scholarly journals The effect of number and position of braced frames on column behavior of the dual steel structural system (MRF and EBF) (With a view on amplified seismic load)

2015 ◽  
Vol 37 ◽  
pp. 277
Author(s):  
Sajjad Mohammadi ◽  
Abd-ol-Reza Sarvghad Moghaddam ◽  
Alireza Faroughi
Keyword(s):  
Seismic Design ◽  
Structural Model ◽  
Seismic Load ◽  
Structural System ◽  
Braced Frames ◽  
Moment Frame ◽  
Moment Capacity ◽  
Moment Resisting Frame ◽  
Moment Resisting

In seismic design of structures, determination of number and position of braced frames, considering the architectural scheme of projects, is usually confronted by obstacles. Due to this fact, in some cases, selecting the best location and number of braced bays has led to mistakes in determination of their adjacent members (columns) design loads. One of the seismic design requirements of lateral resisting system is to control the columns adjacent to braced bays for load combinations of amplified seismic load, which is a function of over-strength factor of the structure. This research aims to present and introduce the best structural model of number and position of braced frames in a structural system, such as steel moment resisting frame and eccentric braces dual system; because in 3rd revision of Iranian 2800 standard of seismic provision, there are statements and criteria provided only for capacity of moment frame, not for braces. Though the amplified seismic load function is controlled in models which columns are connected to braces in 2 directions, and seismic loads are applied in those 2 directions, number of damage hinges (Exceeding CP) is significantly increased in comparison to the models with straggly braces. As the increase in axial force of these columns leads to decrease in their moment capacity (despite controlling the amplified seismic load provision), columns in dual systems that resist flexure, would be damaged and exceed the collapse threshold much sooner than other columns. This important fact is not presented in Iranian or even American codes and provisions.

Performance of self-centering steel moment frame considering stress relaxation in prestressed cables

2020 ◽  
Vol 23 (9) ◽  
pp. 1813-1822
Author(s):  
Seyyed Morteza Asadolahi ◽  
Nader Fanaie
Keyword(s):  
Stress Relaxation ◽  
Stress Reduction ◽  
Original Position ◽  
Dissipated Energy ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Moment Resisting Frames ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Over Time

Buildings can be designed to limit the earthquake-induced damage to members that can easily be repaired. Self-centering moment-resisting frames can be used as effective structural systems for this purpose. Self-centering moment-resisting frames with prestressed cables are able to return the structure to its original position after the earthquake. The internal forces in self-centering moment-resisting frames are transferred between the beam and the column by post-tensioned cables. As a main member of self-centering connections, prestressed cables play a significant role in such systems. Cable tension decreases over time due to the effect of stress relaxation on the performance of the system. Stress relaxation is a time-dependent phenomenon causing stress reduction over time in the members prestressed at a constant strain. Therefore, the effect of stress relaxation on the performance of self-centering moment-resisting frames can be significant. In this article, after simulating and validating a moment-resisting frame with self-centering connections, stiffness and moment–rotation hysteresis diagrams were analyzed after 0, 1, 5, 10, and 20 years of cable prestressing. According to the results, two equations were presented to estimate the reduction in the connection stiffness and dissipated energy by the system based on prestressing level and the time after prestressing. The proposed equations could be used to model semi-rigid connections.

Performance of School Buildings in Turkey During the 1999 Düzce and the 2003 Bingöl Earthquakes

2009 ◽  
Vol 25 (2) ◽  
pp. 239-256 ◽  
Author(s):  
Turel Gur ◽  
AliCihan Pay ◽  
Julio A. Ramirez ◽  
Mete A. Sozen ◽  
Arvid M. Johnson ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
School Buildings ◽  
Floor Plan ◽  
Structural System ◽  
Concrete Frames ◽  
Structural Walls ◽  
Concrete Walls ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
The Moment

Several school buildings were surveyed in the disaster areas of the Marmara (17 August 1999, [Formula: see text]), Düzce (12 November 1999, [Formula: see text]), and Bingöl (1 May 2003, [Formula: see text]) earthquakes in Turkey. Among them, 21 reinforced concrete buildings were found to have an identical floor plan. Lateral load resisting structural system consisted of reinforced concrete frames (moment-resisting frame) in 16 of the buildings and structural concrete walls integrated with the moment-resisting frame (dual system) in the remaining five buildings. The number of stories above ground in these buildings ranged from two to four. These school buildings provide a nearly ideal test of the effect of a single important structural characteristic on the performance of buildings with structural designs that are uniform in all other respects. Our observation is that the presence of structural walls improves the behavior of reinforced concrete systems drastically.

