scholarly journals Optimum Performance-Based Design Of Unsymmetrical 2D Steel Moment Frame

2021 ◽  
Author(s):  
Arezoo Asaad Samani ◽  
Seyed Rohollah Hoseini Vaez ◽  
Mohammad Ali Fathali
Keyword(s):  
Lateral Loading ◽  
Performance Based Design ◽  
Nonlinear Static Analysis ◽  
Second Step ◽  
Analysis Method ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting ◽  
Nonlinear Static

Abstract The most commonly used analysis method in performance-based design (PBD) is the nonlinear static analysis (NSA). In unsymmetrical 2D frames, unlike its symmetrical state, NSA should be performed in two lateral loading directions, which complicates the process of achieving a feasible optimal design in addition to increasing the volume of calculations. In this study, a two-step approach is proposed for the design of unsymmetrical 2D steel moment-resisting frames (SMRF). In this approach, in two independent steps, the structure is analyzed with lateral loading pattern based on the first mode shape in positive and negative direction, respectively. The implementation of the second step is conditional on the satisfactory completion of the first step. The objective function takes into account the differences between successful and unsuccessful steps. The constraints considered are based on the acceptance criteria for SMRFs according to FEMA-356 at each performance level. The effectiveness of the proposed approach has been investigated by employing four meta-heuristic optimization algorithms to determine the optimum design for case studies of SMRF structures having three and nine stories.

scholarly journals Accuracy of Advanced Methods for Nonlinear Static Analysis of Steel Moment-Resisting Frames

2014 ◽  
Vol 8 (1) ◽  
pp. 310-323 ◽  
Author(s):  
Massimiliano Ferraioli ◽  
Alberto M. Avossa ◽  
Angelo Lavino ◽  
Alberto Mandara
Keyword(s):  
Pushover Analysis ◽  
Nonlinear Static Analysis ◽  
Seismic Demands ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Capacity Spectrum ◽  
History Analysis ◽  
Moment Resisting ◽  
Response History Analysis ◽  
Nonlinear Static

The reliability of advanced nonlinear static procedures to estimate deformation demands of steel momentresisting frames under seismic loads is investigated. The advantages of refined adaptive and multimodal pushover procedures over conventional methods based on invariant lateral load patterns are evaluated. In particular, their computational attractiveness and capability of providing satisfactory predictions of seismic demands in comparison with those obtained by conventional force-based methods are examined. The results obtained by the static advanced methods, used in the form of different variants of the original Capacity Spectrum Method and Modal Pushover Analysis, are compared with the results of nonlinear response history analysis. Both effectiveness and accuracy of these approximated methods are verified through an extensive comparative study involving both regular and irregular steel moment resisting frames subjected to different acceleration records.

scholarly journals Assessment of seismic responses toward multi-story buildings of steel special moment resisting frame by considering the setback irregularities

2021 ◽  
Vol 331 ◽  
pp. 05007
Author(s):  
Ridho Aidil Fitrah ◽  
Masrilayanti Masrilayanti ◽  
Gita Zakiah Putri ◽  
Zev Al Jauhari
Keyword(s):  
Response Spectrum ◽  
Nonlinear Static Analysis ◽  
Steel Buildings ◽  
Seismic Responses ◽  
Base Shear ◽  
Moment Frame ◽  
Moment Resisting ◽  
Drift Limit ◽  
Special Moment Resisting Frame ◽  
Special Moment Frame

Setback irregularities are considered where discontinuity between adjacent stories is excessive. This irregularity caused the probability of high damage at structures subjected to strong earthquake motion. For this purpose, this study was conducted by modeling the steel special moment frame (SMF) structures using a finite element calculation program with nonlinear static analysis compared to Padang city’s response spectrum. The buildings are also modeled with two types of setbacks: single and multiple setbacks. The results of this paper are discussed including the explanation of many parameters that relate to elastic and inelastic seismic responses of steel special moment frame (SMF). Based on the results, the setback irregularities, both single and multiple setbacks, the inelastic seismic responses are adequately sufficient to SNI 1726 2019 regarding drift limit. The other seismic responses are also discussed in terms of fundamental periods, inter-story drifts, story stiffness, and base shear. Referred to Indonesian Seismic Provision, SNI 1726 2019, it is found that single setback building has more adequate than multiple setbacks in terms of seismic responses. Then, the seismic assessments between these setbacks are explained to address the recommendations about future prevention toward damages and failures in steel buildings.

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.

