Seismic Assessment of Existing Gravity Load-Designed RC Framed Building

https://doi.org/10.22214/ijraset.2023.48836

ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.538

Volume 11 Issue I Jan 2023- Available at www.ijraset.com

Seismic Assessment of Existing Gravity LoadDesigned RC Framed Building

1PG Student, 2Project Guide, Department of Civil Engineering, G H Raisoni Institute of Engineering and Technology, Nagpur, India

Abstract: Reinforced concrete frames designed with early seismic codes, or sometimes without seismic codes, tend to be low and in most cases have limited ductility. Very often the details are poor and therefore the critical zones do not behave flexibly and have delicate failure mechanisms. Because of these problems, the evaluation of existing reinforced concrete (RC) structures requires a complex procedure. A summary of the models that allow the analysis of the nonlinear behavior of RC structures is discussed. An innovative numerical model is presented that takes into account the main mechanical phenomena influencing the nonlinear behavior of RC frames. Finally, the influence of different force and deformation sources on the global behavior of existing buildings is investigated and the necessary features of numerical models are pointed out.

Keywords: Seismic assessment, Gravity Load, RC Framed etc.

I. INTRODUCTION

Earthquakes are natural phenomena that occur in many places around the world. Strong earthquakes near populated areas have caused large casualties and property damage. Although advances have been made in earthquake forecasting, earthquakes cannot be accurately predicted in terms of timing, strength, or location. Therefore, the main way to reduce losses is to build earthquakeresistant structures.

This is evident from past earthquakes in India such as Manipur (2016), Nepal (2015), Sikkim (2011), Kashmir (2005), Bhuj (2001), Chamoli (1999), Jabalpur (1997) and Latur (1993). ), that all types of buildings can be damaged if they are not properly designed. It has been reported in the literature that more than 90% of the casualties in earthquakes in India are due to the collapse of many commercial and residential buildings.

Often, a concrete structure fails to meet its design time due to material deterioration, unexpected loads, physical damage, or faulty construction. Sometimes there are changes in the intended use of the building, such as the conversion of a residential building into a commercial building for which it was not originally designed. It is often proposed to add new floors to an existing structure, which can significantly affect the subfloor and foundation. Every few years, new analysis codes and design codes are introduced for which many existing structures are not designed. Modernization is often required to bring these existing structures in line with current codes of practice.

This behavior mimics the current scenario of existing RC buildings in this location, which must be properly reinforced. The analysis found that the RC building was exposed to seismic forces and required renovation to remain useful during its service life.

II. PROBLEM DEFINITION

A gravity loaded RC frame building constructed before 2002 is not designed for seismic forces. Demolition of such a structure built before 2002 and construction of a new structure can be expensive, therefore this project will analyze each structure and renovation part that will break and make the existing gravity-loaded RC frame building withstand the force of an earthquake

Because earthquake is. a natural phenomenon and cannot be accurately predicted, therefore buildings designed and built without considering seismic forces are vulnerable to earthquakes and can cause human casualties and damage infrastructure.

III. PROPOSED SYSTEM

The structure involved in this project is G 3 RCC Building, Shapoorji Complex, Kazipet, Warangal, Telangana, India. The building was designed in 2000 and built in 2002. The design was based solely on the gravitational load, without considering the effect of the earthquake. Recently it was proposed to upgrade this building to G5 by adding two floors to the existing building. This time the effect of the earthquake must also be taken into account. Since Warangal is located on the border of zone II and III, the structure must be designed for both zones and compare the results.

Mr Ritesh Jamaiwar1, Prof. Prajwalita Thamke2

ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.538

Volume 11 Issue I Jan 2023- Available at www.ijraset.com

This project prepares 6 separate models, 3 for model G 3 and 3 for model G 5. Project considering only gravity loads, earthquake design for zone II and seismic design for zone III and results for each. . must be considered for both G 3 and G 5 buildings. The safety of the G 5 building must be checked for earthquake loads in both zones. If any part fails under an earthquake load of G 5, renovation strategies must be decided to make the building safe under current conditions.

IV. OBJECTIVE

The objectives of the proposed work are as follows:

1) Modeling and analysis of G 3 existing RC frame building before and after adding the last two floors in SAP-2000.

2) Reinstallable critical part resists earthquake forces.

3) Compare the behavior of structures according to earthquake zones 2 and 3.

