Seismic design and test of gusset connections for buckling‐restrained braced frames          下载免费PDF全文

Pao‐Chun Lin  Keh‐Chyuan Tsai  An‐Chien Wu  Ming‐Chieh Chuang 《地震工程与结构动力学》2014,43(4):565-587

The corner gusset plates in a steel braced frame can be subjected to forces not only from the brace but also from the effects of the frame actions. In this study, several finite element models are constructed to analyze the gusset‐to‐beam and gusset‐to‐column interface forces. It is found that the frame actions affect the gusset interface force distributions significantly. A simplified strut model to represent the gusset plate is adopted to evaluate the frame action forces. In addition, the generalized uniform force method is adopted as it provides more freedom for designers to configure the gusset plate shapes than using the uniform force method. In this paper, a performance‐based design method is proposed. The gusset interface force demands take into account the combined effect of the brace maximum axial force capacity and the peak beam shear possibly developed in the frame. The specimen design and key results of a series of full‐scale three‐story buckling‐restrained braced frame (BRBF) hybrid tests are discussed. The gusset interface cracks observed at inter‐story drift greater than 0.03 radians can be well predicted by using the proposed design method. The BRBF tests and analyses confirm that the proposed design method is reasonable. The effectiveness of varying the width of gusset edge stiffeners in reducing the gusset tip stress concentrations is also investigated. This paper concludes with recommendations for the seismic design of BRBF corner gusset plates. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Welded end‐slot connection and debonding layers for buckling‐restrained braces          下载免费PDF全文

Keh‐Chyuan Tsai  An‐Chien Wu  Chih‐Yu Wei  Pao‐Chun Lin  Ming‐Chieh Chuang  Yi‐Jer Yu 《地震工程与结构动力学》2014,43(12):1785-1807

The debonding mechanism has a significant effect on the performance of a buckling‐restrained brace (BRB). In this paper, a method for estimating the compression strength adjustment factor for any given BRB core strain is presented. Experimental investigations were conducted on four BRBs to examine the efficiency of four different debonding materials in reducing the difference between the cyclic peak compression and tension. Test results indicate that chloroprene rubber is very easy to install and very effective in minimizing the difference between the compressive and tensile capacities. The excellent performance of 13 full‐scale welded end‐slot BRBs (WES‐BRBs) is illustrated through experiments. Cyclic loading test results of a 12.5‐m long jumbo WES‐BRB reveal that its peak compressive strength exceeds 16,800 kN and its maximum core strain reaches 0.035. All WES‐BRBs show satisfactory performance with a very stable hysteresis response, modest peak compressive to tensile strength ratio, and very predictable axial stiffness. These specimens sustain a cumulative plastic deformation of greater than 400 times the yield deformation. The hysteresis responses can be satisfactorily predicted by using a two‐surface plasticity analytical model. Advantages of the welded end‐slot connections are also presented through a discussion on the effects of the BRB yield region length ratio on the effective stiffness, the yield story drift, and the core strain level. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

An Analysis of Reducing Perchloroethylene Emissions in the Urban Environment: A Case Study of Taiwan     

Wen‐Tien Tsai 《洁净——土壤、空气、水》2012,40(2):123-126

Selected volatile organic compounds (VOCs) emitted from commercial activities and industrial processes have been classified as hazardous air pollutants, posing a potential health risk in the urban environment. In this respect, perchloroethylene (PCE), a suspected human carcinogen, is the most noticeable compound because it is widely used in laundries and hotels as a dry‐cleaning solvent. The objective of this paper was to quantify the emissions of PCE and other petroleum‐based solvents from dry cleaning business in illustration of the regulatory infrastructure of reducing PCE exposure in the environment of Taiwan. Based on the Emission Factors (AP‐42) method, the emissions of the non‐methane hydrocarbons (NMHCs) from dry cleaning business had decreased from 5100 metric tons in 1997 to 2800 metric tons in 2007. The success of significant reduction of NMHCs in Taiwan has been ascribed to the fact that Taiwan established the relevant regulations at the end of the 1990s. From the data on the industrial/commercial demand for PCE and the emission inventories of NMHCs from dry cleaning business, the reduction of PCE emissions will show a declining trend in the near future.  相似文献   

Characteristics of the outer rise seaward of the Manila Trench and implications in Taiwan–Luzon convergent belt, South China Sea     

Jih-Hsin Chang  Ho-Shing Yu  Tung-Yi Lee  Ho-Han Hsu  Char-Shine Liu  You-Tsung Tsai 《Marine Geophysical Researches》2012,33(4):351-367

