Ductility Reduction Factors for Masonry-Infilled Reinforced Concrete Frames

2015 ◽  
Vol 31 (1) ◽  
pp. 339-365 ◽  
Author(s):  
Manish Kumar ◽  
Durgesh C. Rai ◽  
Sudhir K. Jain
Keyword(s):  
Reinforced Concrete ◽  
Traditional Approach ◽  
Statistical Tests ◽  
Experimental Studies ◽  
Reduction Factor ◽  
Model Parameters ◽  
Deformation Model ◽  
Concrete Frames ◽  
Ductility Demand ◽  
Rc Frames

Masonry-infilled reinforced concrete (RC) frames are popular structural systems; however, there is much uncertainty in their response under seismic loads. Using the data from past experimental studies, a simple force-deformation model with three control points was developed. The effect of the model parameters on the ductility reduction factor (DRF) and ductility demand (DD) was examined. Statistical tests indicated that the ratio of residual strength to peak strength was the most significant parameter. The traditional approach to determining DRF ordinates through iteration for an assumed value of ductility may result in inappropriate DRF values because of the nonmonotonic relationship between DRF and DD. Constant ductility charts were developed to appropriately account for nonmonotonicity. It was found that the allowable DRF may be much higher if relatively weaker infill compared to the strength of the frame is used, which underscores the need for modifying code provisions because they allow relatively strong infill.

An Experimental Study on Reinforced Concrete Infilled Frames with Openings

2013 ◽  
Vol 747 ◽  
pp. 429-432 ◽  
Author(s):  
Fatih Suleyman Balik ◽  
Hasan Husnu Korkmaz ◽  
Mehmet Kamanli ◽  
Fatih Bahadir ◽  
Serra Zerrin Korkmaz ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Rc Buildings ◽  
Concrete Frames ◽  
Rc Frames ◽  
Lateral Strength ◽  
Structural Failures ◽  
Strength And Stiffness ◽  
Recent Earthquakes ◽  
Infilled Rc Frames

In the last decade, seven major earthquakes caused significant casualties and extensive structural failures. Thousands of RC buildings were severely damaged or collapsed in Turkey due to various deficiencies. This has initiated experimental studies on strengthening methods and intensive researches regarding the rehabilitation of reinforced concrete structures by introducing reinforced concrete infill walls were carried out. Strengthening of reinforced concrete frames by cast-in-place reinforced concrete infills is commonly used in practice. Many structures were also repaired using this technique after the recent earthquakes. In this experimental research, six, one-bay/two-story, 1/3-scaled non-ductile, undamaged reinforced concrete (RC) frames were constructed and tested to investigate the behavior of frames strengthened by introducing infills with or without openings. The test specimens were subjected to reversed cyclic quasi-static lateral loading. The specimens were constructed with the most commonly observed deficiencies in residential RC buildings in Turkey. The first specimen was the reference bare specimen and contained no strengthening. The other specimens were infilled with RC panels with openings having different ratios and configurations. Strength, stiffness and storey drifts of the test specimens were measured and compared. Test results indicated that infilled RC frames displayed significantly higher lateral strength and stiffness than the non-ductile bare frame considerably.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Methodology of studying the mechanical properties of composite materials (reinforced concrete)

2018 ◽  
Vol 84 (12) ◽  
pp. 61-67
Author(s):  
V. A. Eryshev
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Analytical Relationship ◽  
Hardened Concrete ◽  
Deformation Model ◽  
Joint Work ◽  
Concrete Shrinkage ◽  
Axial Tension ◽  
Tension And Compression

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.

