Seismic design and testing of buckling‐restrained braces with a thin profile          下载免费PDF全文

Pao‐Chun Lin  Keh‐Chyuan Tsai  Chieh‐An Chang  Yu‐Yun Hsiao  An‐Chien Wu 《地震工程与结构动力学》2016,45(3):339-358

A thin‐profile buckling‐restrained brace (thin‐BRB) consists of a rectangular steel casing and a flat steel core that is parallel to a gusset plate. A thin configuration reduces the width of the restraining member and thus saves usable space in buildings. However, deformable debonding layers, which cover the steel core plate in order to mitigate the difference between the peak tensile and compressive axial forces, provide a space for the steel core to form high mode buckling waves when the thin‐BRB is under compression. The wave crests squeeze the debonding layers and produce outward forces on the inner surface of the restraining member. If the restraining member is too weak in sustaining the outward forces, local bulging failure occurs and the thin‐BRB loses its compression capacity immediately. In order to investigate local bulging behavior, a total of 22 thin‐BRB specimens with a ratio of steel core plate to restraining steel tube depth ranging from 0.3 to 0.7 and axial yield force capacities ranging from 421 kN to 3036 kN were tested by applying either cyclically increasing, decreasing, or constant axial strains. The restraining steel tube widths of all the specimens were smaller than 200 mm and were infilled with mortar with a compressive strength of 97 MPa or 55 MPa. Thirteen of the 22 thin‐BRB specimens' restraining members bulged out when the compressive core strains exceeded 0.03. A seismic design method of the thin‐BRB in preventing local bulging failure is proposed in this study. Test and finite element model (FEM) analysis results suggest that the outward forces can be estimated according to the BRB compressive strength, steel core high mode buckling wavelength, and the debonding layer thickness. In addition, the capacity of the restraining member in resisting the outward forces can be estimated by using the upper bound theory in plastic analysis. Both the FEM analysis and test results indicate that the proposed method is effective in predicting the possibility of local bulging failure. Test results indicate that the proposed design method is conservative for thin‐BRB specimens with a large steel core plate to restraining steel tube depth ratio. This paper concludes with design recommendations for thin‐BRBs for severe seismic services. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

A Hierarchical Bayesian Model Averaging Framework for Groundwater Prediction under Uncertainty          下载免费PDF全文

Nima Chitsazan  Frank T.‐C. Tsai 《Ground water》2015,53(2):305-316

Groundwater prediction models are subjected to various sources of uncertainty. This study introduces a hierarchical Bayesian model averaging (HBMA) method to segregate and prioritize sources of uncertainty in a hierarchical structure and conduct BMA for concentration prediction. A BMA tree of models is developed to understand the impact of individual sources of uncertainty and uncertainty propagation to model predictions. HBMA evaluates the relative importance of different modeling propositions at each level in the BMA tree of model weights. The HBMA method is applied to chloride concentration prediction for the “1,500‐foot” sand of the Baton Rouge area, Louisiana from 2005 to 2029. The groundwater head data from 1990 to 2004 is used for model calibration. Four sources of uncertainty are considered and resulted in 180 flow and transport models for concentration prediction. The results show that prediction variances of concentration from uncertain model elements are much higher than the prediction variance from uncertain model parameters. The HBMA method is able to quantify the contributions of individual sources of uncertainty to the total uncertainty.  相似文献   

Comparison of web plate numerical models for self‐centering steel plate shear walls          下载免费PDF全文

Patricia M. Clayton  Ching‐Yi Tsai  Jeffrey W. Berman  Laura N. Lowes 《地震工程与结构动力学》2015,44(12):2093-2110

Previous research has shown that self‐centering steel plate shear walls (SC‐SPSWs) are capable of achieving enhanced seismic performance at multiple hazard levels, including recentering following design‐level earthquakes. When modeling SC‐SPSWs numerically, these studies considered an idealized tension‐only steel plate shear wall (SPSW) web plate behavior. Research has shown that web plate behavior is more complex than predicted by the idealized model, and web plates can provide more strength, stiffness, and energy dissipation than predicted by the idealized model. The idealized model of web plate behavior is used widely in SPSW numerical models where the moment‐resisting boundary frame provides supplemental hysteretic damping and stiffness; however, in SC‐SPSWs, where the post‐tensioned boundary frame is designed to remain elastic during an earthquake, accounting for the more complex web plate behavior can have a significant impact on seismic performance estimates from numerical simulation. This paper presents different methods for modeling SC‐SPSWs. Responses from these models are compared with experimental results. A simple modification of the tension‐only model, referred to as the tension‐compression strip model, is shown to provide a reasonable approximation of SC‐SPSW behavior. Results from nonlinear response history analyses of SC‐SPSWs with the tension‐only and tension‐compression web plate models are compared to assess how the approximation of web plate behavior affects SC‐SPSW seismic performance. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Seismic design and testing of the bottom vertical boundary elements in steel plate shear walls. Part 1: design methodology          下载免费PDF全文