EVALUATION OF THE DYNAMIC CHARACTERISTICS FOR SEISMIC DESIGN OF MULTI-STORY BUILDINGS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Aya Aboelhamd ◽  
Aman Mwafy ◽  
Suliman Gargoum
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Building Codes ◽  
Fundamental Period ◽  
Braced Frames ◽  
Data Set ◽  
Structural Dynamic ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Period Data

The fundamental period of vibration is a critical structural dynamic characteristic in seismic design. Several expressions for the calculation of the fundamental period have been recommended by different building codes and previous studies. However, further studies are still needed to evaluate the design expressions used for the calculation of the fundamental periods and assess the need for further refinement. In this study, comprehensive fundamental period data from two sources is collected and compared with different formulas from building codes and previous studies. The first data set is obtained from 147 instrumented buildings with various lateral force resisting systems (LFRSs). The second set of period data are collected from the dynamic response simulations of selected structures. Different LFRSs are considered, including steel moment resisting frames (SMRFs), reinforced concrete moment resisting frames (RCMRFs), reinforced concrete shear walls (RCSWs), concentrically braced frames (CBFs), eccentrically braced frames (EBFs), masonry structures and pre-cast structures. The correlations between the derived period expressions with those recommended by the design provisions show that the code approach is conservative enough for SMRFs, CBFs, masonry buildings and pre-cast structures. For RCMRFs, EBFs and RCSWs, the design code is slightly unconservative for low-rise buildings. The outcomes of the study help to arrive at more efficient and cost-effective seismic design of buildings with different characteristics.

Code-Oriented Methodology for the Seismic Design of Regular Steel Moment-Resisting Braced Frames

2014 ◽  
Vol 30 (4) ◽  
pp. 1683-1709 ◽  
Author(s):  
Edgar Tapia-Hernández ◽  
Arturo Tena-Colunga
Keyword(s):  
Seismic Design ◽  
Time History ◽  
Federal District ◽  
Design Parameters ◽  
Braced Frames ◽  
Steel Buildings ◽  
Moment Frames ◽  
Concentrically Braced Frames ◽  
Design Spectrum ◽  
Moment Resisting

In order to help improve the seismic design of regular steel buildings structured with ductile moment-resisting concentrically braced frames (MRCBFs) using the general design methodology of Mexico's Federal District Code (MFDC-04), suitable design parameters were first assessed using the results of pushover analyses of 13 regular MRCBFs. In order to insure collapse mechanisms consistent with the assumptions implicit in a code-based design (strong-column/weak-beam/weaker-brace), it is proposed to relate the minimum strength ratio for the resisting columns of the moment frames and the bracing system. Improved equations are proposed for a more realistic assessment of ductility and overstrength factors. In a second stage, the effectiveness of the improved methodology was assessed with the design of six regular steel buildings with MRCBFs. Buildings were evaluated by performing both pushover and nonlinear time-history analyses under ten selected artificial ground motions related to the corresponding design spectrum.

Full-Scale Cyclic Testing of Self-Centering Modular Panels for Seismic Resilient Structures

2018 ◽  
Vol 763 ◽  
pp. 339-346 ◽  
Author(s):  
Wei Wang ◽  
Xin Long Du ◽  
Yun Feng Zhang ◽  
Gong Ling Chu ◽  
Yi Yi Chen
Keyword(s):  
Boundary Elements ◽  
Original System ◽  
Seismic Load ◽  
Lateral Stiffness ◽  
Test Results ◽  
Cyclic Testing ◽  
Moment Resisting Frame ◽  
Vertical Boundary ◽  
Concentrically Braced ◽  
Moment Resisting

This paper presents a new seismic load-resisting system termed self-centering modular panel (SCMP) which provides lateral stiffness and self-centering stiffness for tension-only concentrically braced beam-through frames (TOCBBTFs). The SCMP is a posttensioned (PT) steel moment resisting frame, which consists of horizontal boundary elements (HBEs), vertical boundary elements (VBEs) and PT strands. The self-centering stiffness is provided by the PT HBE-to-VBE connections. Specimens of original TOCBBTF and TOCBBTF with SCMP were tested to investigate the function of the SCMP. The test results show that compared to the original TOCBBTF, the TOCBBTF with SCMP was capable of recentering after 4% drift of loading. Moreover, after severe cyclic loading and replacement of the damaged bracings, the repaired TOCBBTF with SCMP exhibited almost identical stiffness, strength and recentering ability to that of the original system.