The Sliding Hinge Joint: Final Steps towards an Optimum Low Damage Seismic-Resistant Steel System

2018 ◽  
Vol 763 ◽  
pp. 751-760 ◽  
Author(s):  
Shahab Ramhormozian ◽  
George Charles Clifton ◽  
Gregory A. MacRae ◽  
Hsen Han Khoo
Keyword(s):  
Large Scale ◽  
Limit State ◽  
Model Development ◽  
Research Work ◽  
Research Programme ◽  
Service Condition ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Hinge Joint ◽  
Moment Resisting

The Sliding Hinge Joint with Asymmetric Friction Connectors (SHJ), to give its full name, is a semi-rigid moment resisting joint used between the beams and columns of a moment-resisting steel frame and also at the column base between the column and the ground. It’s performance is intended to be as follows: 1) On completion of construction, rigid under serviceability limit state conditions, 2) During a severe earthquake, allowing controlled rotation between the column and the beam or foundation on designated friction sliding planes within the connection, then 3) Returning to its rigid in-service condition at the end of the severe shaking with the building returning to its pre-earthquake position (self-centering). During its development and proof of concept through large scale testing, the initial results showed that the SHJ as originally designed and detailed performs 1) and 2) very well, but the bolts in the friction sliding planes loose much of their original installed bolt tension during significant sliding, lowering the level at which rotation within the joint will occur post severe earthquake. A concerted research programme of component testing, analytical model development and numerical modelling in recent years has developed solutions to the bolt tension loss issue as well as enhanced the joint’s performance to deliver dependable self-centering capability for the building. This work marks the final steps towards developing an optimum low damage seismic-resisting steel moment frame system. This paper presents key findings from the research work and general recommendations for the optimum performing sliding hinge joint.

scholarly journals Numerical Analysis of Masonry Assemblages through Simplified Micro-Modeling

2020 ◽  
Vol 20 (6) ◽  
pp. 7-13
Author(s):  
Dong-Jin Yoon ◽  
Kwang-Mo Lim ◽  
Joo-Ha Lee
Keyword(s):  
Performance Evaluation ◽  
Masonry Wall ◽  
Nonlinear Static Analysis ◽  
Analysis Method ◽  
Equivalent Strut ◽  
Reinforced Masonry ◽  
Micro Modeling ◽  
Nonlinear Static ◽  
Evaluation Techniques ◽  
Significant Attention

Recently, research focused on preventing the aging of masonry structures, and minimization of damage caused by earthquakes to these structures has gained significant attention. To improve the performance of these structures, an appropriate method is required for their performance evaluation. Generally, the equivalent strut model is employed for the performance evaluation of a masonry wall. However, this method is known to have limitations in implementing reinforced masonry and in reflecting the actual reinforcement effect. Appropriate evaluation techniques should be developed to implement the performance improvement methods developed in the future. Therefore, in this study, analysis methods were developed considering the nonlinear static analysis method for masonry elements. In addition, using these methods, the analysis considering the various reinforced thicknesses and shapes was performed, and the appropriate reinforcement methods were presented for these structures.

scholarly journals Application of Nonlinear Static Procedures for the Seismic Assessment of Regular RC Moment Frame Buildings

2014 ◽  
Vol 30 (2) ◽  
pp. 767-794 ◽  
Author(s):  
Michalis Fragiadakis ◽  
Dimitrios Vamvatsikos ◽  
Mark Aschheim
Keyword(s):  
Pushover Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Single Mode ◽  
Moment Frame ◽  
Seismic Demands ◽  
Frame Buildings ◽  
Moment Resisting ◽  
Nonlinear Static ◽  
Global And Local ◽  
Modal Pushover

The applicability of nonlinear static procedures for estimating the seismic demands of typical regular RC moment-resisting frames is evaluated. This work, conducted within the framework of the ATC-76-6 project, shows the degree to which nonlinear static methods can characterize global and local response demands vis-à–vis those determined by nonlinear dynamic analysis for three RC moment-frame buildings. The response quantities (engineering demand parameters) considered are peak story displacements, story drifts, story shears, and floor overturning moments. The single-mode pushover methods evaluated include the N2 and the ASCE-41 coefficient methods. Multi-modal pushover methods, such as modal pushover analysis and the consecutive modal pushover method, were also evaluated. The results indicate that the relatively good performance of the single-mode methods observed for low-rise buildings rapidly deteriorates as the number of stories increases. The multi-modal techniques generally extend the range of applicability of pushover methods, but at the cost of additional computation and without ensuring the reliability of the results.

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