V. LITERATURE REVIEW

K Rama Raju and others. to [1] Assessing the capacity of an existing building according to current operational guidelines is an important task of performance-based assessment. To improve the performance of existing buildings, there is an urgent need to accurately assess the actual lateral load resistance and possible failure modes according to the current regulations for resilient design and renovation or renovation system design. A simplified three-parameter model is used to find the stress-strain curves of RC elements outside the yield zone of confined concrete. Nonlinear static analysis is used to study the performance of structural components at target building levels.

Hyunsu Seo et al. [2] Seismic retrofit technology has been significantly developed to reduce building damage during earthquakes. The minimum number and location of the seismically reconstructed reinforced concrete columns of the school buildings used in this study were derived using an optimization technique. A time-history dynamic analysis of a column-and-beam frame structure is performed using a three-dimensional finite element model to obtain empirical results.

Aditya Singh Rajput and others. to [3] Studies have been made to restore the seismic performance of corroded reinforced concrete (RC) columns. The renovation materials consist of High Performance Fiber Reinforced Concrete (HPFRC) and Glass Fiber Reinforced Polymer (GFRP). The performance of the column specimens was evaluated based on the most important parameters of strength and durability. The corroded specimen, when retrofitted with only the HPFRC sheath, produced satisfactory strength and durability compared to the uncorroded sublimated column, but had lower strength compared to the seismically designed column specimen. Packing of the GFRP laminates further improved the response of the specimens in terms of strength and ductility parameters. The energy absorption of the upgraded pillars has recovered satisfactorily.

Ryotaro Kurosawa et al. al [4] Describe a prestressed concrete frame system with lightweight compression joints used for seismic retrofitting of existing reinforced concrete frames. To investigate the hysteretic behavior and damage characteristics of frames, cyclic loading tests are performed on prestressed concrete elements and cast-in-place reinforced concrete frame assemblies. The test results show the damage tolerance of precast frames in terms of well-controlled cracks and minimized residual movement compared to monolithic RC frames. A simplified numerical model is introduced to simulate the hysteretic behavior of lightweight compression joints. In the proposed method, the dynamic seismic response of the renovated prototype building is analyzed using numerical analysis. We compare two renovation plans with different fixed prefabricated frames. The results indicate that the partial renovation of some of the lower floors, which is common in Japan, may cause drift to concentrate on the upper floors of Building

G. Navya and Pankaj Agarwal et al. to [5] reported in the study states the complete modernization process of a building designed with two different philosophies ie. IS 56: 2000 and IS 1893 (Part 1): 2002 with modernized steel braces. A fragility analysis was also carried out to show the probability of damage in different rooms, which will be significantly reduced after the modernization of the building.

A. Shuraim and A. Charif et al. al [6] In this work, a non-linear static analysis procedure was applied to analyze the existing design of a reinforced concrete frame to investigate the applicability of thrust force in the design evaluation of new buildings. For comparison, the potential structural deficiencies of the frame were evaluated using the seismic resistance code and thrust method. In the first approach, potential deficiencies were determined by remodeling one selected seismic combination to show which parts needed additional strengthening. In another approach, a thrust analysis was performed to evaluate the seismic performance of the frame and identify the location of the plastic hinges. The work shows that the vulnerable areas revealed by the two procedures are significantly different, with the latter method tending to overestimate column strength, thus masking earlier detection of column weaknesses. The work provides rational explanations for the apparent contradiction that can be taken into account to apply the push method to the design or evaluation of new buildings.

ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.538

Volume 11 Issue I Jan 2023- Available at www.ijraset.com

Mehmet Inel and Hayri Baytan Ozmen et. to [7] This article investigates the possible differences in impulse analysis results due to default and user-defined nonlinear component properties. Four and seven-story buildings are considered typical for this study. Plastic hinge length and transverse reinforcement spacing are assumed to be effective parameters for user-specified hinge properties. Observations show that the length of the plastic hinge and the spacing of the transverse reinforcement do not affect the shear capacity of the base, while these parameters significantly affect the transfer capacity of the frames. The comparisons show that increasing the transverse reinforcement improves the shear capacity. The results clearly show that the user-defined hinge model is better than the default hinge model in reflecting the nonlinear behavior consistent with the element properties. However, if the default hinge model is better for simplicity, the user should be aware of the functions that the program provides and avoid abusing the default hinge functions.

