Probability assessment of structural response modification factor of RC frames by the demand-capacity-factor method

Structures ◽  
2021 ◽  
Vol 30 ◽  
pp. 628-637
Author(s):  
Shuangshuang Cui ◽  
Yan Chen ◽  
Dagang Lu
Keyword(s):  
Structural Response ◽  
Capacity Factor ◽  
Probability Assessment ◽  
Response Modification Factor ◽  
Factor Method ◽  
Rc Frames ◽  
Modification Factor

scholarly journals Response Modification Factor of RC Frames Strengthened with RC Haunches

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Junaid Akbar ◽  
Naveed Ahmad ◽  
Muhammad Rizwan ◽  
Sairash Javed ◽  
Bashir Alam
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Lateral Force ◽  
Roof Displacement ◽  
Response Modification Factor ◽  
Capacity Curves ◽  
Displacement Capacity ◽  
Rc Frames ◽  
Modification Factor ◽  
Force Displacement

This paper presents experimental and numerical studies carried out on two-story reinforced concrete (RC) frames having weaker beam-column joints, which were retrofitted with reinforced concrete haunches to avoid joint panel damage under seismic actions. The design philosophy of the retrofit solution is to allow beam-column members to deform inelastically and dissipate seismic energy. Shake table tests were performed on three 1 : 3 reduced scale two-story RC frame models, including one model incorporating construction deficiencies common in developing countries, which was retrofitted with two retrofit schemes using RC haunches. The focus of the experimental study was to understand the seismic behaviour of both as-built and retrofitted models and obtain the seismic response properties, i.e., lateral force-displacement capacity curves and time histories of model response displacement. The derived capacity curves were used to quantify overstrength and ductility factors of both as-built and retrofitted frames. Finite element- (FE-) based software SeismoStruct was used to develop representative numerical models, which were calibrated with the experimental data in simulating the time history response of structure roof displacement and in predicting peak roof-displacement and peak base shear force. Moreover, the FE-based numerical models were subjected to a suite of spectrum natural accelerograms, linearly scaled to multiple intensity levels for performing incremental dynamic analysis. Lateral force-displacement capacity and response curves were developed, which were analyzed to calculate the structure ductility and overstrength factors. The structure R factor is the product of ductility and overstrength factors, which exhibited substantial increase due to the proposed retrofitting technique. A case study was presented for the seismic performance assessment of RC frames with/without RC haunches in various seismic zones using the static force procedure given in seismic code and using response modification factor quantified in the present research.

scholarly journals Seismic response modification factor for RC-frames with non-uniform dimensions

2021 ◽  
Vol 8 (1) ◽  
pp. 1923363
Author(s):  
Manar M. Hussein ◽  
Manar Gamal ◽  
Walid A. Attia
Keyword(s):  
Seismic Response ◽  
Response Modification Factor ◽  
Rc Frames ◽  
Modification Factor

SHAKING TABLE TESTS ON HAUNCH RETROFITTED REINFORCED CONCRETE FRAMES

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 233-240
Author(s):  
Junaid Akbar ◽  
Naveed Ahmad ◽  
Bashir Alam
Keyword(s):  
Reinforced Concrete ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Concrete Frames ◽  
Seismic Behaviour ◽  
Response Modification Factor ◽  
Rc Frames ◽  
Moment Resisting ◽  
Modification Factor ◽  
Rare Earthquake

Shaking table tests were performed on five one-third reduced scale two storey reinforced concrete (RC) moment resisting frames having construction defects (using low strength concrete without confining ties in beam-column joints, larger tie spacing, and reduced longitudinal and transverse reinforcements). The deficient frames were observed to have severe joint damageability, resulting in joint panel cover spalling and core concrete crushing. Haunch retrofitting technique was adopted to upgrade the seismic behaviour of deficient RC frames. Additional four deficient RC frames were built and retrofitted with steel haunch; both axially stiffer and deformable with energy dissipation, fixed to the beam-column connections to reduce shear demand on joint panels. The as-built and retrofitted frame seismic response modification factor (R) was calculated and compared to evaluate the viability of the haunch retrofitting technique. The haunch retrofitting technique increased the lateral stiffness and strength of the structure, resulting in the increase of structure overstrength. The retrofitting increased R factor by sixty percent to one hundred percent. The presented results indicate that the technique can significantly enhance the seismic performance of deficient RC frames, particularly against the frequent and rare earthquake events.

scholarly journals Seismic Performance Assessment of Existing RC Frames with Different Ultimate Concrete Strains

2018 ◽  
Vol 4 (6) ◽  
pp. 1273
Author(s):  
Rishath Sabrin ◽  
Mohammad Al Amin Siddique ◽  
Md. K. Sohel
Keyword(s):  
Seismic Performance ◽  
Plastic Hinge ◽  
Pushover Analysis ◽  
Performance Criteria ◽  
Seismic Performance Assessment ◽  
Seismic Region ◽  
Response Modification Factor ◽  
Rc Frames ◽  
Moment Resisting ◽  
Modification Factor