The outer rise on the distal periphery of a subduction system is caused by emplacement of an accreted load onto the flexed oceanic lithosphere. By examining the bathymetry and free-air gravity anomaly data collected by satellite observations and marine reflection seismic data collected during the TAIGER project, we demonstrate the characteristics of the flexural outer rise seaward of the Manila Trench. The region of the outer rise on the westernmost periphery of the Manila subduction system is characterized by the positive free-air gravity anomaly seaward parallel to the Manila Trench and the morphological rise at the south of the Manila subduction system. A flexure simulation is performed based on the flexural profiles along the southern Manila Trench-outer system and the resulting effective elastic thickness values may provide an alternative aspect for the spreading rates of the South China Sea basin. Since both the western periphery of the Taiwan collision belt and Manila subduction belt are dominated by the strain regime of extension of flexural origin, it appears that the strain regime of flexural extension associated with the flexural forebulge of the Western Taiwan Foreland Basin to the north, and the strain regime of flexural extension associated with the outer rise seaward of the Manila Trench to the south are meridionally interconnected. This revised understanding of the strain regime of flexural extension origin west of the Taiwan–Luzon convergent belt provides an alternative point of view on the strain regime offshore SW Taiwan.  相似文献   

Bayesian Chance‐Constrained Hydraulic Barrier Design under Geological Structure Uncertainty          下载免费PDF全文

Nima Chitsazan  Hai V. Pham  Frank T.‐C. Tsai 《Ground water》2015,53(6):908-919

The groundwater community has widely recognized geological structure uncertainty as a major source of model structure uncertainty. Previous studies in aquifer remediation design, however, rarely discuss the impact of geological structure uncertainty. This study combines chance‐constrained (CC) programming with Bayesian model averaging (BMA) as a BMA‐CC framework to assess the impact of geological structure uncertainty in remediation design. To pursue this goal, the BMA‐CC method is compared with traditional CC programming that only considers model parameter uncertainty. The BMA‐CC method is employed to design a hydraulic barrier to protect public supply wells of the Government St. pump station from salt water intrusion in the “1500‐foot” sand and the “1700‐foot” sand of the Baton Rouge area, southeastern Louisiana. To address geological structure uncertainty, three groundwater models based on three different hydrostratigraphic architectures are developed. The results show that using traditional CC programming overestimates design reliability. The results also show that at least five additional connector wells are needed to achieve more than 90% design reliability level. The total amount of injected water from the connector wells is higher than the total pumpage of the protected public supply wells. While reducing the injection rate can be achieved by reducing the reliability level, the study finds that the hydraulic barrier design to protect the Government St. pump station may not be economically attractive.  相似文献   

Precast concrete wall with end columns (PreWEC) for earthquake resistant design          下载免费PDF全文

Sri Sritharan  Sriram Aaleti  Richard Stuart Henry  Kuang‐Yen Liu  Keh‐Chyuan Tsai 《地震工程与结构动力学》2015,44(12):2075-2092

An innovative seismic resisting system consisting of a Pre cast W all with E nd C olumns (or PreWEC) has been developed, and its performance has been verified using large‐scale cyclic testing. The wall and end columns in the PreWEC system are anchored individually to a foundation using unbonded post‐tensioning. A newly designed, low‐cost mild steel connector is used to connect the wall and end columns horizontally along the vertical joint. The connectors are easily replaceable and provide additional hysteretic energy dissipation to the system. The PreWEC system can be economically designed to have a lateral load carrying capacity similar to that of a comparable reinforced concrete wall, while minimizing damage and providing self‐centering capability. In addition to confirming these benefits, the large‐scale test demonstrated that the PreWEC system: (i) would provide superior seismic performance compared to other currently available structural wall systems especially for the precast industry; and (ii) meets all the mandatory acceptance criteria established by the American Concrete Institute (ACI) for special unbonded post‐tensioned precast structural walls and building frame special reinforced concrete shear wall systems, as defined in the American Concrete Society of Civil Engineers (ASCE) 7‐05. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Seismic design and experiment of single and coupled corner gusset connections in a full‐scale two‐story buckling‐restrained braced frame          下载免费PDF全文

Pao‐Chun Lin  Keh‐Chyuan Tsai  An‐Chien Wu  Ming‐Chieh Chuang  Chao‐Hsien Li  Kung‐Juin Wang 《地震工程与结构动力学》2015,44(13):2177-2198

A gusset plate is subjected to forces induced from a buckling‐restrained brace (BRB) and frame action. In this study, a performance‐based design method of the gusset connections incorporating a BRB and frame actions is investigated. The force demands resulting from the BRB axial force are computed from the generalized uniform force method. The force demands induced from the frame action effects primarily result from beam shear. A conservative method, which considers the beam axial force effect and the thereafter reduced beam flexural capacity possibly developed at the gusset tips, is adopted in estimating the maximum beam shear. An improved equivalent strut model is used to represent the gusset plate subjected to the frame action effect. The total force demands of the gusset connection are combined from the BRB force and the frame actions. For design purposes, the stress distributions on the gusset interfaces are linearized. The maximum von Mises stress combining the normal and shear stresses is considered as the demand for the gusset plate design. In order to verify the effectiveness of the proposed design method, experiments on a two‐story full‐scale buckling‐restrained braced frame (BRBF) were performed. The chevron and single diagonal brace configurations were arranged in the second and the first stories, respectively. Two different corner gusset connection configurations including one single corner gusset and one coupled corner gusset connection, where two braces in adjacent stories joined at the same beam‐to‐column joint, were tested. The BRBF specimen was subjected to cyclically increasing lateral displacements with a maximum frame drift of 0.04 rad. The maximum story drifts reached 0.035 and 0.061 rad. in the first and the second stories, respectively. At the end of the tests, no fractures were observed on any of the gusset interfaces. Along the gusset interfaces, the normal and shear stress distributions computed from the proposed design procedures and the FEM analysis correlated well with the experimental results. This paper concludes with the procedure and recommendations for the performance‐based design of gusset connections. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Critical limit states in seismic buckling‐restrained brace and connection designs          下载免费PDF全文