Ayman Abd-Elhamed and Sayed Mahmoud et. al [8] This paper presents a nonlinear static analysis using numerical simulations to evaluate the performance of a 12-story Rc moment-resisting frame building in Cairo. The analysis is first performed using the equivalent static force technique as the first step. In the second and main stage of the analysis, a non-linear static thrust analysis is performed. The results of the study showed that properly designed buildings perform well at the appropriate seismic load level for the Cairo zone, where the building clearly behaves as a strong column-weak beam mechanism. However, when an unexpected seismic acceleration load overwhelms Cairo, the building appears to be vulnerable and in need of reinforcement, with the formed plastic hinges exposed to dangerous levels. Plastic hinges formed against shear in poorly designed buildings have been found to cause non-plastic failure even at vibration levels suitable for the Cairo zone.

Lipika Haldera and Santanu Paul et. to [9] The objective is to assess the seismic vulnerability of a low Rc frame building designed for gravity loading according to Indian codes. Non-linear static analysis is performed to find the bearing capacity curve of the building. Fragility analysis is used to develop a fragility curve for different damage categories based on the HAZUS methodology.

Damage Probability Matrices (DPMs) are formed for two different earthquake hazard levels, i.e., the largest earthquake to be considered and the design-based earthquake, depending on the performance point, to compare the damage status of each hazard level. The result shows that the damage of the considered building varies from moderate to severe damage condition to different seismic hazard level.

Ravikumar et al. to [10] This article tried to study two types of irregularities in building models, namely plan irregularities with geometric and membrane discontinuities and vertical irregularities with dips and sloping bottoms. These irregularities are created as per clause 7.1 of IS 1893 (part1) 2002 code. In order to identify the most vulnerable building of the studied models in Oder, different analytical approaches are made to identify the seismic demands in both linear and non-linear ways. In addition, the effects of three different lateral loads on the performance of various irregular buildings are investigated in a thrust analysis.

Y. Fahjan et. to [11] presented a numerical modeling technique used to represent the physical behavior of structural elements such as frame and shear walls, and it becomes the most important issue in the design process. The nonlinear behavior of shells is usually modeled with a multilayer shell element using a layered material model. In this approach, the concrete and reinforcement in the structural parts are modeled in different layers, respectively. This paper evaluates and comments on the consistency of different approaches to nonlinear shear wall modeling in practice. For this, 3-, 5-, and 7-story reinforced concrete (RC) frames with shear walls are analyzed using a two-dimensional nonlinear finite element method under constant gravity and gradually increasing lateral loads. The analysis results of these models are compared according to the general behavior of the structural systems. In addition, the definition of plastic hinge properties is discussed, which strongly affects the prediction of RC wall capacity curve in thrust analysis.

Sameh A and El-Betar et al. to [12]. buildings in Egypt. Seismic evaluation was applied to two selected case studies, one representing GLD buildings and the other representing buildings designed according to the Egyptian code. In addition, a push analysis was performed to determine the vulnerability of these buildings.

Ashim Adhikai et al. to [13] This article presents an assessment of the seismic capacity of typical low and medium-rise reinforced concrete buildings in Nepal. The nonlinear behavior of nine residential buildings was investigated. Structural performance is represented by strength, stiffness, load capacity curves, and story deflections. The construction models were analyzed as bare frames and the drift profiles were compared with some standard creep limits to describe the vulnerability. After the analyses, the buildings identified as vulnerable were modernized using the column cladding technology and elemental analyzes were performed again. Seismic characteristics of prepared and reconstructed buildings were compared. The sum of the observations shows that the column size directly affects the vulnerability of buildings. In addition, the column envelope significantly improves the seismic performance of low and medium RC buildings, as shown in a comparison of thus constructed and renovated structures based on interstory drift and base period.

ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.538

Volume 11 Issue I Jan 2023- Available at www.ijraset.com

VI. BLOCK DIAGRAM

VII. WORKING METHODOLOGY

Weaknesses in the structural system of existing RC buildings and deficiencies in steel structure reinforcement can affect the failure modes, which directly affects the ability of the RC building to withstand loads and remain stable. The seismic vulnerability of a building is usually expressed as a ratio of intensity measurements. In this work, a general methodology for seismic resistance assessment of an existing RC building is introduced to withstand the seismic loads associated with Zone 3 requirements. Seismic vulnerability assessment is usually done either qualitatively or quantitatively using certain empirical methods, namely rapid visual screening methods and the P25 scoring method followed by non-destructive testing (NDT). Seismic strengthening/upgrading is done as per BIS 15988:2013 and IITK-GSDMA guidelines for seismic evaluation and strengthening of buildings and CPWD manual. Due to the importance of the structure, this qualitative evaluation is usually followed by an analytical evaluation used in seismic design. In this work, a field visit is made, where the building plan collected using the existing structural units is checked. To understand visual signs of damage, decay, etc., a visual inspection is performed by walking around the building, followed by a non-destructive impact hammer test to confirm the compressive strength of the structural elements. This input is used to develop an analytical model of the existing G 3 and proposed G 5 RC building structure using SAP2000 software. Seismic strengthening and retrofitting of RC buildings using several approaches have been described in the literature. A similar study on retrofitting a gravity-loaded RC building using external concentric steel bracing systems with SAP2000.