Seismic design of steel buildings: lessons from the 1995 Hyogo-ken Nanbu earthquake

1996 ◽  
Vol 23 (3) ◽  
pp. 727-756 ◽  
Author(s):  
Robert Tremblay ◽  
Andre Filiatrault ◽  
Michel Bruneau ◽  
Masayoshi Nakashima ◽  
Helmut G. L. Prion ◽  
...  
Keyword(s):  
Seismic Design ◽  
Steel Structures ◽  
Structural Systems ◽  
Braced Frames ◽  
Steel Buildings ◽  
Concentrically Braced Frames ◽  
Framed Structures ◽  
Concentrically Braced ◽  
Moment Resisting ◽  
Column Bases

Past and current seismic design provisions for steel structures in Japan are presented and compared with Canadian requirements. The performance of steel framed structures during the January 17, 1995, Hyogo-ken Nanbu earthquake is described. Numerous failures and examples of inadequate behaviour could be observed in buildings of various ages, sizes, and heights, and braced with different structural systems. In moment resisting frames, the damage included failures of beams, columns, beam-to-column connections, and column bases. Fracture of bracing members or their connections was found in concentrically braced frames. The adequacy of the current Canadian seismic design provisions is examined in view of the observations made. Key words: earthquake, seismic design, steel structures.

scholarly journals IMPACT OF INTRODUCING SEMI-RIGID MOMENT FRAMES ON SEISMIC RESPONSE OF BRACED FRAMES

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mahmoud Faytarouni ◽  
Onur Seker ◽  
Bulent Akbas ◽  
Jay Shen
Keyword(s):  
Braced Frames ◽  
Seismic Evaluation ◽  
Moment Frames ◽  
Moment Frame ◽  
Braced Frame ◽  
Shear Connections ◽  
Seismic Force ◽  
Steel Building ◽  
Story Drift ◽  
Moment Resisting

Maximum seismic inelastic drift demand in a steel building with braced frames as primary seismic-force-resisting (SFR) system tends to concentrate in few stories without considering inherent participation of designed gravity-force-resisting (GFR) system in actual structural stiffness and strength. The influence of GFR system on stiffness and strength can be taken into account by considering the composite action in beam-to-column shear connections that exist in modern steel building construction to form actual semi-rigid moment-resisting frames. Therefore, modeling semi-rigid moment frames as an equivalent to the GFR system in braced frame buildings could be utilized as a representative to the strength provided by gravity frames. This paper presents a seismic evaluation of a six-story chevron braced frame, with and without semi-rigid moment frame. Four different cases are investigated under a set of ground motions and results are discussed in terms of story drift distribution along the height. The results pointed out that the current findings lay a foundation to conduct further investigation on the seismic performance of braced frames as designed SFR system together with GFR system.

scholarly journals STRUCTURAL ANALYSIS OF APARTMENT BUILDING WITH SPECIAL RESISTING FRAME SYSTEM

2020 ◽  
Vol 2 (1) ◽  
pp. 9-15
Author(s):  
Sita Ramandhani Arumsari Susanto ◽  
Koespiadi Koespiadi
Keyword(s):  
Soft Soil ◽  
Earthquake Risk ◽  
Seismic Load ◽  
Building Structure ◽  
Apartment Building ◽  
Moment Resisting Frame ◽  
Column Structure ◽  
Moment Resisting ◽  
Frame System ◽  
Special Moment Resisting Frame

Indonesia has a high earthquake risk, therefore several buildings in Indonesia are designed with seismic retention systems where the column structure is designed to be stronger than the beam. The calculation of apartment building structure in this final design is based on SNI 1726:2012 and SNI 2847:2013. The method used in this calculation is the Special Moment Resisting Frame System (SMRFS) because the building area is included in the category of E seismic design which is a type of soft soil. The Special Moment Resisting Frame System is designed so that the building has more strength to withstand earthquakes, especially the column structure. This building is classified as a high-level building, therefore the analysis of seismic load is carried out by Spectrum Response Dynamic, using the SRSS (Square Root of the Sum Squares) method because the building structure has far-flung natural vibration times. In high-rise buildings, it is necessary to control the displacement between floors to reduce the large sway on each floor. The displacement between floors resulting from elastic analysis is less than the maximum allowable intersection between floors. so that the building structure is still safe against swaying.  

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