In recent years, because of the older version code, inadequate design, lacks of construction supervision, change in loading pattern, damages and casualties of earthquakes or environmental degradation, buildings at risk need to be investigated frequently for safety purpose. To increase the strength and ductility capacities of deficient reinforced concrete (RC) beams, columns and beam-column joints, retrofitting may require. In this paper, a numerical investigation using nonlinear static pushover analysis is conducted to assess the seismic behavior of existing moment resisting RC frames. In numerical modeling, different plastic hinge lengths as well as different concrete ultimate strain conditions of RC members are considered. Pushover analysis has been carried out with the commercial software ETABS v.9.6.0 to evaluate structural behavior of RC frames located in a seismic region. Hinge properties simulating moment-rotation behavior of frame members considering different plastic hinge lengths as well as concrete ultimate strains are evaluated. Pushover curves are compared with each other to determine the plastic hinge length and strain values which provide better agreement with that of the default properties. Seismic performance criteria in terms of ductility, overstrength as well as response modification factor for frames are determined from pushover curves. From the analyses in general, the load carrying capacity as well as displacement at maximum lateral load and interstory drift index at any floor level of RC frames is assessed.

scholarly journals A Multi-Objective Ground Motion Selection Approach Matching the Acceleration and Displacement Response Spectra

2018 ◽  
Vol 10 (12) ◽  
pp. 4659 ◽  
Author(s):  
Yabin Chen ◽  
Longjun Xu ◽  
Xingji Zhu ◽  
Hao Liu
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Structural Response ◽  
Response Spectra ◽  
Computationally Efficient ◽  
Ground Motion Selection ◽  
Displacement Response ◽  
Rc Frames ◽  
Selection Approach ◽  
Displacement Response Spectra

For seismic resilience-based design (RBD), a selection of recorded time histories for dynamic structural analysis is usually required. In order to make individual structures and communities regain their target functions as promptly as possible, uncertainty of the structural response estimates is in great need of reduction. The ground motion (GM) selection based on a single target response spectrum, such as acceleration or displacement response spectrum, would bias structural response estimates leading significant uncertainty, even though response spectrum variance is taken into account. In addition, resilience of an individual structure is not governed by its own performance, but depends severely on the performance of other systems in the same community. Thus, evaluation of resilience of a community using records matching target spectrum at whole periods would be reasonable because the fundamental periods of systems in the community may be varied. This paper presents a GM selection approach based on a probabilistic framework to find an optimal set of records to match multiple target spectra, including acceleration and displacement response spectra. Two major steps are included in that framework. Generation of multiple sub-spectra from target displacement response spectrum for selecting sets of GMs was proposed as the first step. Likewise, the process as genetic algorithm (GA), evolvement of individuals previously generated, is the second step, rather than using crossover and mutation techniques. A novel technique improving the match between acceleration response spectra of samples and targets is proposed as the second evolvement step. It is proved computationally efficient for the proposed algorithm by comparing with two developed GM selection algorithms. Finally, the proposed algorithm is applied to select GM records according to seismic codes for analysis of four archetype reinforced concrete (RC) frames aiming to evaluate the influence of GM selection considering two design response spectra on structural responses. The implications of design response spectra especially the displacement response spectrum and GM selection algorithm are summarized.

Evaluation of response modification factor (R) of elevated concrete tanks

2012 ◽  
Vol 39 ◽  
pp. 199-209 ◽  
Author(s):  
Mostafa Masoudi ◽  
Sassan Eshghi ◽  
Mohsen Ghafory-Ashtiany
Keyword(s):  
Response Modification Factor ◽  
Modification Factor

scholarly journals Real Cyclic Load-Bearing Test of a Ceramic-Reinforced Slab

2020 ◽  
Vol 10 (5) ◽  
pp. 1763
Author(s):  
Albert Albareda-Valls ◽  
Alicia Rivera-Rogel ◽  
Ignacio Costales-Calvo ◽  
David García-Carrera
Keyword(s):  
Cyclic Load ◽  
Structural Response ◽  
Steel Structure ◽  
Steel Beams ◽  
Load Bearing ◽  
Rc Frames ◽  
Industrial Buildings ◽  
Loading And Unloading ◽  
Low Levels ◽  
The City

Ceramic-reinforced slabs were widely used in Spain during the second half of the 20th century, especially for industrial buildings. This solution was popular due to the lack of materials at that time, as it requires almost no concrete and low ratios of reinforcement. In this study, we present and discuss the results of a real load-bearing test of a real ceramic-reinforced slab, which was loaded and reloaded cyclically for a duration of one week in order to describe any damage under a high-demand loading series. Due to the design of these slabs, the structural response is based more on shear than on bending due to the low levels of concrete and the geometry and location of re-bars. The low ratio of concrete makes these slabs ideal for short-span structures, mainly combined with steel or RC frames. The slab which was analyzed in this study covers a span of 4.88 m between two steel I-beams (IPN400), and corresponds to a building from the mid-1960s in the city of Igualada (Barcelona, Spain). A load-bearing test was carried out up to 7.50 kN/m2 by using two-story sacks full of sand. The supporting steel beams were propped up in order to avoid any interference in the results of the test; without the shoring of the steel structure, deflections would come from the combination of the ceramic slab together with the steel profiles. A process of loading and unloading was repeated for a duration of six days in order to describe the cyclic response of the slab under high levels of loading. Finally, vibration analysis of the slab was also done; the higher the load applied, the higher the fundamental frequency of the cross section, which is more comfortable in terms of serviceability.

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