Seismic Retrofitting of RC Beam-Column Connections

Prof. Minakshi Vaghani, Assistant Professor, Civil Engineering Department, SCET, Surat
Designing beam–column joints is considered to be a complex and challenging task for structural engineers, and careful design of joints in RC frame structures is crucial to the safety of the structure. Although the size of the joint is controlled by the size of the frame members, joints are subjected to a different set of loads from those used in designing beams and columns. As a result, it is necessary to pay special attention to the detailing of reinforcement within a joint region. [36] It has been identified that the deficiencies of joints are mainly caused due to inadequate design to resist shear forces (horizontal and vertical) and consequently by inadequate transverse and vertical shear reinforcement and of course due to insufficient anchorage capacity in the joint. Therefore, inadequate transverse reinforcement and insufficient anchorage in the joint are two major problems of joints designed as per non-seismic guidelines [2]. These problems have been highlighted, in recent past, by the damages observed in devastating earthquakes in different countries. The two major failure modes for the failure at joints are (a) joint shear failure (Fig. 2) and (b) end anchorage failure

RC beam-column connections Joint Shear Failure
Figure 1: Terminology of RC beam-column connections
Source: Jaehong Kim et. al. 2009 [11]
Figure 2: Joint Shear Failure
Source: A. Sharma et al. (2011) [1]

In this study, a conventional four-storey RC school building (Fig. 3) is considered for analysis, design and detailing of exterior joint. Different failure modes are expected in beam-column joints depending on the type of joint (exterior or interior) and the adopted structural details. Due to sudden discontinuity of the geometry, exterior joints are found to be more vulnerable to seismic loading than the interior one because it demands to explore additional parameters such as bond-slip of reinforcement [Pampanin et al. (2003)]. Hence, in the present study, exterior beam-column joint has been chosen for investigating the performance under seismic type loading.

Graphical User Interface of STAAD
Figure 3: General Arrangement of the Building Frame Considered for the Study Figure 4: Graphical User Interface of STAAD.Pro

Characteristic compressive strength of concrete and tensile strength of steel used in the specimen have been taken as 30 MPa and 415 MPa, respectively. The specimen has the following general and cross-sectional dimensions: height of column is 3200 mm having cross-sections of (425 x 425) mm and length of beam is 2500 mm with beam size (300 x 525) mm. For casting the specimen, weight ratio of cement: sand: coarse aggregate was adopted as 1 (cement): 2.25 (fine aggregate): 2.35 (coarse aggregate-60% 10 mm size, 40% 20 mm size): 0.5 (w/c). Ordinary Portland Cement (OPC) with 28 days minimum compressive strength of 53 MPa is to be used.

Design of specimen using STAAD
Figure 5: Design of specimen using STAAD.Pro

The geometry of the components (top and bottom portion of column and beam length from joint face) is chosen to match the bending moment distribution at the joint for which it is designed. Seismic analysis (Response Spectrum Analysis) of the framed structure (Fig. 3) has been performed using STAAD.Pro to obtain the design forces. Design assumptions are mentioned in Table 1. The following provides a broad overview of the basic modelling, analysis, and design processes using STAAD.Pro.

Retrofitting of RC-Beam Column

The results obtained from the analysis of a 3 - bay four-storey RC building under the load combinations are used to design the specimen (Fig. 4). Finally, as shown in Fig. 5, the geometry of the components (top and bottom portion of column and beam length from joint face) is chosen to match the bending moment distribution at the joint for which it was designed.

Reinforcement Details of Specimen
Figure 6: Reinforcement Details of Specimen

Graphical User Interface of ATENA 3D Pre-Processor
Figure 7: Graphical User Interface of ATENA 3D Pre-Processor

In a numerical investigation, it is utmost important to provide the material properties as realistic as possible. There are many nonlinear finite element analysis programs of RC structures available. e.g. ATENA, ANSYS, Drain-2DX, MSC.MARC etc. Considering its application, effectiveness, user friendliness, availability, ATENA [1] has been selected for carrying out numerical analysis of the specimen designed for the study.

NBM&CW February 2015

Click Here
To Know More / Contact The Manufacturer
Please provide your details we will contact you as soon as possible
Please let us know your name.
Invalid Input
Please let us know your Designation.
Invalid Input
Please let us know your City.
Please let us know your State.
Please let us know your Country.
Please let us know your Contact Number.
Please let us know your email address.
Please brief your query.