Behavior Study of High Impact Resistant Reinforced Concrete Frames Using Crack Conduction Method

2006 ◽  
Author(s):  
Navid Heidarzadeh ◽  
S. Mohammad Razavi ◽  
Nima Shamsaei
Keyword(s):  
Reinforced Concrete ◽  
Impact Loading ◽  
Failure Modes ◽  
Side Surface ◽  
High Impact ◽  
Structural Behavior ◽  
Concrete Frames ◽  
Rc Frames ◽  
Behavior Study ◽  
Falling Weight

In this study, the influence of crack conduction method on behavior of reinforced concrete (RC) frame under iterative high impact loading were experimented. To investigate the structural behavior through large deformations and progressive damage and to identify the failure modes, the falling weight and falling height were set more than the structural strength in elastic state. A comprehensive scheme which indicated influence of location of initial cracks on behavior and failure mode of structure was developed. Falling weight impact test was conducted on twenty-one laboratory scaled RC frames which were categorized in four series regard to considered scheme. Concrete volume and compressive strength, number of longitudinal and transverse rebar were constant factors in all specimens. Deformed shape and crack patterns, developed on the side surface of the RC frames, were sketched and total deflections vs. cumulative input energy of the RC girder were plotted. The results revealed the influence of crack conduction on improving the structural behavior and extending the endurance of RC frames against iterative high impact loading.

STUDIES OF DEFLECTIONS OF STATICALLY DETERMINED REINFORCED CONCRETE BEAMS BASED ON A NONLINEAR DEFORMATION MODEL

2017 ◽  
Vol 7 (4) ◽  
pp. 9-13
Author(s):  
Denis A. PANFILOV ◽  
Vladimir Yu. CHEGLINTSEV ◽  
Vyacheslav V. ROMANCHIKOV ◽  
Yury V. ZHILTSOV
Keyword(s):  
Reinforced Concrete ◽  
Numerical Experiment ◽  
Nonlinear Deformation ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Deformation Model ◽  
Theoretical Studies ◽  
Program Complex ◽  
Nonlinear Deformation Model

In this paper theoretical studies of statically determinated bending reinforced concrete beams of rectangular cross-section on deformation indexes under the eff ect of a short-time uniformly distributed load are viewed. These theoretical studies are based on the main points of the nonlinear deformation model that takes into account the nonlinear work of concrete and fi tments taking into account discrete cracking. The results of calculating the deformation of beams by the method of SP 63.13330.2012 and by authors’ method are proposed as well as the results of a numerical experiment with the identifi cation of the stress-strain state of statically determinated beams in the form of a fi nite element model in the program complex «Lira CAD-2017R3» using a linear and non-linear sett ing of characteristics of concrete and reinforcement. Based on the results of theoretical studies, the calculation results by the methodology of the current standard with a numerical experiment, as well as with the authors’ calculation methodology are compared. All calculations and loading schemes in this technique are given taking into account the possibility of further experimental studies.

scholarly journals Effect of Different Bracing Systems in Reinforced Concrete Frames under Cyclic Loading

2020 ◽  
Vol 9 (7) ◽  
pp. 704-708
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Structural Parameters ◽  
Rc Frame ◽  
Concrete Frames ◽  
Element Analysis ◽  
Framed Structures ◽  
Rc Frames ◽  
Seismic Force ◽  
Rc Framed Structures

Reinforced concrete (RC) framed structures are widely used as load transferring system in residential and commercial buildings. Even though the RC frames are designed for gravitational and seismic forces, but they are week under severe seismic events. The main disadvantage of the framed structures is inefficient bracing systems designed in it. This investigation is conducted mainly to study the effective bracing system in the RC framed structure to transfer the seismic force. This research aims to study the seismic performance of RC frames influenced by the various types of cross bracings under cyclic loading. The finite element analysis software package ABAQUS is used to investigate the braced RC frames analytically. The research scheme consists of three RC frames; the bare frame, the bare frame with single X-bracing (X frame), double X bracing (D-X frame) along the height. The structural parameters include, load-displacement hysteresis envelope, stiffness degradation and energy absorption were studied to analyze the performance of bracings. The results showed that the X frame and D-X frame noticeably increased the lateral strength, stiffness and energy dissipation properties compared to the bare RC frame. The results also indicated that the addition of X bracing along the height significantly enhanced the structural parameters of the RC frame.

scholarly journals Strength and ductility in reinforced concrete frames designed with Mexican codes

1990 ◽  
Vol 23 (3) ◽  
pp. 184-197 ◽  
Author(s):  
M. Rodriguez
Keyword(s):  
Reinforced Concrete ◽  
Structural Damage ◽  
Analytical Models ◽  
Reinforcing Steel ◽  
Concrete Frames ◽  
Approximate Methods ◽  
Reinforced Concrete Frames ◽  
Rc Frames ◽  
Mexico Earthquake ◽  
Strength And Ductility

