‘Effect of Using Different Concrete Strengths for Columns and Beams on The Behaviour of Building Frames’ (original) (raw)
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EFFECT OF USING HIGH STRENGTH CONCRETE COLUMNS ON THE STRUCTURAL BEHAVIOUR OF R.C BUILDINGS.
Strength, durability and stability are the main criteria for material selection and design in the construction industry. Consequently, development and enhancement of construction materials is always an active and attractive field for engineers and researchers. Elevated temperature (fire) is a potential threat for any structural buildings that can cause a major damage. Response of construction materials exposed to elevated temperature or fire requires a full study and analysis with lessons learned from previous cases. High strength concrete (HSC) has been used in the lower story columns of high rise buildings owing to its qualities over normal strength concrete (NSC) in many countries. But, the full structural qualities of the HSC were unable to be used because of insufficient information regarding the structural behaviour of the material and its properties. Columns moment-curvature curves were developed and maximum inter story drifts were obtained for the different frame models with variation in columns concrete strength. The study shows that frames with HSC columns have got lower stiffness and performed well in satisfying ductility demand. The maximum inter storey drifts are slightly higher for frames with HSC columns, but the contribution of the concrete strength in resisting the lateral deformations was significant. Economic comparisons were also made and it was found that the most economical frame corresponds to frame with the highest columns concrete strength.
Effect of using High Strength Concrete Columns on the Structural Behaviors of Building Frame
2014
High strength concrete (HSC) has been used in the lower story columns of high rise buildings owing to its qualities over normal strength concrete (NSC) in many countries. But, the full structural qualities of the HSC were unable to be used because of insufficient information regarding the structural behavior of the material and its properties were not adequately addressed in building codes including EBCS. Analytical study was conducted at structure level to investigate the effect of using HSC column on the structural behavior of regular models of medium to high rise frame buildings under seismic lateral load in addition to gravity loads. Concrete strength variations of C30 to C90MPa were applied on the columns of the frame models. The proposed properties of the HSC class were incorporated in the analysis and design of the columns. The frames analysis was done using ETABS and columns were designed based on the EBCS column design procedure.
Design Criteria For Reinforced Concrete Columns Under Seismic Loading
2013
After the devastating Bhuj earthquake, the seismic design of structures is becoming more important. Earthquake induced motion is one of the sources of dynamic loads, that must be considered in the design of structures. The revised code IS 1893-2002 (Part 1) has reclassified the zonal map of India into four zones, thus bringing more than 55% of the area under seismic zones. An attempt has been made in this paper to study the behaviour of interior columns of multistoried building frames in various seismic zones. In normal practice, the interior columns of a symmetric building are designed only for axial loads using IS 456:2000 with a minimum eccentricity. But during earthquakes, higher moments are generated in these interior columns and there is no provision in IS 1893-2002 for the eccentricity to be adopted in the design of columns. Several multistoried building frames were analysed using STAAD Pro and the eccentricities of loading in the interior columns were calculated. Based on the study, suitable equations were developed for each seismic zone to calculate the eccentricity of an interior column in symmetric buildings. This eccentricity can be adopted as the design criterion for the seismic design of interior columns.
Effect of Column to Beam Strength Ratio on Performance of Reinforced Concrete Frames
A ductile reinforced concrete structure shall be designed to ensure that plastic hinges occur as many as possible before collapse. This paper investigates the effect of column to beam strength ratio on performance of ductile reinforced concrete buildings. Fourteen interior frame models of two building categories which are five and ten stories buildings were modeled and analyzed. The main parameter among those models is column to beam strength ratio of 1.0 to 2.0 which are 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0. The values are the ratio between column nominal strength (∑M nc) and beam nominal strength (∑M nb). In this study, the ratio between column strength to beam probable strength (∑M prb) of 1.2 is also investigated. A static nonlinear pushover analysis was used to evaluate the performances of all models. Analysis results show that all models have a life safety performance level. A collapse mechanism of beam sway mechanism was achieved for strength ratios of 1.4 to 2.0 for five story frame models and 1.6 to 2.0 for ten story frames. The increase in the strength ratio up to 1.4 can increase ductility factor significantly, however, beyond that the strength ratio does not affect the ductility both for five and ten story frame models. Considering the ratio between column strength to beam probable strength of 1.2, the ductility factor increases by 16% and 25% respectively for five and ten stories, however, both frames still have performance level of life safety and collapse mechanism of column sway mechanism.
Ernst & Sohn ce/papers 6 , 2023
Usable/rentable floor areas are crucial for the building owners in reinforced concrete (RC) tall buildings. To address this issue, concrete-encased (CE) or concrete-filled (CF) composite columns are proposed as alternative vertical load carrying elements by providing the required strength and ductility, but with smaller dimensions. Comparing the performance of columns with different configurations can be done using moment (M)-axial load (N) interaction curves. This paper summarizes the approaches proposed by Eurocode 4 and AISC 360-16 for both types of composite columns, presenting simplified and true curves for a specific class of sections. Two case studies involving hybrid RC tall buildings in Istanbul, which utilized composite columns, are presented along with a comparison with steel-concrete composite and RC solutions. Numerical results indicate that employing steel-concrete composite columns resulted in approximately 24% reduction in total cross-sectional areas for one of the case studies, leading to increased usable/rentable areas. Additionally, concrete-encased and concrete-filled composite columns exhibited similar performance in terms of axial load-moment capacities. The impact of longitudinal rebar ratios is also investigated, revealing that the AISC 360-16 approach yields smaller bending moments and compression capacities compared to Eurocode 4 due to the significant strength reduction factor considered in calculating the concrete contribution in composite sections.
