Assessment of seismic design parameters of moment resisting RC braced frames with metallic fuses

2015 ◽  
Vol 95 ◽  
pp. 138-153 ◽  
Author(s):  
A. Tena-Colunga ◽  
H.J. Nangullasmú-Hernández
Keyword(s):  
Seismic Design ◽  
Design Parameters ◽  
Braced Frames ◽  
Moment Resisting

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.

Research on Hysteretic Behavior of Angle Beam-Column Connections

2010 ◽  
Vol 163-167 ◽  
pp. 686-691
Author(s):  
Feng Xia Li
Keyword(s):  
Energy Dissipation ◽  
Seismic Design ◽  
Hysteretic Behavior ◽  
Design Parameters ◽  
Dissipation Process ◽  
Flange Thickness ◽  
Rigid Deformation ◽  
Moment Resisting ◽  
Angle Steel ◽  
Earthquake Effects

In practice most connections actually show semi-rigid deformation behavior that can contribute substantially to overall displacements of the structure and to the distribution of member forces. So it is very necessary that studying the behavior of these semi-rigid connections under cyclic reversal loading. Two full-scale specimens of top-mounted-angle using H-section member had been conducted. The specimens were subjected to cyclic reversal loading simulating earthquake effects on a steel moment-resisting force. The objective of the work is to determine the behavior of these connections under cyclic reversal loading well into the inelastic range and to ascertain the effect of design parameters such as column flange stiffener, pre-tension of bolts and the top-mounted-angle steel flange thickness on the overall behavior. Observations were made concerning the response of the connections and its elements in terms of strength, stiffness and energy dissipation. Information on the design of these connections is presented. It is concluded that top-mounted-angle connections can possess the relative high stiffness, strength and excellent ductility as moment-resisting components in the seismic design of frames. Most of the input energy was dissipated in top-mounted-angle while the column participated a little in the energy dissipation process in the test. It is analyzed that the preload of bolt, contact pressure of the components and the other components’ mechanical properties by nonlinear analysis. These consequences are good reference for the engineering design.

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.

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.

Derivation of Seismic Design Parameters for ECC and Multi-Material Special Moment-Resisting Frames

2016 ◽  
Vol 20 (7) ◽  
pp. 1054-1076 ◽  
Author(s):  
Bora Gencturk ◽  
Ibrahim Kaymaz ◽  
Farshid Hosseini
Keyword(s):  
Seismic Design ◽  
Design Parameters ◽  
Moment Resisting Frames ◽  
Moment Resisting

Experimental Research on Hysteretic Behavior of Top-Seat Angles Beam-Column Connections

2012 ◽  
Vol 166-169 ◽  
pp. 110-113
Author(s):  
Xin Wu Wang ◽  
Dong Han
Keyword(s):  
Energy Dissipation ◽  
Seismic Design ◽  
Carrying Capacity ◽  
Hysteretic Behavior ◽  
Design Parameters ◽  
Rotational Stiffness ◽  
Dissipation Process ◽  
Flange Thickness ◽  
Moment Resisting ◽  
Earthquake Effects

Abstract. Two full-scale specimens of angles steel using H-section member had been conducted. The specimens were subjected to cyclic reversal loading simulating earthquake effects on a steel moment-resisting force. The objective of the work is to determine the behavior of these connections under cyclic reversal loading well into the inelastic range and to ascertain the effect of design parameters such as column flange stiffener, pre-tension of bolts and the angles flange thickness on the overall behavior. Observations were made concerning the response of the connections and its elements in terms of strength, stiffness and energy dissipation. Information on the design of these connections is presented. The hysteretic behavior of angles beam-column connections under cyclic loading is presented in this paper. Rotational stiffness, the carrying capacity and ductility of top-seat angles connections are analyzed. It is concluded that angles connections can possess the relative high stiffness, strength and excellent ductility as moment-resisting components in the seismic design of frames. Most of the input energy was dissipated in the flange of angles while the column participated a little in the energy dissipation process in the test.