The strength and ductility capacities of several structural sections of members in typical reinforced concrete frames designed with Mexican Codes are calculated using analytical models for confined concrete and reinforcing steel. These ductility capacities are associated with global displacement ductilities in the RC frames using approximate methods of analysis described in this paper. Results obtained in this investigation are correlated with typical pattern of structural damage in RC frames observed during the 1985 Mexico Earthquake. Some aspects of the seismic performance of fully ductile frames designed according to the 1987 Mexico City Building Code are also discussed, as well as the effect of some mechanical properties of reinforcing steel on the strength and ductility of RC frames.

scholarly journals Impact of Earthquake Types and Aftershocks on Loss Assessment of Non-Code-Conforming Buildings: Case Study with Victoria, British Columbia

2017 ◽  
Vol 33 (2) ◽  
pp. 551-579 ◽  
Author(s):  
Solomon Tesfamariam ◽  
Katsuichiro Goda
Keyword(s):  
British Columbia ◽  
Reinforced Concrete ◽  
Earthquake Engineering ◽  
Concrete Frames ◽  
Loss Assessment ◽  
Rc Frames ◽  
Annual Probability ◽  
Story Drift ◽  
Hysteretic Characteristics ◽  
The Impact

This paper presents a study on the impact of earthquake types (shallow crustal, deep inslab, and megathrust Cascadia interface earthquakes) and aftershocks on loss assessment of non-code-conforming reinforced concrete (RC) buildings. The loss assessment is formulated within the performance-based earthquake engineering framework. The dependency between the maximum and residual inter-story drift ratios are captured using copulas. Finite-element models that take into account key hysteretic characteristics of non-ductile RC frames were adopted and incremental dynamic analysis is utilized to compute collapse risk. The proposed procedure is applied to a set of 2-, 4-, 8-, and 12-story non-ductile reinforced concrete frames located in Victoria, British Columbia, Canada. From the results, the aftershock showed marked difference for the 2-story building. At annual probability of 10−2–10−3, crustal and inslab events with Mw6.5 to Mw7.5 contributed the most to the loss as these events occur more frequently. At rarer annual probability of 10−3–10−4, the Cascadia event having Mw8.5 to Mw9.0 is predominant and contributed the most to the loss.

scholarly journals NONLINEAR MULTILEVEL ANALYSIS OF REINFORCED CONCRETE FRAMES

2016 ◽  
Vol 7 (4) ◽  
pp. 168-176 ◽  
Author(s):  
Pui Lam Ng ◽  
Jeffery Yuet Kee Lam ◽  
Albert Kwok Hung Kwan
Keyword(s):  
Reinforced Concrete ◽  
Multilevel Analysis ◽  
Crack Opening ◽  
Full Range ◽  
Analysis Method ◽  
Concrete Frames ◽  
Range Analysis ◽  
Strength Deterioration ◽  
Rc Frames ◽  
Frame Member

Full range analysis of reinforced concrete (RC) members covering the post-crack and post-peak regimes is important for obtaining the deformation response and failure mode of structural members. When a RC member is subject to an increasing external load, the critical sections would exhibit cracking and/or softening. Due to stress relief effect in the proximity of crack opening and plastic hinging, unloading may occur at the adjacent regions. The variable stress states of discrete sections would lead to sectional variation of stiffness, which could not be accounted for by conventional structural analysis methods. In this paper, a nonlinear multilevel analysis method for RC frames whereby the frame members are divided into sub-elements and sectional analysis is utilised to evaluate stiffness degradation and strength deterioration is developed. At sectional level, the secant stiffness is determined from moment-curvature relation, where the curvature is evaluated based on both transverse displacements and section rotations of the frame member. Unloading and reloading behaviour of concrete and reinforcing steel is simulated. In implementing the multilevel analysis, secant iteration is performed in each step of displacement increment to obtain the convergent solution satisfying equilibrium. Numerical example of RC frame is presented to demonstrate the applicability and accuracy of the proposed nonlinear multilevel analysis method.

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