Keh‐Chyuan Tsai  Chao‐Hsien Li  Hung‐Chi Lee 《地震工程与结构动力学》2014,43(15):2237-2259

This research investigates the seismic design method and the cyclic inelastic behavior of the bottom column, also called the vertical boundary element (VBE), in steel plate shear walls (SPSWs). This study consists of two parts. This Part 1 paper discusses the anticipated pushover responses for properly designed SPSWs and the possible inelastic responses of the bottom VBE at various levels of inter‐story drift. Considering both the tension field action of the infill panel and the sway action of the boundary frame, this study develops a simplified method to compute the flexural and shear demands in the bottom VBE. Based on the superposition method, this approach considers various plastic hinge forming locations at different levels of inter‐story drift. One of the key performance‐based design objectives is to ensure that the top ends of the bottom VBEs remain elastic when the SPSWs are subjected to the maximum considered earthquake. This paper presents the comprehensive design procedures for the bottom VBE. Furthermore, this study conducted cyclic performance evaluation tests of three full‐scale two‐story SPSWs at the Taiwan National Center for Research on Earthquake Engineering in 2011 to validate the effectiveness of the proposed design methods. The experimental program, cyclic inelastic responses of the SPSWs and bottom VBEs, and numerical simulations are presented in Part 2. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Viscosity effect on consolidation of poroelastic soil due to groundwater table depression     

Tung-Lin Tsai 《Environmental Geology》2009,57(5):1055-1064

In this study, the viscosity effect on consolidation of poroelastic soil due to groundwater table depression is examined. A viscoelastic consolidation numerical model is developed to conduct this examination. By nondimensionalizing the governing equations the viscosity number that depends on hydraulic conductivity, viscous moduli, and thickness of soil is obtained to represent the viscosity effect on consolidation of poroelastic soil. The case of clay stratum sandwiched between sandy strata subjected to sudden and gradual groundwater table depressions is used to investigate the importance of viscosity effect to poroelastic consolidation. The results show that the displacement and pore water pressure of clay stratum are strongly related to the viscosity effect. The overestimation of soil displacement will occur if the viscosity effect is neglected. Hence, the viscosity effect needs to be considered in modeling consolidation of poroelastic soil under groundwater table depression.  相似文献   

Earthquake response analyses of a full‐scale five‐story steel frame equipped with two types of dampers     

Yi‐Jer Yu  Keh‐Chyuan Tsai  Chao‐Hsien Li  Yuan‐Tao Weng  Ching‐Yi Tsai 《地震工程与结构动力学》2013,42(9):1301-1320

The seismic performance tests of a full‐scale five‐story passively controlled steel building were conducted on the E‐Defense shaking table in Japan in March 2009. Before the tests, a blind prediction contest was held to allow researchers and practitioners from all over the world to construct analytical models and predict the dynamic responses of the steel frame specimen equipped with buckling‐restrained braces (BRBs) or viscous dampers (VDs). This paper presents the details of two refined prediction models made and results obtained before the tests. When the proposed analytical modeling techniques are adopted as in the two refined prediction models, the overall prediction accuracy is about 90%. Sensitivity studies conducted after the tests are also presented in this paper. The effects of varying each modeling feature on the response simulation accuracy have been investigated. The analytical results suggest that considering concrete full‐composite actions for beam members could improve prediction accuracy by about 20% against using the simplified bare steel beam model. Adopting refined BRB stiffness computed from incorporating finite‐element gusset stiffness only improves the overall prediction accuracy by 0.9%. Considering the BRB dynamic loading test results for analytical BRB strength reduces the error by 1.9%. For the VD frame, incorporating the brace and VD stiffness could improve the overall prediction accuracy by about 15%. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Modeling the sediment yield from landslides in the Shihmen Reservoir watershed,Taiwan     

Zong‐Xian Tsai  Gene J.‐Y. You  Hong‐Yuan Lee  Yu‐Jia Chiu 《地球表面变化过程与地形》2013,38(7):661-674

Landslides generate enormous volumes of sediment in mountainous watersheds; however, quantifying the downstream transport of landslide‐derived sediment remains a challenge. Landslide erosion and sediment delivery to the Shihmen Reservoir watershed in Taiwan was estimated using empirical landslide frequency–area and volume–area relationships, empirical landslide runout models, and the Hydrological Simulation Program‐ FORTRAN (HSPF). Landslide erosion rates ranged from 0.4 mm yr^‐1 to 2.2 mm yr^‐1 during the period 1986–2003, but increased to 7.9 mm yr^‐1 following Typhoon Aere in 2004. The percentage of landslide sediment delivered to streams decreased from 78% during the period 1986–1997 to 55% in 2004. Although the delivery ratio was lower, the volume of landslide sediment delivered to streams was 2.81 × 10⁶ Mg yr^‐1 in 1986–1997 and 8.60 × 10⁶ Mg yr^‐1 in 2004. Model simulations indicate that only a small proportion of the landslide material was delivered downstream. An average of 13% of the landslide material delivered to rivers was moved downstream during the period 1986–1997. In 2004, the period including Typhoon Aere, the annual fluvial sediment yield accounted for approximately 23% of the landslide material delivered to streams. In general, the transfer of sediment in the fluvial system in the Shihmen Reservoir watershed is dominantly transport limited. The imbalance between sediment supply and transport capacity has resulted in a considerable quantity of landslide material remaining in the upper‐stream regions of the watershed. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Application of the TaiWan Ionospheric Model to single-frequency ionospheric delay corrections for GPS positioning   总被引：2，自引：2，他引：0  