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.

scholarly journals Seismic Behavior of Concentrically Braced Steel Frames with Out-of-Plane Offset Irregularity

2017 ◽  
Vol 11 (1) ◽  
pp. 485-495 ◽  
Author(s):  
Amin Mohebkhah ◽  
Marzieh Akefi
Keyword(s):  
Seismic Design ◽  
Seismic Behavior ◽  
Steel Frames ◽  
Design Parameters ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Overstrength Factor ◽  
Concentrically Braced ◽  
Out Of Plane ◽  
Story Drift

Braced steel frames are sometimes designed with out-of-plane shifted bracing members on the first story due to architectural or functional considerations. Such frames are classified and designated as frames having the Type-4 horizontal structural irregularity entitled “frames with out-of-plane offset irregularity” as per theMinimum Design Loads for Building and Other Structures(ASCE 7-10). The purpose of this study is to investigate the nonlinear seismic behavior of ordinary steel concentrically braced frames with out-of-plane offset irregularity and evaluate their seismic design parameters. To this end, two 3-story and 6-story three-dimensional ordinary concentrically braced frames (OCBFs) with and without out-of-plane offset of one of the vertical elements on the first story were considered (i.e. irregular and regular configurations). The seismic design parameters considered in this study includes: frame overall overstrength factor, column overstrength factor and the inelastic dynamic inter-story drift demands. Nonlinear time-history dynamic analysis of the frames showed that overall overstrength factor of the low- and mid-rise irregular frames studied in this research is lower than that of the regular ones. Moreover, it was found that theSeismic Provisionsprescribed overstrength factor (i.e. Ωo=2.0) to amplify columns axial seismic forces in OCBFs is not conservative for the studied regular frames’ columns as well as the columns in the vicinity of the shifted bracing members on the first story of the irregular frames. Also, it was shown that the studied low- and mid-rise regular and irregular concentrically braced frames experience greater inter-story drift demands than predicted by the amplified elastic analysis proposed in the codes.

Accounting for overstrength in seismic design of steel structures

1998 ◽  
Vol 25 (1) ◽  
pp. 1-15 ◽  
Author(s):  
M A Rahgozar ◽  
J L Humar
Keyword(s):  
Seismic Design ◽  
Slenderness Ratio ◽  
Steel Structures ◽  
Building Structures ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Design Loads ◽  
Reserve Strength

Observations during many earthquakes have shown that building structures are able to sustain without damage earthquake forces considerably larger than those they were designed for. This is explained by the presence in such structures of significant reserve strength not accounted for in design. Relying on such overstrength, many seismic codes permit a reduction in design loads. The possible sources of reserve strength are outlined in this paper, and it is reasoned that a more rational basis for design would be to account for such sources in assessing the capacity rather than in reducing the design loads. As an exception, one possible source of reserve strength, the redistribution of internal forces, may be used in scaling down the design forces. This is because such scaling allows the determination of design forces through an elastic analysis rather than through a limit analysis. To assess the extent of reserve strength attributable to redistribution, steel building structures having moment-resisting frames or concentrically braced frames and from 2 to 30 storeys in height are analyzed for their response to lateral loading. A static nonlinear push-over analysis is used in which the gravity loads are held constant while the earthquake forces are gradually increased until a mechanism forms or the specified limit on interstorey drift is exceeded. It is noted that in moment-resisting frames the reserve strength reduces with an increase in the number of storeys as well as in the level of design earthquake forces. The P→Δ effect causes a further reduction. In structures having braced frames the main parameter controlling the reserve strength is the slenderness ratio of the bracing members. In these structures, reserve strength is almost independent of both the height of the structure and the effect of building sway. Key words: seismic design, overstrength factor, reserve strength owing to redistribution, steel moment-resisting frames, steel-braced frames, push-over analysis.

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