Seismic performances of reinforced concrete frames with wall-like columns
The IES Journal Part A: Civil & Structural Engineering, 2009
In regions of low to moderate seismic risk, such as Singapore and Malaysia, buildings with relatively weak lateral structural resisting systems are likely to be common. Although ground motions because of long distance earthquakes centred in Sumatra have occurred, there has been no record of earthquake damage in this region. This article compares the results obtained from pushover analyses of six-storey reinforced concrete (RC) frames with experimental observations. The experimental observations of four internal beam-column joints, which were designed according to BS 8110, were summarised. From this, we address the performance of some typical RC frame structures under low seismic loading. By adding about 0.075% of hoop reinforcement in the beam-column joints, one can improve the seismic performance of the frame in the weak direction more significantly than in the strong direction. Also, relatively large joint shear input during low to moderate earthquakes can result in diagonal tension cracking and the building may likely be governed by joint shear failure.
‘Seismic Behavior of Beam-Column Connections in High Strength Concrete Building Frames’
This paper presents, an analytical study carried out on High Strength Concrete (HSC) building frames using a nonlinear dynamic analysis computer program (IDARC-M). The program was originally developed for the analysis of normal R.C. frames and it was modified to predict the response of HSC frame structures. Unlike most of conventional investigations into HSC beam-column connections, this work considers such connections as integral part of the studied ten-story HSC frame. The inelastic behavior of an interior beamcolumn connection in the first floor was studied. It was found that the use of HSC improves column capacity, enlarges rigidity of beam-column joints, reduces the effect of lateral reinforcement distribution in beams and columns, and decreases the fundamental natural period of the frame. The type of column support at foundation level has a great effect on the drift of the studied building frame.
“Seismic Analysis of Multi-Storey Buildings with Composite Columns and RCC Beams”
Journal of emerging technologies and innovative research, 2020
In this work, a study was conducted on the behavior of composite columns, which are called reinforced concrete columns (SCC). The structure is exposed to a zone 5 seismic load according to IS 1893: 2016 and combinations of dead loads have been considered. The results of the bending moment and the lateral deformation of the frame are compared with the SAP 2000 software. In this study, an analysis of the two-span structure with a composite column with a seismic zone five according to IS 1893: 2016 was carried out and a comparison was made between bending moments, section modulus, deflections, shear force for seismic load and dead load.
Strength and drift demand of columns of RC framed buildings with soft ground story
2009
Earthquakes occurred in recent days reveals the fact that soft storied masonry infilled RC frame buildings are more fragile. In this paper an extensive computational study has been conducted to find out the behavior of such buildings as well as their seismic vulnerability. Finite element models of a few typical multistoried buildings have been subjected to response spectrum as well as equivalent static earthquake loading. Infills on upper floors have been modeled as diagonal struts keeping the ground floor free of infill. Response spectrum analysis shows that the total base shear in buildings as well as design column shear and moments on open ground floor are significantly magnified in presence of infill on upper floors. Study of the sway characteristics shows that the columns of open ground floor demand significantly higher flexibility and ductility. Conventional equivalent static force method is incapable of predicting these behaviors resulting in significant under-design of the c...
Seismic behaviors of columns in ordinary and intermediate moment resisting concrete frames
Engineering Structures, 2005
The objective of this study was to investigate the seismic behaviors of columns in Ordinary Moment Resisting Concrete Frames (OMRCF) and Intermediate Moment Resisting Concrete Frames (IMRCF). For this purpose, two three-story OMRCF and IMRCF were designed according to the minimum design and reinforcement detailing requirements specified in ACI 318-02. This study assumed that the building was located in seismic zone 1, as classified by UBC. According to ACI 318-02 the reinforcement detailing requirements for OMRCF are less stringent than those for either IMRCF or SMRCF (Special Moment Resisting Concrete Frames). Tests were carried out to evaluate the seismic behaviors of OMRCF and IMRCF columns using 2/3 scale model columns. Each column was considered as consisting of an upper part and lower part divided at the point of inflection. Quasi-static reversed cyclic loading was applied to the specimens with either constant or varying axial forces. The test variables of this experimental study were the type of axial force (constant and varying, and low and high), the existence of lap splices (with or without lap splice) and type of moment resisting concrete frame (OMRCF or IMRCF). It was observed that all OMRCF and IMRCF column specimens had strength larger than that required by ACI 318, and they had drift capacities greater than 3.0% and 4.5%, respectively. However, the drift capacity of specimens varied with respect to the existence of lap splices and the spacing of lateral reinforcement at column ends.