VIII. CONCLUSION

Submitted Critical Review In this project, we analyze a building that was not designed and constructed with earthquake loads in mind. Modeling and analysis of G 3 existing RC frame building before and after two upper story additions in SAP-2000. This can be used to outline some of the properties that a numerical model should provide to obtain a reliable estimate of the seismic capacity of underdesigned buildings. Details are often poor (ie low percentage of transverse reinforcement, poor bonding conditions); it specifies that critical zones (ie, beam-to-column joints, column bottom zone) do not behave plastically and exhibit brittle failure mechanisms (ie, pullout or buckling of rebars, shear failure, etc.). The above-mentioned problems cause many problems in evaluating the seismic capacity of RC frames. In general, all decay sources are potentially active, which can increase the difficulty of all stages of seismic evaluation.

REFERENCES

[1] Earthquake Disaster Risk Index Report (2019) A publication of the National Disaster Management Authority, Government of India. National Disaster Management Authority, New Delhi

[2] IS 1893 (2020) Criteria for earthquake resistant design of structures. Part 1 general provisions and buildings. Bureau of Indian Standards, New Delhi.

[3] IS 1893 (2016) Criteria for earthquake resistant design of structures. Part 1 general provisions and buildings. Bureau of Indian Standards, New Delhi.

[4] Oggu P, Kumar VK, Gopikrishna K (2016) Seismic fragility analysis of vertical setback RC structures. In: Proceedings of the international conference on the trends and recent advances in civil engineering (TRACE-2016), 11–12 Aug 2016, Amity University, Noida, India.

Fig.1. Block Diagram of system

International Journal for Research in Applied Science & Engineering Technology (IJRASET)

ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.538

Volume 11 Issue I Jan 2023- Available at www.ijraset.com

[5] Oggu P, Gopikrishna K (2017) Seismic behavior and its infuence on damage probabilities of irregular R.C. buildings. In: Proceedings of the international conference on composite materials and structures-ICCMS 2017, 27–29 Dec 2017, Hyderabad, India.

[6] Pisode M, Surana M, Haldar P, Singh Y (2017) Comparative assessment of seismic fragility of RC frame buildings designed for older and revised Indian standards. ISET J Earthq Technol 54(1):17–29.

[7] Gautham A, Gopikrishna K (2017) Fragility analysis a tool to assess seismic performance of structural systems. Mater Today Proc 4(9):10565–10569.

[8] Oggu P, Mehulkumar P, Gopikrishna K (2019) Infuence of real ground motion records in performance assessment of RC buildings. Int J Eng 32(12):1745–1752.

[9] Oggu P, Gopikrishna K (2020) Assessment of three-dimensional RC moment-resisting frames under repeated earthquakes. Structures 26:6–23.

[10] IS 15988 (2013) Seismic evaluation and strengthening of existing reinforced concrete buildings guidelines. Bureau of Indian Standards, New Delhi.

[11] Rai DC (2015) Seismic evaluation and strengthening of existing buildings. IIT Kanpur and Gujarat State Disaster Mitigation Authority, Gandhinagar.

[12] CPWD (2020) Handbook on repair and rehabilitation of RCC buildings. Central Public Works Department, Government of India, New Delhi.

[13] Masi A (2013) Seismic vulnerability assessment of gravity load designed R/C frames. Bull Earthq Eng 1(3):371–395.

[14] Zhang Y, Hu X (2021) Seismic retroftting of reinforced concrete frame structures using GFRP-tube-confined-concrete composite braces. Earthq Eng Eng Vib 11(1):91–105

[15] Li G, Jiang Y, Zhang S, Zeng Y, Li Q (2015) Seismic design or retroft of buildings with metallic structural fuses by the damagereduction spectrum. Earthq Eng Eng Vib 14(1):85–96