Analytical Methodology to Predict the Beam Overstrength Considering the Composite Slab Effects

2018 ◽  
Vol 763 ◽  
pp. 826-834
Author(s):  
Tushar Chaudhari ◽  
Gregory A. MacRae ◽  
Des Bull ◽  
George Charles Clifton ◽  
Stephen Hicks
Keyword(s):  
Steel Frames ◽  
Lateral Force ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Design Strength ◽  
Analytical Methodology ◽  
Panel Zone ◽  
Proposed Model ◽  
The World ◽  
Moment Resisting

The design strength of moment resisting steel frames in seismic regions around the world is generally calculated without considering strength enhancement caused by the slab. For column and panel zone design in New Zealand, the beam overstrength including the slab effect is considered. If the slab could be detailed to provide reliable lateral force resistance, then considering it directly in design would result in smaller beam sizes and more economical steel frames. In this paper, a simple analytical model (considering all key modes of failures) to predict the variation in strength due to the presence of the slab is proposed and validated with the experimental data. The proposed model to develop dependable slab contributions may change the design of steel moment frames around the world.

Design Guidelines for Steel Moment Frames for New Buildings

2003 ◽  
Vol 19 (2) ◽  
pp. 269-290
Author(s):  
C. Mark Saunders
Keyword(s):  
Lateral Force ◽  
Design Guidelines ◽  
Northridge Earthquake ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Simple Set ◽  
Frame Buildings ◽  
New Buildings

The damage to steel moment frames observed in the Northridge earthquake of 1994 led to requirements in codes for use of tested connections, when these systems were to be employed in new buildings. One of the primary goals of the FEMA/SAC project was to develop guidelines for the design of steel moment frames that would return the design process to a relatively simple set of procedures similar to those used in the design of other lateral force-resisting systems. Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings, FEMA-350, presents design guidelines for use of steel moment frames in new buildings, developed from the FEMA/SAC research. This paper provides a general summary of the criteria, and a description of the prequalified connections and recommendations for their use.

Effect of Column-Base Flexibility on the Seismic Response and Safety of Steel Moment-Resisting Frames

2013 ◽  
Vol 29 (4) ◽  
pp. 1537-1559 ◽  
Author(s):  
Farzin Zareian ◽  
Amit Kanvinde
Keyword(s):  
Nonlinear Response ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Steel Moment Resisting Frames ◽  
Four Frames ◽  
Plastic Mechanism ◽  
Fixed Base ◽  
Moment Resisting ◽  
Ductility Capacity ◽  
Column Base

The effect of column-base flexibility on the response of steel moment frames is assessed through parametric simulation. The response of four frames (2-, 4-, 8-, and 12-story), designed as per current codes, is investigated through static push-over simulations and sophisticated nonlinear response-history simulations, including collapse simulation. For each frame, a range of base fixities is interrogated, including realistic values that are calculated from the designed connections. The results indicate that a reduction in base fixity alters the force distribution and the plastic mechanism, significantly reducing ductility capacity and strength, as well as collapse resilience, while increasing member forces. For the 4-, 8-, and 12-story frames, this trend suggests that the expected response of such frames is worse than is implied by simulations and design approaches that assume a fixed-base condition. However, the trend is beneficial for the 2-story frame, which is analyzed and designed assuming a pinned base.

Extant Panel Zone Design Procedures for Steel Frames Are Questioned

1999 ◽  
Vol 15 (2) ◽  
pp. 361-369 ◽  
Author(s):  
Robert E. Englekirk
Keyword(s):  
Steel Frames ◽  
Code Design ◽  
Moment Frames ◽  
Design Procedures ◽  
Panel Zone ◽  
Special Moment Frames ◽  
Current Design ◽  
Current Code ◽  
Observed Behavior

Current design procedures for steel special moment frames (SMF) promote panel zone yielding. Reliance on this yielding is likely to result in poor frame performance in spite of the fact that it has been demonstrated that panel zones can yield. Eight previously tested subassemblies are analyzed for compliance with current code design procedures. The observed behavior of these subassemblies is discussed and contrasted to behavior objectives of steel SMF's. Revised design procedures are proposed.

Hysteresis Behavior of Square Tube Columns to H-Beam Connections with Vertical Stiffeners

2005 ◽  
Vol 8 (6) ◽  
pp. 561-572 ◽  
Author(s):  
Jinan Chung ◽  
Seongyon Seo ◽  
Chiaki Matsui ◽  
Sungmo Choi
Keyword(s):  
Test Methods ◽  
Test Results ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Steel Moment Resisting Frames ◽  
Simply Supported ◽  
Moment Resisting Frames ◽  
Connection Method ◽  
Moment Resisting ◽  
H Beam

This paper deals with confirming the usability of a new connection method for steel moment-resisting frames. The connections are strengthened with vertical stiffeners to connect square tube columns and H-shaped beams. Two test methods were selected with experimental parameters given as details. The first test is performed under symmetrical loading. Beams are simply supported on both ends and test load is applied to the top of the column. The second test is performed under anti-symmetric loading. The shape of test specimens is cruciform, with a beam and a column. The top end and base of the column are simply supported, and load is applied to both ends of the beam. Test results are summarized to investigate structural performances of the connection. Nonlinear FE analysis using ANSYS for moment-resisting frames was performed to confirm the test results. It was found that all specimens had sufficient capacities exceeding the full plastic strength of beam. Therefore, the connections strengthened with vertical stiffeners were successfully verified to have possibility as a new connection method for steel moment-frames.

