NUMERICAL ANALYSIS OF COLLAPSING BEHAVIOR FOR MULTI-STORY STEEL MOMENT FRAMES CONSIDERING STRENGTH DEGRADATION BY LOCAL BUCKLING

Connections are considered to be one of the most prominent components of steel moment frames and have received studious attention in recent years. The core problem of welded connections is premature brittle fracture of weld in the critical beam-to-column connection region. Within the framework of this issue, various approaches have been proposed to solve the mentioned problem. Intentional weakening of the beam web or flange is in line with the purpose of leading the plastic hinge away from the column face, hence, increasing the ductility. The aim of this research is to investigate the behavior of interior connections subjected to monotonic lateral loading in case of presence of openings in beam web or flange. To do so, an ordinary fully welded rigid connection, reduced beam section, reduced web section, and drilled flange connection models are simulated numerically, utilizing finite element software, ANSYS. The results indicate that scrupulous selection of opening sizes are of great importance to fulfill the desired outcome which is avoiding the brittle failure of connections. Furthermore, the use of drilled flange, reduced beam section, or reduced web section connections satisfy the expected performance and it is proposed to use them according to practicability, architectural and economic considerations as well as site conditions. Shear deformation and local buckling is observed in reduced web section connections while in drilled flange connections, stress concentration around the opening is critical.

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Numerical simulation on seismic collapse of thin-walled steel moment frames considering post local buckling behavior

Thin-Walled Structures ◽

10.1016/j.tws.2015.04.033 ◽

2015 ◽

Vol 94 ◽

pp. 424-434 ◽

Cited By ~ 5

Author(s):

Yongtao Bai ◽

Xuchuan Lin

Keyword(s):

Numerical Simulation ◽

Local Buckling ◽

Moment Frames ◽

Steel Moment Frames ◽

Buckling Behavior ◽

Seismic Collapse ◽

Thin Walled

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

Earthquake Spectra ◽

10.1193/1.2192560 ◽

2006 ◽

Vol 22 (2) ◽

pp. 367-390 ◽

Cited By ~ 255

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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