Seismic evaluation of concrete moment frames in existing government buildings

2009 ◽  
Vol 36 (5) ◽  
pp. 813-825
Author(s):  
G. Akhras ◽  
W. Li
Keyword(s):  
Response Spectrum ◽  
Shear Walls ◽  
Linear Segment ◽  
Seismic Evaluation ◽  
Moment Frames ◽  
Limit States ◽  
Frame Element ◽  
Weak Beam ◽  
Detailed Evaluation ◽  
Column Joint

Many government departments have hundreds of buildings located in active seismic regions. Most of these buildings were built decades ago according to old design codes, and could be vulnerable to strong or even moderate earthquakes. To evaluate the seismic performance of concrete moment frames or moment frames with shear walls in these buildings, the static, vibration and modal response spectrum analyses are carried out according to the 2005 National building code of Canda NBCC. The analysis uses 2-D finite element models consisting of frame elements and inplane elements. The frame element has a built-in rigid linear segment at each end for modeling the portion within the beam–column joint, whereas the inplane element may have openings for modeling doors and windows in shear walls. The stiffness of both elements is adjusted to include effects of shear deformation in beams and bending deformation in wall piers. The results are further adjusted to incorporate effects of torsion and accidental torsion. Then, CSA-A23.3-04 is followed for detailed evaluation on safety in limit states, “strong column – weak beam” concept and shear strength requirements. Based on this approach, a new computer program is developed to perform this evaluation with minimum input data. Important issues in each step are discussed in detail. Examples are presented, and results are compared with available existing data.

Column Moment Demands from Orthogonal Beam Twisting

2018 ◽  
Vol 763 ◽  
pp. 259-269
Author(s):  
George Webb ◽  
Kanyakon Kosinanonth ◽  
Tushar Chaudhari ◽  
Saeid Alizadeh ◽  
Gregory A. MacRae
Keyword(s):  
Lateral Displacement ◽  
Frame Structure ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Element Analysis ◽  
Soft Storey ◽  
Simply Supported ◽  
Composite Frame ◽  
Explicit Consideration ◽  
Column Joint

Beam column joint subassemblies in steel moment frames often have simply-supported gravity beams framing into the joint in the perpendicular direction. When these subassemblies undergo lateral displacement, moments enter the column from the beams. Some of these moments are directly applied from the in-plane beam and slab stresses as they contact the column, and additional moments occur as the slab causes the perpendicular simply supported beams to twist. In most design codes around the world, no explicit consideration of these moments is performed even though they may increase the likelihood of column yielding and a soft-storey mechanism. This paper quantifies the magnitude of these perpendicular beam twisting moments in typical subassemblies using inelastic finite element analysis. It is shown that for beam-column-joint-slab subassemblies where the primary and secondary beams are fully welded to the column, the addition of slab effects significantly increases the total stiffness and strength of the composite frame structure. In addition to this, it is also shown the twisting moment demand of the secondary beams increased the frames strength by approximately 2% for an imposed drift of 5% for the subassembly investigated when no gap was provided between slab and the column. It was also shown the twisting moment demand of the secondary beams increased the frames strength by approximately 10% for a maximum imposed drift of 5% for the subassembly investigated when a gap was provided between the slab and the column.

scholarly journals Investigation of Beam Column Joint with Beam Weak in Shear under Monotonic Loading

2018 ◽  
Vol 7 (2.20) ◽  
pp. 182
Author(s):  
B Mounika ◽  
P Poluraju
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Main Parameter ◽  
Analytical Study ◽  
Experimental Studies ◽  
Element Model ◽  
The Other ◽  
Shear Reinforcement ◽  
Weak Beam ◽  
Column Joint

Earthquake affected structures, mostly failure occur at beam column joints (BCJ). BCJs are categorized according to their geometrical grouping as Interior, Exterior, and Corner joints. Exterior beam column joint (i.e., terminating the beam on one of the column faces) was the most vulnerable one with respect to the plane of loading. The present study aims at ductility behaviour of exterior BCJ with conventional reinforcement using the code IS 456-2000 and with special confining reinforcement using the Code IS 13920-2016. Four number of beam-column joint specimens are considered in which the first one is detailed as per IS 456-2000, the second one as per IS 13920-2016 and the other two with 50% and 30% reduction of shear reinforcement was provided while compared with the first specimen. It is mainly to satisfy the strong column-weak beam concept as the main parameter. The test was carried out on the loading frame with hinged conditions to the column both ends, and the load is applied at the tip of the beam. The experimental studies are proven with an analytical study carried out by finite element model by using ANSYS and disparate parameters are assessed both experimentally and analytically.  

scholarly journals Simplified Data-Driven Model for the Moment Curvature of T-Shaped RC Shear Walls

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Bin Wang ◽  
Wenzhe Cai ◽  
Qingxuan Shi
Keyword(s):  
Cross Sections ◽  
Limit State ◽  
Shear Walls ◽  
Load Ratio ◽  
Ultimate Limit State ◽  
Limit States ◽  
Displacement Ductility ◽  
And Performance ◽  
Displacement Based ◽  
Ductility Capacity

Sectional deformation quantities, such as curvature and ductility, are of prime significance in the displacement-based seismic design and performance evaluation of structural members. However, few studies on the estimates of curvatures at different limit states have been performed on asymmetric flanged walls. In this paper, a parametric study was performed for a series of T-shaped wall cross-sections based on moment-curvature analyses. By investigating the effects of the axial load ratio, reinforcement content, material properties, and geometric parameters on curvatures at the yield and ultimate limit state, we interpret the variation in curvature with different influencing factors in detail according to the changes of the neutral axis depth. Based on the regression analyses of the numerical results of 4941 T-shaped cross-sections, simple expressions to estimate the yield curvature and ultimate curvature for asymmetric flanged walls are developed, and simplified estimates of the ductility capacity including curvature ductility and displacement ductility are further deduced. By comparing with the experimental results, we verify the accuracy of the proposed formulas. Such simple expressions will be valuable for the determination of the displacement response of asymmetric flanged reinforced concrete walls.