scholarly journals Optimization of steel moment frames with panel-zone design using an adaptive differential evolution

2020 ◽  
Vol 14 (2) ◽  
pp. 65-75
Author(s):  
Viet-Hung Truong ◽  
Ha Manh Hung ◽  
Pham Hoang Anh ◽  
Tran Duc Hoc
Keyword(s):  
Differential Evolution ◽  
Differential Evolution Algorithm ◽  
Adaptive Mutation ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Panel Zone ◽  
Local Searches ◽  
Direct Design ◽  
Adaptive Differential Evolution ◽  
Mutation Strategy

Optimization of steel moment frames has been widely studied in the literature without considering shear deformation of panel-zones which is well-known to decrease the load-carrying capacity and increase the drift of structures. In this paper, a robust method for optimizing steel moment frames is developed in which the panel-zone design is considered by using doubler plates. The objective function is the total cost of beams, columns, and panel-zone reinforcement. The strength and serviceability constraints are evaluated by using a direct design method to capture the nonlinear inelastic behaviors of the structure. An adaptive differential evolution algorithm is developed for this optimization problem. The new algorithm is featured by a self-adaptive mutation strategy based on the p-best method to enhance the balance between global and local searches. A five-bay five-story steel moment frame subjected to several load combinations is studied to demonstrate the efficiency of the proposed method. The numerical results also show that panel-zone design should be included in the optimization process to yield more reasonable optimum designs. Keywords: direct design; differential evolution; optimization; panel-zone; steel frame.

Multi-Hazard Risk Mitigation through Application of Seismic Design Rules

2018 ◽  
Vol 763 ◽  
pp. 1139-1146 ◽  
Author(s):  
Dan Dubină ◽  
Florea Dinu ◽  
Ioan Marginean
Keyword(s):  
Seismic Design ◽  
Risk Mitigation ◽  
Progressive Collapse ◽  
Steel Structures ◽  
Lateral Force ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Design Concepts ◽  
Collapse Resistance ◽  
Extreme Hazards

Multi-story buildings often use steel moment frames as lateral force resisting systems, because such systems would allow architectural flexibility, while providing the strength, stiffness, and ductility required to resist the gravity, wind, and seismic loads. Steel moment frames on which capacity design concepts are applied to resist earthquake induced forces, are generally considered robust structures, with adequate resistance against collapse for other extreme hazards, for example blast or impact. Starting from this point, the present paper summarizes the results of some recent studies carried out in the Department of Steel Structures and Structural Mechanics and CEMSIG Research Center from Politehnica University Timisoara, aiming to evaluate the influence of beam-to-column joints, designed to satisfy seismic design requirements, on the progressive collapse resistance of multi-story steel frame buildings.

scholarly journals DETERMINING THE OPTIMAL GEOMETRY OF RBS CONNECTION FOR ENHANCEMENT OF SEISMIC BEHAVIOR OF STEEL MOMENT FRAMES

2016 ◽  
Vol 38 (2) ◽  
pp. 1116
Author(s):  
Hossein Khosravi ◽  
Vahidreza Kalatjari ◽  
Hadi Einabadi
Keyword(s):  
Seismic Behavior ◽  
Plastic Hinge ◽  
Seismic Loads ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Finite Element Software ◽  
Cutting Geometry ◽  
Panel Zone ◽  
Local Reduction ◽  
Beam Section

In a RBS connection, the stress concentration is being prevented on the location of joint via local reduction of beam section near the column and the place of plastic hinge is being transferred from connection to a section of a beam near to the column. A special ilk of RBS connection which is named dogbone connection and its beam wings are cut from a circle in an arcuate form, has displayed a desirable performance against to the seismic loads. This paper aims at obtaining the best cutting geometry of the beam wing in order to improve the performance of the connection against to the seismic loads. For this purpose in this research, we have opted a several panel zone with different dimension on the beam wing under the influence of the seismic loads in Finite Element software called Abaqus along with a cyclic loading, modeled displacement control index and the best sample of cutting dimension among from the samples that are modeled.

Effects of Fling Step and Forward Directivity on Seismic Response of Buildings

2006 ◽  
Vol 22 (2) ◽  
pp. 367-390 ◽  
Author(s):  
Erol Kalkan ◽  
Sashi K. Kunnath
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
High Amplitude ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Damage Potential ◽  
Near Fault ◽  
Forward Directivity ◽  
Fling Step ◽  
Far Fault

This paper investigates the consequences of well-known characteristics of near-fault ground motions on the seismic response of steel moment frames. Additionally, idealized pulses are utilized in a separate study to gain further insight into the effects of high-amplitude pulses on structural demands. Simple input pulses were also synthesized to simulate artificial fling-step effects in ground motions originally having forward directivity. Findings from the study reveal that median maximum demands and the dispersion in the peak values were higher for near-fault records than far-fault motions. The arrival of the velocity pulse in a near-fault record causes the structure to dissipate considerable input energy in relatively few plastic cycles, whereas cumulative effects from increased cyclic demands are more pronounced in far-fault records. For pulse-type input, the maximum demand is a function of the ratio of the pulse period to the fundamental period of the structure. Records with fling effects were found to excite systems primarily in their fundamental mode while waveforms with forward directivity in the absence of fling caused higher modes to be activated. It is concluded that the acceleration and velocity spectra, when examined collectively, can be utilized to reasonably assess the damage potential of near-fault records.

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