Rehabilitation of a 1985 Steel Moment-Frame Building

2003 ◽  
Vol 19 (2) ◽  
pp. 385-397 ◽  
Author(s):  
Gregg Haskell
Keyword(s):  
San Francisco ◽  
Time History ◽  
Response Spectra ◽  
Nonlinear Time History Analysis ◽  
Elastic Behavior ◽  
Moment Frame ◽  
Earthquake Excitation ◽  
Steel Moment Frame ◽  
Moment Connection ◽  
Frame Building

A 1985 steel moment frame is seismically upgraded using passive energy dissipation, without adding stiffness to the system. The design and analysis techniques for sizing the Velocity Braces™ and their impact on the demand capacity ratios are reviewed. The structure was built in the San Francisco Bay Area in compliance with the 1985 Uniform Building Code (UBC). The moment frame contains the classic pre-Northridge nonductile moment connection, complete with weld backup bars left attached. Nonlinear time-history analysis procedures were implemented to verify the demand capacity ratios at the critical beam-column connections. Flexural demand capacity ratios of .6 achieve elastic behavior in the design basis earthquake with R=1.0. The response spectra of the time history chosen for design exceed the requirements of the 1997 UBC Zone 4. Torsional response to earthquake excitation is minimized by strategic placement of nonlinear viscous dampers. Nonlinear dampers that reduce the flexural demand on joints and control interstory drift without inelastic excursions of the beam flanges are achieved. Floor spectral accelerations and maximum drift limits are reduced to be consistent with immediate occupancy performance. The damper driver mechanism, being velocity driven, reduces moment frame demands and allows flexibility in configuration.

scholarly journals Seismic Performance of a Green Roof Structure

2021 ◽  
Vol 13 (8) ◽  
pp. 4278
Author(s):  
Svetlana Tam ◽  
Jenna Wong
Keyword(s):  
Green Roof ◽  
Time History ◽  
Green Roofs ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Roof Structure ◽  
Nonlinear Time History Analyses ◽  
Vegetated Roofs ◽  
Nonlinear Time History ◽  
The Impact

Sustainability addresses the need to reduce the structure’s impact on the environment but does not reduce the environment’s impact on the structure. To explore this relationship, this study focuses on quantifying the impact of green roofs or vegetated roofs on seismic responses such as story displacements, interstory drifts, and floor level accelerations. Using an archetype three-story steel moment frame, nonlinear time history analyses are conducted in OpenSees for a shallow and deep green roof using a suite of ground motions from various distances from the fault to identify key trends and sensitivities in response.

Effect of bidirectional excitation on seismic performance of regular RC frame buildings designed for modern codes

2021 ◽  
pp. 875529302110478
Author(s):  
Payal Gwalani ◽  
Yogendra Singh ◽  
Humberto Varum
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Inelastic Behavior ◽  
Moment Frame ◽  
Frame Buildings ◽  
Bidirectional Excitation ◽  
Rc Frame Buildings ◽  
Nonlinear Time History ◽  
Hinge Model

The existing practice to estimate seismic performance of a regular building is to carry out nonlinear time history analysis using two-dimensional models subjected to unidirectional excitations, even though the multiple components of ground motion can affect the seismic response, significantly. During seismic shaking, columns are invariably subjected to bending in two orthogonal vertical planes, which leads to a complex interaction of axial force with the biaxial bending moments. This article compares the seismic performance of regular and symmetric RC moment frame buildings for unidirectional and bidirectional ground motions. The buildings are designed and detailed according to the Indian codes, which are at par with the other modern seismic codes. A fiber-hinge model, duly calibrated with the biaxial experimental results, is utilized to simulate the inelastic behavior of columns under bidirectional bending. A comparison of the estimated seismic collapse capacity is presented, illustrating the importance of considering the bidirectional effects. The results from fragility analysis indicate that the failure probabilities of buildings under the bidirectional excitation are significantly higher as compared to those obtained under the unidirectional excitation.

Investigation of Damages in RC Frames Under Near Field Earthquakes Using a Damage Index

2016 ◽  
Vol 16 (02) ◽  
pp. 1450094 ◽  
Author(s):  
Seyed Morteza Zinati Yazdi ◽  
Mohammad Taghi Kazemi
Keyword(s):  
Near Field ◽  
Damage Index ◽  
Time History ◽  
General Rule ◽  
Nonlinear Time History Analysis ◽  
Far Field ◽  
Moment Frames ◽  
Moment Frame ◽  
Rc Frames ◽  
Nonlinear Time History

Heavy damages on structures caused by near field earthquakes in recent years has brought serious attention to this problem. An examination of previous records has shown significant differences for near field earthquakes, including a large energy pulse, unlike far field earthquakes. But as a general rule, the effects of near field earthquakes have been ignored in most building codes. The purpose of this paper is to investigate the effect of near field earthquakes on reinforced concrete (RC) moment frames. To achieve this goal, the Erduran damage index, an efficient way to calculate damage, was employed to analyze two 4- and 8-story RC moment frame buildings. The buildings with moderate and high ductility were designed by the strength criteria. Seven pairs of near field and far field earthquakes were scaled and used for dynamic nonlinear time history analysis. Using Erduran’s beam and column damage index, respectively, based on rotation and drift, the results from both near and far field earthquakes were compared. Moreover, for better assessment, 4-story buildings were evaluated from the performance based viewpoint of design. We observe from the results that most of the components of the structures under near field earthquakes sustained severe damages and in some cases even component failure. Components of the structures under near field earthquakes suffered from 30% more of damage, on average, than that under far field earthquakes.