Ming‐Chieh Chuang  Keh‐Chyuan Tsai  Pao‐Chun Lin  An‐Chien Wu 《地震工程与结构动力学》2015,44(10):1559-1579

A welded end‐slot buckling‐restrained brace (WES‐BRB) has been developed at the Taiwan National Center for Research on Earthquake Engineering (NCREE). A steel frame equipped with a WES‐BRB can offer a cost‐effective solution to meet interstory drift and earthquake‐resistant design requirements for seismic steel buildings. According to the WES‐BRB and connection design procedure proposed by NCREE, there are seven key elements of a buckling‐restrained braced frame (BRBF) design that require design checking. In order to assist an engineer with the design of the WES‐BRB members and connections, an innovative cloud service named Brace on Demand has been constructed at NCREE. In this study, using 581 BRBF design examples, the effectiveness of the proposed design procedures to meet all design checks is demonstrated. It is found that the most critical limit states for an initial design are joint region buckling, gusset plate buckling, and gusset‐to‐beam and gusset‐to‐column interface strength. Accordingly, the causes of improper designs and associated strategies for improving the initial designs are discussed in this paper. Recommendations on initial selections including the BRB joint size and gusset plate thickness are given. The paper provides the detailed road map for engineers to develop the spreadsheet for BRB and connection designs. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

The assessment of high recharge areas using DO indicators and recharge potential analysis: a case study of Taiwan’s Pingtung plain   总被引：2，自引：2，他引：0  

Jui-Pin Tsai  Yu-Wen Chen  Liang-Cheng Chang  Wen-Fu Chen  Chung-Jung Chiang  You-Cheng Chen 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(3):815-832

Identifying high groundwater recharge areas is important for the conservation of groundwater quality and quantity. A common practice used by previous studies is to estimate groundwater recharge potential (GRP) using recharge potential analysis (RPA) under different environments. These studies use the estimated GRP to identify the high potential groundwater recharge sites. However, the RPA parameters are subjectively defined for these previous studies. To remove the supposition, this study proposes a systematic approach that defines the RPA parameter values based on the theory of parameter identification. This study uses dissolved oxygen (DO) indicators to calibrate the RPA parameters. This calibration improves the correlation coefficient between the DO indicators and computed GRP values from 0.63 to 0.87. By comparing the initial values, these results indicate that the estimated RPA parameters better represent the field infiltration characteristic. This result also indicates that defining the RPA parameter values based on DO indicators is necessary and important for accuracy. These calibrated parameters are used to estimate the GRP distribution of Taiwan’s Pingtung Plain. The GRP values are delineated into five levels. High and excellent GRP areas are defined as high recharge areas, which compose about 26.74 % of the study area. Based on the proposed method, the estimated GRP distribution can accurately represent the study area’s field recharge characteristics. These study results can be a good reference for groundwater recharge analyses, specifically if well data is limited or difficult to obtain.  相似文献   

Bidirectional substructure pseudo‐dynamic tests and analysis of a full‐scale two‐story buckling‐restrained braced frame          下载免费PDF全文

Hsen‐Han Khoo  Keh‐Chyuan Tsai  Ching‐Yi Tsai  Cheng‐Yu Tsai  Kung‐Juin Wang 《地震工程与结构动力学》2016,45(7):1085-1107

A two‐story buckling‐restrained brace (BRB) frame was tested under bidirectional in‐plane and out‐of‐plane loading to evaluate the BRB stability and gusset plate design. The test comprised pseudo‐dynamic loadings using the 1999 Chi‐Chi earthquake scaled to the 50%, 10%, and 2% probability of exceedance in 50 years and a cyclic regime of increasing amplitudes of up to 3.0% story drift ratio (SDR). The specimen had a unique configuration where the beams were connected to the columns through shear tabs welded to the column flanges and bolted to the beam webs. Stable hysteretic behavior with only minor cracking at the gusset‐to‐column welds was observed under the pseudo‐dynamic tests, with maximum in‐plane and out‐of‐plane SDRs of 2.24% and 1.47% respectively. Stable behavior continued into the cyclic test where fracture of the gusset‐to‐column welds occurred in the first cycle to simultaneous bidirectional SDR of 3.0%. The observed BRB stability is consistent with a methodology developed for BRB frames under simultaneous in‐plane and out‐of‐plane drifts. The specimen behavior was studied using a finite element model. It was shown that gusset plates are subjected to a combination of BRB force and frame action demands, with the latter increasing the gusset‐to‐beam and gusset‐to‐column interface demands by an average of 69% and 83% respectively. Consistent with the test results, failure at the gusset‐to‐column interfaces is computed when frame action demands are included, thus confirming that not considering frame action demands may results in unconservative gusset plate designs. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献