scholarly journals Improving resilience of moment frames using steel pipe dampers

2018 ◽  
Vol 195 ◽  
pp. 02014
Author(s):  
Junaedi Utomo ◽  
Antonius
Keyword(s):  
Numerical Study ◽  
Steel Pipe ◽  
Frame Structures ◽  
Earthquake Risk ◽  
Moment Frames ◽  
Moment Frame ◽  
Story Drift ◽  
Moment Resisting ◽  
Lateral Displacements ◽  
The Moment

Earthquake resiliency of moment resisting frames, either new or existing ones, are important for maintaining community functionality. Improving earthquake resiliency needs a strong initiative in reducing earthquake risk. Steel pipe dampers can be used to increase earthquake resiliency. Steel pipe dampers, when installed at strategic locations in the moment frame structures, dissipate most of the earthquake energy in structures through inelastic deformation so that other components of the structure are protected. Steel pipe dampers control vibration in moment frame structures and are a disposable component in structures so that the damaged dampers can be replaced easily. Steel pipe dampers are cheap and require low workmanship, therefore the recovery time after disasters is short and the cost of recovery is low. Utilizing steel pipe dampers in passive energy dissipation systems help maintain community functionality during and after disasters. Lateral displacements were quantified and used as performance indicators. Significant drift and inter story drift reduction were achieved during a numerical study. All structural components, except the steel pipe dampers, remain elastic, indicating the effectiveness of the dampers in reducing the losses due to earthquakes.

scholarly journals Simplified Time-Dependent Column Shortening Analysis in Special Reinforced Concrete Moment Frames

2017 ◽  
Vol 62 (1) ◽  
pp. 232-249 ◽  
Author(s):  
Mohammad Jalilzadeh Afshari ◽  
Ali Kheyroddin ◽  
Majid Gholhaki
Keyword(s):  
Reinforced Concrete ◽  
Frame Structures ◽  
Moment Frames ◽  
Moment Frame ◽  
High Rise ◽  
Geometrical Characteristics ◽  
Time Changes ◽  
The Moment ◽  
Long Term Behavior

Necessity for adaption of high-rise reinforced concrete structures’ design and practical steps of implementation through nonlinear staged analysis by consideration of long-term behavior of concrete have always been strongly recommended by researchers in recent years. Cumulative column shortening in conventional analyses is the most important consequence of neglecting the above issues. In this article, numerous modeling and extensive nonlinear staged analyses are carried out on structures with different geometrical characteristics and extremely simple empirical equations to estimate column shortening caused by creep, shrinkage and time changes of modulus of elasticity are provided in such a way that these relations can be independent of conventional parameters of ACI209R-92 regulations used in prediction of mentioned axial strains. Results obtained from validation of the proposed equations show high compliance of all proposed equations for up to 30 floors and also show accuracy of proposed shrinkage equation for the moment frame structures higher than the studied range.

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.

Hysteresis effect on earthquake risk assessment of moment resisting frame structures

2021 ◽  
Vol 242 ◽  
pp. 112532
Author(s):  
Zhenhua Huang ◽  
Liping Cai ◽  
Yashica Pandey ◽  
Yong Tao ◽  
William Telone
Keyword(s):  
Risk Assessment ◽  
Hysteresis Effect ◽  
Frame Structures ◽  
Earthquake Risk ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Earthquake Risk Assessment

Interpretation of significant ground-response and structure strong motions recorded during the 1994 Northridge earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S231-S246 ◽  
Author(s):  
A. F. Shakal ◽  
M. J. Huang ◽  
R. B. Darragh
Keyword(s):  
Flexible Structures ◽  
Northridge Earthquake ◽  
Moment Frame ◽  
Ground Response ◽  
Short Period ◽  
Frame Buildings ◽  
Story Drift ◽  
San Fernando ◽  
San Fernando Valley ◽  
The Moment