Self Concrete Mixer: AJAX Soaring Up New Heights!

AJAX, a world-class leader in providing concreting business solutions, was established in 1992 for manufacturing Self-Loading Concrete Mixers. Today, it is positioned as a global leader in this product category. Over the years Read More ...

Durability of Concrete made with Marble Dust as partial replacement of Cement subjected to Sulphate attack

This experimental study presents the feasibility of the production of more durable concrete with marble dust as partial replacement of cement by 5%, 10%, 15% and 20% by weight. Standard concrete cube specimens of size 150mm×150mm×150mm Read More ...

Putzmeister Delivers 5,000th Stationary Concrete Pump

Putzmeister India recently rolled out its 5,000th Stationary Concrete Pump from its factory in Verna, Goa. Established in 2007, Putzmeister offers customers in India, Nepal, Bangladesh, Bhutan, Sri Lanka and Maldives concreting Read More ...

Upscaling the Use of Recycled Aggregate Concrete

This paper presents an overview of several aspects that can further upscale the use of recycled aggregate concrete. It presents the main steps that need to be followed to demolish existing barriers to the use of recycled Read More ...

Challenges Facing the Concrete Industry

There are still a number of challenges facing the Concrete Industry. From a political and social viewpoint, improving the sustainability of concrete construction has to be the first challenge, not because concrete solutions are Read More ...

Strength behaviour of M25 and M45 concrete incorporating accelerators and stone waste

Accelerators are used to accelerate the setting and development of concrete at early age, and also speed up the construction work for early removal of formwork. Due to depletion of natural resources, and emission of carbon dioxide during Read More ...

Durability of Concrete made with Marble Dust as partial replacement of Cement subjected to Sulphate attack

This experimental study presents the feasibility of the production of more durable concrete with marble dust as partial replacement of cement by 5%, 10%, 15% and 20% by weight. Standard concrete cube specimens of size Read More ...

Effect of Aggregate-Cement Ratio on Engineering Properties of Pervious Concrete

Pervious concrete is a composite type of material containing coarse aggregate, little or no fine aggregate, cement and water. In pervious concrete, carefully controlled amount of water and cementitious materials are used to Read More ...

Recent Advances in - Self-Compacting Concrete

In line of advanced concrete technology and research self-compacting concrete (SCC) contribute an innovative role for the development and its implementations worldwide. SCC, also known as self-leveling concrete Read More ...

Life-Cycle Management of Concrete Structures

A concrete structure is required to maintain its functions and performance during its design service life. However, serious damages have been sometimes found, which may be caused by physical and chemical actions. Read More ...

Green, Sustainable Construction: Solutions for Affordable Housing

Concrete is the second most consumed material in the world after water and it is used most widely in the construction industry due to its high compressive strength and other properties.[1] Therefore, the basis of Read More ...

Aesthetical Integration in High Performance Concrete for Infra Construction

Concrete, the wonder material that has shaped our surroundings, was invented in the mid-18th century, and continues to be the most widely used construction material. Concrete came to architects and designers as a boon Read More ...

Comparative Study of concrete mix design using IS and ACI methods with and without super-plasticizer

Concrete is a composite material consisting of cement, water, and aggregates. These ingredients can be mixed in different ratios to attain desired strengths. Though rough mix ratios for different strengths Read More ...

Non destructive testing for determining the strength of concrete

Civil engineering infrastructures are designed to operate for long periods of time, such as 50 to 100 years. However, several unpredictable and uncontrollable factors reduce their expected performance and life Read More ...

An Experimental investigation on utilizations of Marble Dust as partial replacement of Cement in Concrete

Marble dust is an industrial by-product obtained during sawing, shaping, and polishing of marble and causes a serious problem to the environment. Research indicate that the effect of mixing marble dust on the Read More ...

Use of Ferrocement for Construction of Mini Check Dams and Diversion Structures

Diversion structures and check dams are constructed for diverting/ storing the water, flowing in shallow rivers/ streams for various purposes. The present practice is to use brick / stone / stone block masonry Read More ...
NBM&CW

New Building Material & Construction World

New Building Material & Construction World
MGS Architecture

Modern Green Structures & Architecture

Modern Green Structures & Architecture
L&ST

Lifting & Specialized Transport

Lifting & Specialized Transport
II&TW

Indian Infrastructure & Tenders Week

Indian Infrastructure & Tenders Week