tornado Design Philosophy

Tornadoes 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 non-engineered 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 EF4 tornado devastated a 0.8 km (1/2 mile) wide path almost 10 km (5.9 miles) long through the city of Tuscaloosa, Alabama continuing on the ground for 130 km (80 miles). 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 windspeeds and building occupant life safety in more damaging wind speed events such as EF4 and EF5 tornadoes. The philosophy articulates a design methodology that is the basis upon which structural engineering was formed, namely provide life safety and control damage, but focused at separate tornado intensity levels.Keywords: Residential building, Design method, Natural hazard, TornadoKeywords: Residential building, Design method, Natural hazard, Tornad

Dual-Objective-Based Tornado Design Philosophy

Tornadoes 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-speed events such as EF4 and EF5 tornadoes. The philosophy articulates a design methodology that is the basis upon which structural engineering was formed—namely, provide life safety and control damage—but the new philosophy is focused at separate tornado intensity levels