In earthquake-prone regions, steel structures are considered to be one of the best choices due to inherent material properties in terms of homogeneity and ductility. In the conventional seismic design of steel structures, prevalent specifications recommend that the column and joints should be strong enough such that the inelastic action or damage occurs in the beams in lateral load resisting frames. By following these design provisions, structural collapse can be prevented in the event of severe earthquakes to ensure occupant safety. However, repair and rehabilitation of damaged primary members is a challenging task and also time-consuming process, resulting in severe inconvenience to the occupants. To simplify the repair works in earthquake resistant steel structures after the event of severe earthquakes, recent research work is concentrated on designing structures to have localized inelastic damages at intended locations, which will dissipate the seismic energy and can be easily replaced after the event of a strong earthquake, so that normal life of the occupants can be restored immediately with lesser cost of repair. This paper presents a critical review of the state-of-the-art related to steel lateral load resisting systems comprising of replaceable fuses that help in the easy repair of steel structures following strong earthquakes.

Replaceable Fuses in Earthquake Resistant Steel Structures: A Review

This paper presents an externally reinforced I-beam-to-box-column seismic connection. An inclined rib-plated collar-plated configuration with web plates is used to ensure planar continuity between I-beam and box-column webs; the rib plates, inclined in plan between the beam web and the two column web planes, along with collar-plates encircling the box-column at beam flange levels and web plates in plane with the rib plates at the beam web level constitute the new configuration. This connection configuration relieves stresses on box-column flanges and helps in force transfer to the box-column webs. Performance evaluation of the proposed connection configuration shows that sufficient inelasticity is mobilized in the beam away from the column face with connection elements and welds remaining elastic. The seismic performance of the proposed connection is also found to be better than two state-of-the-art connection schemes in terms of higher strength, stiffness, and higher reserve strength of the welds under cyclic displacement loading.

Externally Reinforced Welded I-Beam-to-Box-Column Seismic Connection

Energy dissipative beam-column connection for earthquake resistant moment frames

ARTICLE INFO Article history: Received: January 2017. Revised: May 2017 Accepted: June 2017.

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Finite element analysis of a rigid beam to column connection reinforced with channels

The government is taking the leading role to persuade the construction industry to engage a more systematic approach and methodology in construction by adapting the Industrialized Building Systems [IBS]. Wall-slab structural system is an IBS system which is suitable for use in residential building. Moment transfer of joint is an important aspect for proper structurally functioning of wall-slab system. Hence, the main aim of this study is to investigate the effect of reinforcement details in the wall on bending capacity for support stiffness in wall-slab system for residential project in Malaysia. A total of six wall specimens were tested. Three of this specimens consisted single layer of rebar while another three specimen consisted of double layer of rebar. The size of the wall-slab's specimens is 1000 mm in length [L], 1080 mm in width [W], 1000 mm in height [H] and 80 mm in thickness [T]. The average concrete strength Grade 30 N/mm2 and the average yield strength of R5 bar was 817 MPa. The bending capacity at failure for single layered of rebar in wall for specimen 1, 2 and 3 were found to be 3.59 kNm, 3.81 kNm and 3.15 kNm, respectively. The bending capacity at failure for double layered of rebar in wall for specimen 1, 2 and 3 were 5.50 kNm, 6.31 kNm and 7.00 kNm, respectively. The difference in stiffness of double layered reinforced concrete wall based on load-deflection curve 116.2 % to 289.9 % higher than single layered reinforced concrete wall. While based on the experimental results, specimens with double layered rebar in wall is found with higher bending capacity by 56.3 % to 98.9 % compared to single layered of rebar in wall. Experimental data on bending capacity provides important input in the process of structure analysis. Others than that, the outcome obtained from the study can serve as an useful guideline in the design of an efficient joint in wall-slab structural system.

An investigation on effect of rebar on structural behaviour for wall-slab system

Results are given from finite element analysis of 18 strong-axis steel welded beam-column subassemblages with connection reinforcement. For the type of connection configuration considered, Federal Emergency Management Agency (FEMA) recommends connection forces be obtained by locating the plastic hinge at 1/3 depth of beam away from the end of connection reinforcement region. Also, a recent study pointed the location of plastic hinge to be at a distance of depth of beam from the column face. However, the present study shows that the plastic hinge is located at 1/2 depth of beam away from the end of connection reinforcement region. It is observed that connection design forces obtained from the present study are higher as compared to those obtained using the FEMA recommendations. A noniterative procedure for the design of beam-to-column connections using a truss for obtaining connection forces is also presented, which uses this location of the plastic hinge.

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C. V. R. Murty

Papers

Improved truss model for design of welded steel moment-resisting frame connections