Abstract Some of the largest accelerations and velocities ever recorded at ground-response and structural sites occurred during the Northridge earthquake. These motions are greater than most existing attenuation models would have predicted. Although the motions are large, the correspondence between measured acceleration and damage requires further study, since some sites with high acceleration experienced only moderate damage. Also, some peak vertical accelerations were larger than the horizontal, but in general, they are smaller and fit the pattern observed in previous earthquakes. Strong-motion records processed to date show significant differences in acceleration and velocity waveforms and amplitudes across the San Fernando Valley. Analysis of processed data from several buildings in the San Fernando Valley indicates that short-period buildings such as shear-wall buildings experienced large forces and relatively low inter-story drift during the Northridge earthquake. However, long-period (1 to 5 sec) steel or concrete moment-frame buildings experienced large inter-story drift. For this earthquake, accelerations did not always amplify from base to roof for flexible structures like the moment-frame buildings, but the displacements were always larger at the roof. The drifts at many of the moment-frame buildings were larger than the drift limit for working stress design in the building code. The records from a base-isolated building indicate that high-frequency motion was reduced significantly by the isolators. The isolators deformed about 3.5 cm, which is much less than the design displacement. The records from a parking structure show important features of the seismic response of this class of structure.

scholarly journals Experimental Study on the Seismic Performance of Steel H-Shaped Beam-to-Column Connections

2020 ◽  
Vol 20 (5) ◽  
pp. 1-9
Author(s):  
Seongyeon Seo
Keyword(s):  
Seismic Performance ◽  
Steel Structures ◽  
Initial Stiffness ◽  
Moment Frame ◽  
Shaped Beam ◽  
Shear Connections ◽  
Story Drift ◽  
Frame System ◽  
The Moment ◽  
Plastic Rotation Capacity

In terms of the moment frame system of steel structures, early brittle fractures developed in the H-shaped beam-to-column connection during the Northridge and Kobe earthquakes, thereby indicating insufficient seismic performance of these components. In this study, experiments were conducted on two-side shear connections of web and rib plate reinforcements of the flanges on an H-shaped beam-to-column connection. According to the test results, the H-shaped beam-to-column connections with two-side shear connections of beam web and rib plate reinforcements of the flanges were superior to the existing connections in terms of initial stiffness, energy dissipation capacity, and plastic rotational capacity. The test values exceeded 4.2%, 0.027 rad, and 125% in terms of story drift ratio, total plastic rotation capacity, and full plastic moment of the beam, respectively. Accordingly, the proposed H-shaped beam-to-column connection showed better performance than that of the intermediate moment frame regarding seismic design.

Braced Frame Symmetrical and Asymmetrical Friction Connection Performance

2018 ◽  
Vol 763 ◽  
pp. 216-223 ◽  
Author(s):  
Robin Xie ◽  
Jose Chanchi Golondrino ◽  
Gregory A. MacRae ◽  
George Charles Clifton
Keyword(s):  
Energy Dissipation ◽  
Coefficient Of Friction ◽  
Large Displacements ◽  
Effective Coefficient ◽  
Sliding Surface ◽  
Moment Frame ◽  
Braced Frame ◽  
Static Testing ◽  
Moment Resisting ◽  
The Moment

This paper describes quasi-static testing of Asymmetrical Friction Connection (AFC) and Symmetrical Friction Connections (SFC) in steel braces. It is shown that stable energy dissipation mechanisms have been achieved in braces using Bisalloy 500 shims on the sliding surface. When incorporated into a moment frame, the braces and the moment resisting frames underwent large displacements without significant frame yielding. The effective coefficient of friction is shown to be dependent on prying.

scholarly journals A Relative Reliability Approach for Direct Displacement-Based Seismic Design of Partially Prestressed Reinforced Concrete Frame Structures

2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
Bin Jian ◽  
Chaoyi Lei ◽  
Pingping Liao
Keyword(s):  
Reinforced Concrete ◽  
Numerical Study ◽  
Frame Structures ◽  
Risk Level ◽  
Earthquake Risk ◽  
Base Shear ◽  
Reinforced Concrete Frame ◽  
Relative Reliability ◽  
Concrete Frame ◽  
Displacement Based