Project Specifications for New Steel Moment-Frame Building Construction

2003 ◽  
Vol 19 (2) ◽  
pp. 309-315
Author(s):  
Robert E. Shaw
Keyword(s):  
Quality Assurance ◽  
Building Construction ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Writing Project ◽  
Frame Building ◽  
Industry Standards ◽  
Frame Buildings ◽  
Frame Construction ◽  
New Industry

FEMA-353, Recommended Specifications and Quality Assurance Guidelines for Steel Moment-Frame Construction for Seismic Applications, contains numerous provisions related to the materials, details, quality, and inspection of steel moment-frame buildings in seismic regions. These provisions continue to evolve as industry standards and practices are reviewed, modified, and adopted to meet the need for good seismic performance. Those writing project specifications must remain current with new industry developments and standards.

ASCE-41 and FEMA-351 Evaluation of E-Defense Collapse Test

2009 ◽  
Vol 25 (4) ◽  
pp. 927-953 ◽  
Author(s):  
Bruce F. Maison ◽  
Kazuhiko Kasai ◽  
Gregory Deierlein
Keyword(s):  
Seismic Evaluation ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Seismic Rehabilitation ◽  
Frame Building ◽  
Weak Beam ◽  
Beam Design ◽  
Safe Side ◽  
Computer Analyses

A welded steel moment-frame building is used to assess performance-based engineering guidelines. The full-scale four-story building was shaken to collapse on the E-Defense shake table in Japan. The collapse mode was a side-sway mechanism in the first story, which occurred in spite of a strong-column and weak-beam design. Computer analyses were conducted to simulate the building response during the experiment. The building was then evaluated using the Seismic Rehabilitation of Existing Buildings (ASCE-41) and Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings (FEMA-351) for the collapse prevention performance level via linear and nonlinear procedures. The guidelines had mixed results regarding the characterization of collapse, and no single approach was superior. They mostly erred on the safe side by predicting collapse at shaking intensities less than that in the experiment. Recommendations are made for guideline improvements.

Shaking Table Test for Base-Isolated Nuclear Island Structure Model

2017 ◽  
Author(s):  
Yang Jie ◽  
Li ShaoPing ◽  
Yuan Fang ◽  
Xia ZuFeng ◽  
Huang XiaoLin
Keyword(s):  
Shaking Table Test ◽  
Three Dimensional ◽  
Time History ◽  
Response Spectra ◽  
Shaking Table ◽  
Nonlinear Time History Analysis ◽  
Earthquake Simulation ◽  
Maximum Displacement ◽  
Island Structure ◽  
Reduced Scale

In this paper, the base-isolated design of Nuclear Island structure will be introduced, including the general requirement and the goal of the base-isolated design. Integrated assessment has been performed for the base-isolated design of Nuclear Island structure in the earthquake 0.6g. A series of nonlinear time-history analysis were performed to predict the maximum displacement and acceleration of the isolation layer, the maximum stress of the isolation units, and the floor response spectra of each story of the superstructure in the earthquake 0.6g, considering the realistic mechanical properties and the layout of the isolators. In order to provide realistic data to validate the numerical method, a reduced-scale earthquake simulation of base-isolated nuclear structure on a shaking table was carried out. The study was primarily focused on the response of superstructure and the isolation unit. The dynamic characteristic was examined, together with the vibration acceleration and displacement under different levels of seismic wave. The test results of a reduced-scale nuclear island model previously tested on a shaking table were compared with three-dimensional finite element simulation results. The results of this study provide the technical basis for the base-isolated design of Nuclear Island structure.

scholarly journals Assembly-Based Vulnerability of Buildings and Its Use in Performance Evaluation

2001 ◽  
Vol 17 (2) ◽  
pp. 291-312 ◽  
Author(s):  
Keith A. Porter ◽  
Anne S. Kiremidjian ◽  
Jeremiah S. LeGrue
Keyword(s):  
Cost Estimation ◽  
Seismic Vulnerability ◽  
Structural Model ◽  
Structural Response ◽  
Time History ◽  
Simulation Approach ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Specific Level

Assembly-based vulnerability (ABV) is a framework for evaluating the seismic vulnerability and performance of buildings on a building-specific basis. It utilizes the damage to individual building components and accounts for the building's seismic setting, structural and nonstructural design and use. A simulation approach to implementing ABV first applies a ground motion time history to a structural model to determine structural response. The response is applied to assembly fragility functions to simulate damage to each structural and nonstructural element in the building, and to its contents. Probabilistic construction cost estimation and scheduling are used to estimate repair cost and loss-of-use duration as random variables. It also provides a framework for accumulating post-earthquake damage observations in a statistically systematic and consistent manner. The framework and simulation approach are novel in that they are fully probabilistic, address damage at a highly detailed and building-specific level, and do not rely extensively on expert opinion. ABV is illustrated using an example pre-Northridge welded-steel-moment-frame office building.

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