Ernest Pagaran Macalalad  Lung-Chih Tsai  Joz Wu  Chao-Han Liu 《GPS Solutions》2013,17(3):337-346

The performance of a three-dimensional ionospheric electron density model derived from FormoSat3/COSMIC GPS Radio Occultation measurements, called the TaiWan Ionosphere Model (TWIM), in removing the ionospheric delays in single-frequency pseudorange observations is presented. Positioning results using TWIM have been compared with positioning results using other ionospheric models, such as the Klobuchar (KLOB) and the global ionospheric model (GIM). C/A code pseudoranges have been observed at three International GPS Service reference stations that are representative of mid-latitude (BOR1 and IRKJ) and low-latitude (TWTF) regions of the ionosphere. The observations took place during 27 geomagnetically quiet days from April 2010 to October 2011. We perform separate solutions using the TWIM, KLOB, GIM ionospheric models and carry out a solution applying no ionospheric correction at all. We compute the daily mean horizontal errors (DMEAN) and the daily RMS (DRMS) for these solutions with respect to the published reference station coordinates. It has demonstrated that TEC maps generate using the TWIM exhibit a detailed structure of the ionosphere, particularly at low-latitude region, whereas the Klobuchar and the GIM only provide the basic diurnal and geographic features of the ionosphere. Also, it is shown that even for lower satellite elevations, the TWIM provides better positioning than the Klobuchar and GIM models. Specifically, using TWIM, the difference of the uncorrected solution (no ionospheric correction), and the other solutions, relative to the uncorrected solution, is 45 % for the mean horizontal error (DMEAN) and 42 % for the horizontal root-mean-square error (DRMS). Using Klobuchar and GIM, the percent for DMEAN only reaches to about 12 % and 3 %, while the values for the DRMS are only 12 and 4 %, respectively. In the vertical direction, all models have a percentage of about 99 and 70 % for the mean vertical error (VMEAN) and vertical root-mean-square error (VRMS), respectively. These percentages show the greater impact of TWIM on the ionospheric correction compared to the other models. In at least 40 % of the observed days and across all stations, TWIM has the smallest DMEAN, VMEAN, DRMS, and VRMS daily values. These values reach 100 % at station TWTF. This shows the overall performance of TWIM is better than the Klobuchar and GIM.  相似文献   

The impacts of natural hazards on Taiwan’s tourism industry     

Hsien-Tang Tsai  Cheng-Jui Tseng  Shian-Yang Tzeng  Tung-Ju Wu  Jen-der Day 《Natural Hazards》2012,62(1):83-91

Typhoon Morakot hit Taiwan in 2009, severely damaging the Alishan National Forest Recreation Area, a famous tourist resort in Taiwan. The only highway to this area was under repair for 10 months after the typhoon. Consequently, Alishan’s tourism industry suffered losses estimated at NT$1 billion. This work investigates the impacts of natural hazards on Taiwan’s tourism industry. First, government, university, and industry experts were invited to a focus-group interview to update criteria for tourism development in Taiwan. Next, the Analytic Hierarchy Process (AHP) was applied to rank the proposed criteria. Last, two tourist attractions, one urban and one rural, are discussed in detail. This work proposes three novel dimensions for Taiwan’s tourism development—destination attraction, destination arrangement, and contingency planning for natural hazards—which comprise nine criteria. Analytical results will provide Taiwan’s tourism industry with references for future policy-making and sustainable development.  相似文献   

A hydrochemical study of Hungtsaiping landslide area, Nantou, Taiwan     

Pei-Ying Lin  Louis Loung-Yie Tsai 《Environmental Earth Sciences》2012,67(4):1045-1060

The Hungtsaiping landslide was triggered by the Chi-Chi earthquake (Mw?=?7.6), which occurred on September 20, 1999 near the town of Chi-Chi in Nantou County in central Taiwan. The purpose of this study is to understand the relationship between geochemical characteristics and the landslide in the Hungtsaiping area. Water samples were collected from springs, creeks, ponds, groundwater and the Yonglu stream once every month from May 2008 to May 2009. Oxygen and hydrogen stable isotopes, ionic concentrations, electrical conductivities, and pH values were analyzed. The results show that the ionic concentrations display a significant spatial variation. For instance, calcium and magnesium bicarbonate-rich water was found on the top and the middle part of the slope. In addition, sodium bicarbonate-rich water with exceptionally high sulfate concentration was found on the foot of the slope. The sulfate content decreased with increasing elevation along the slope. Finally, a conceptual model was established by summarizing the hydrogeochemical analyses. After a scientific understanding of the mechanism of the Hungtsaiping landslide, all of the analytical information can be integrated for hazard prevention in the future.  相似文献