A relative reliability approach for Direct Displacement-Based Design (DDBD) is first proposed in this paper, which is based on the average reliability level implicit in current Chinese design codes. By introducing a relative reliability coefficientα, the determination of reliability from DDBD is transformed to the calculation of its ratio to the average reliability of current Chinese codes. This approach not only follows the reliability principle of current Chinese codes, but also avoids the complex calculation of reliability in general. The calculation of reliability at any performance level can be transformed to the nominal reliability of frequent earthquake for the expected earthquake risk level. Meanwhile, based on the assumption of elasticity, it is shown that, under frequent earthquake risk, the calculated base shear derived from DDBD theoretically equals that from force-based design (FBD). Therefore, a revised calculation of section bearing capacity for DDBD, which follows the expression in current Chinese codes, is advised, according to the numerical study of 24 examples of Partially Prestressed Reinforced Concrete (PPRC) frame structures. Finally, this proposed approach is verified to be effective and superior by a comparative analysis of 10 examples of PPRC frames.

scholarly journals Seismic retrofit of steel frame structures

2020 ◽  
Vol 15 (2) ◽  
pp. 106-117
Author(s):  
Magdy Ismail
Keyword(s):  
Seismic Hazard ◽  
Numerical Study ◽  
Steel Structures ◽  
Seismic Retrofit ◽  
Steel Frame ◽  
Frame Structures ◽  
Base Shear ◽  
Seismic Force ◽  
Moment Resisting ◽  
Steel Frame Structures

Abstract:Moment resisting frames are considered as an effective seismic force resisting system that is used for steel structures. Some of these structures that were built in high seismic hazard zones were designed according to old strength-based design codes. Currently, these structures do not meet the requirements of the new seismic codes. Therefore, the seismic retrofit of these structures is mandatory and cannot be overlooked. Steel braces and concrete-steel composite elements are common solutions for enhancing the seismic behavior of existing steel frame structures. This paper presents a numerical study that evaluates different possible techniques for the seismic retrofit of existing steel moment-resisting frame structures. The study investigates the performance of three multi-story buildings with different heights that are located in a high seismic hazard zone. Three retrofit techniques were introduced including; 1) X-Steel braces, 2) buckling restrained composite braces, and 3) composite concrete-steel plate shear walls. The seismic performance enhancement of the studied structures was evaluated in terms of the structure’s fundamental period, maximum inter-story drift and maximum base shear-to-weight ratios. Moreover, the cost of retrofitting material was estimated for each technique and they were compared to select the retrofit technique with the least constitutive material cost.

scholarly journals Evaluation of behavior and performance of the braced/ unbraced four story of steel frame with semi rigid connection

2019 ◽  
Vol 270 ◽  
pp. 01002
Author(s):  
Daniel Rumbi Teruna
Keyword(s):  
Stiffness Parameter ◽  
Braced Frame ◽  
Analysis And Design ◽  
Moment Resisting Frame ◽  
Story Drift ◽  
Moment Resisting ◽  
Inelastic Behaviour ◽  
Rigid Connection ◽  
And Performance ◽  
The Moment

Structural analysis and design with taken into account the flexibility of the beam to the column connections of steel frameworks takes on importance of the growing development and utilization of new commercial software. However, for design purposes, the beam to the column connection are usually considered to be either pinned or fully rigid, and drastically simplifies the analysis and design procedures. In this paper, a four story of unbraced and concentric braced steel moment resisting frame having different connection stiffness is analysed using linear and nonlinear static procedure. In the finite element modelling, the semi rigid connection is modelled by rotational spring having linear moment and rotation relationship. To account the inelastic behaviour of beam and column members, concentrated plastic hinges based on FEMA 356 are applied for both ends of the member. It was found that, the response quantity of the unbraced frame are influenced by the flexibility connection. However, for the braced frame the effect of the initial connection stiffness parameter on the response quantity can be neglected due to present of the braces. Furthermore, the higher the initial connection stiffness parameter, the smallest the story drift index. Moreover, the present of the braces at the moment resisting frame (braced frame) reduce the sensitivity of the connection stiffness on the behaviour and the performance frame under consideration.

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