Seismic Behavior of RC Beam to Partially Steel Tubed Concrete (PSTC) Column Joints Under High Axial Load and Cyclic Loading

2016 ◽  
Vol 16 (01) ◽  
pp. 1640015 ◽  
Author(s):  
Yun Tian Wu ◽  
Yu Shan Fu ◽  
Chong-Ming Dai
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loading ◽  
Axial Load ◽  
Deformation Energy ◽  
Rc Beam ◽  
Weak Beam ◽  
Column Joint ◽  
Energy Dissipation Capacity ◽  
Beam Mechanism ◽  
Strength And Stiffness

A new type of partially steel tubed concrete (PSTC) column is proposed that is suitable to be used in new high rise reinforced concrete (RC) buildings. Three exterior joint specimens consisting of RC beams and PSTC columns and two exterior RC joint specimens were designed and tested under high axial load and cyclic loading to investigate the joint behavior in terms of failure pattern, hysteresis response, deformation, energy dissipation capacity and degradation of strength and stiffness. Test results indicate that the PSTC column can benefit the performance of the joint in terms of strength, ductility and energy dissipation capacity and can partly compensate for the unfavorable effect induced by slab. The strong column–weak beam mechanism can also be ensured in RC beam to PSTC column joint.

ASCE-41 and FEMA-351 Evaluation of E-Defense Collapse Test

2009 ◽  
Vol 25 (4) ◽  
pp. 927-953 ◽  
Author(s):  
Bruce F. Maison ◽  
Kazuhiko Kasai ◽  
Gregory Deierlein
Keyword(s):  
Seismic Evaluation ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
Seismic Rehabilitation ◽  
Frame Building ◽  
Weak Beam ◽  
Beam Design ◽  
Safe Side ◽  
Computer Analyses

A welded steel moment-frame building is used to assess performance-based engineering guidelines. The full-scale four-story building was shaken to collapse on the E-Defense shake table in Japan. The collapse mode was a side-sway mechanism in the first story, which occurred in spite of a strong-column and weak-beam design. Computer analyses were conducted to simulate the building response during the experiment. The building was then evaluated using the Seismic Rehabilitation of Existing Buildings (ASCE-41) and Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment-Frame Buildings (FEMA-351) for the collapse prevention performance level via linear and nonlinear procedures. The guidelines had mixed results regarding the characterization of collapse, and no single approach was superior. They mostly erred on the safe side by predicting collapse at shaking intensities less than that in the experiment. Recommendations are made for guideline improvements.

Research on Deformation Index Limits of RC Shear Walls Based on Material Damage

2014 ◽  
Vol 507 ◽  
pp. 322-327
Author(s):  
Yong Le Qi ◽  
Xin Xian Zhou ◽  
Can Dong Xie
Keyword(s):  
Seismic Performance ◽  
Shear Walls ◽  
Shear Wall ◽  
Mathematical Statistic ◽  
Material Damage ◽  
Seismic Evaluation ◽  
Deformation Index ◽  
Wall Structures ◽  
Displacement Angle ◽  
Seismic Deformation

This paper divides the seismic performance of shear wall into five levels: integrity, slight damage, slight ~ moderate damage and serious damage which are defined based on material damage. And physical and mechanical description of shear walls in each performance level is given. The displacement angle is selected as the seismic performance index limit. The numerical analysis of 524 pieces of shear walls has been made to discuss the influence on seismic deformation index limits of component according to axial compression ratio, flexure shear ratio, the nominal shear stress level, the hoop characteristic value and the reinforcement ratio of longitudinal bars. With mathematical statistic method, the calculation formula for deformation index limits of components is obtained, which can be used as the basis in the performance-based seismic evaluation of shear wall structures.

scholarly journals Stiffness-Displacement Correlation from the RC Shear Wall Tests of the SAFE Program: Derivation of a Capacity Line Model

2016 ◽  
Vol 2016 ◽  
pp. 1-21 ◽  
Author(s):  
Francisco J. Molina ◽  
Pierre Pegon ◽  
Pierre Labbé
Keyword(s):  
Normal Load ◽  
Response Spectrum ◽  
Oscillation Amplitude ◽  
Shear Walls ◽  
Logarithmic Scale ◽  
Visual Interpretation ◽  
Reinforcement Density ◽  
Safety Margins ◽  
Rc Shear Wall ◽  
Seismic Tests

The response of 13 reinforced concrete shear walls submitted to successive seismic tests has been postprocessed to produce time histories of secant stiffness and displacement oscillation amplitude. For every wall an envelope curve of displacement amplitude versus stiffness is identified which is fairly modelled by a straight line in double logarithmic scale. This relatively simple model, when used as a capacity line in combination with the demand response spectrum, is able to predict in an approximate manner the maximum response to the applied earthquakes. Moreover, the graphic representation of the demand spectrum and a unique model capacity line for a group of equal walls with different assumed design frequencies on them gives a visual interpretation of the different safety margins observed in the experiments for the respective walls. The same method allows as well constructing vulnerability curves for any design frequency or spectrum. Finally, the comparison of the different identified line models for the different walls allows us to assess the qualitative effect on the behaviour of parameters such as the reinforcement density or the added normal load.

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