scholarly journals Distribution of load effects and reliability of reinforced concrete frames: intact and with columns removed

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Pedro Henrique Preto Facholli ◽  
André Teófilo Beck
Keyword(s):  
Reinforced Concrete ◽  
Rc Beams ◽  
Concrete Frames ◽  
Rc Frames ◽  
Frame Buildings ◽  
Load Effects ◽  
Bending Loads ◽  
Element Type ◽  
Rc Frame Buildings ◽  
Different Parts

abstract: The design of reinforced concrete (RC) frames is made on a member-by-member basis. Similarly, in the literature, the reliability of RC beams and columns is often studied in isolation from the rest of the structure. Yet, in the construction of regular frames, symmetry and regularity are often exploited, resulting in the same design for each element type. This is despite of different load effects on different parts of the structure, which leads to significant variations in the failure probability of the elements. Hence, in this paper, we investigate the reliability of members and the distribution of load effects in regular RC frame buildings, considering intact and column loss cases, where symmetry is lost. Results show that the ratios of normal-to-bending loads change significantly along building height, and this has a significant impact on reliability of individual columns.

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.

scholarly journals Performance of RC frames in 26.11.2019. Albania earthquake: Effects of irregularities and detailing

2021 ◽  
Vol 64 (3) ◽  
pp. 207-213
Author(s):  
Ivan Milićević ◽  
Marko Marinković ◽  
Nikola Blagojević ◽  
Svetlana Nikolić-Brzev
Keyword(s):  
Earthquake Engineering ◽  
Rc Frame ◽  
Flexible Systems ◽  
Rc Frames ◽  
Seismic Force ◽  
Frame Buildings ◽  
Frame System ◽  
Rc Frame Buildings ◽  
Earthquake Effects ◽  
Global And Local

The collapse and damage of large number of buildings during the November 26, 2019 (Mw 6,4) Albania earthquake caused 51 fatalities and injuries to at least 910 people. Most of collapsed or heavily damaged buildings were RC frame buildings. Although RC frame system is considered as very ductile seismic force-resisting system, its behaviour during earthquake highly depends on: (1) regularity in plan and elevation, and (2) global and local ductility. Based on the authors' visit to the earthquake-affected area on behalf of the Serbian Association of Earthquake Engineering and observations of collapsed and damaged buildings, it was concluded that among main reasons for underperformance of these flexible systems were inadequate analysis of interaction between infill walls and RC frames and reinforcement detailing of RC members.

Quantifying the Reduction in Collapse Safety of Main Shock–Damaged Reinforced Concrete Frames with Infills

2017 ◽  
Vol 33 (1) ◽  
pp. 25-44 ◽  
Author(s):  
Henry V. Burton ◽  
Mayank Sharma
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Main Shock ◽  
Limit State ◽  
Incremental Dynamic Analysis ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Frame Buildings ◽  
Story Drift

A performance-based methodology is presented to quantify the reduction in collapse safety of main shock–damaged reinforced concrete frame buildings with infills. After assessing their collapse safety in the intact state, the residual collapse capacity following main shock damage is evaluated by conducting incremental dynamic analysis to collapse using main shock–aftershock ground motion sequences. The median collapse capacity and conditional probability of collapse for the main shock–damaged building, normalized by that of the intact case are the metrics used to measure the reduction in collapse safety. Taller buildings with built-in soft and weak first stories have the highest reduction in collapse safety as a result of main shock damage. Among the engineering demand parameters recorded during the main shock analyses, story drift demands (peak transient and residual) and infill strut axial deformations have the highest correlation with the decline in collapse performance. The results of the main shock–aftershock incremental dynamic analysis to collapse are used to develop fragility functions for the limit state defined by the building being structurally unsafe to occupy.

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.

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 Rapid assessment of peak storey drift demands on reinforced concrete frame buildings

2019 ◽  
Vol 52 (3) ◽  
pp. 109-118
Author(s):  
Timothy J. Sullivan
Keyword(s):  
Reinforced Concrete ◽  
Linear Time ◽  
Rapid Assessment ◽  
Time History ◽  
Seismic Assessment ◽  
Rc Frame ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Frame Buildings ◽  
Rc Frame Buildings

The peak storey drift demands that an earthquake imposes on a building can be assessed through a detailed engineering seismic assessment or recorded if a building is instrumented. However, for the rapid seismic assessment of a large number of buildings, it is desirable to have a simplified means of estimating storey drift demands. Consequently, this paper proposes a simplified means of quickly estimating storey drift demands on reinforced concrete (RC) frame buildings. Expressions for peak storey drift demand as a function of ground motion intensity are developed by utilising concepts and simplifications available from displacement-based seismic design and assessment methods. The performance of the approach is gauged by comparing predicted storey drift demands with those obtained from rigorous non-linear time-history analyses for a number of case study buildings. The promising results suggest that the approach proposed will be useful for rapidly assessing the likelihood of damage to a range of drift-sensitive elements in modern RC frame buildings.

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.

EFFECTS OF RANDOMLY DISTRIBUTED INFILL ON COLUMNS OF REINFORCED CONCRETE FRAMES WITH SOFT GROUND STOREY

2010 ◽  
Vol 10 (03) ◽  
pp. 555-569 ◽  
Author(s):  
SHAHRIAR QUAYYUM ◽  
ISLAM MOHAMMAD NAZMUL ◽  
MOST. MAHBUBA IASMIN ◽  
KHAN MAHMUD AMANAT
Keyword(s):  
Reinforced Concrete ◽  
Response Spectrum ◽  
Base Shear ◽  
Concrete Frames ◽  
Natural Period ◽  
Rc Frames ◽  
Axial Forces ◽  
Open Ground ◽  
Seismic Loadings ◽  
Structural Responses

Reinforced concrete (RC) frames with an open ground floor and various infill distributions have been analyzed for seismic loadings by the finite element method. The infills have been modeled by diagonal struts. Focus is placed on the effects of infill distribution on various structural responses, including (i) the lateral deflection, (ii) the column axial forces, (iii) the column bending moments, (iv) the base shear, and (v) the natural period of the frame. The equivalent static force method (ESFM) and response spectrum method (RSM) for linear structures have been applied, and the results obtained have been compared. It was found that the structural responses do not change appreciably by the ESFM analysis for random infill distributions, while they increase noticeably in the RSM analysis. This manifests the inadequacy of using the ESFM for general purposes, for which modifications were proposed in this paper for the design of RC columns. As the natural period of the RC frame converges with the code equations only for higher amounts of infill, it is necessary to incorporate the amount and distribution of infill in the dynamic analysis of RC frames.

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