Rahul Leslie

Kerala Public Works Department · Buildings Design DRIQ

On 26th April, 2023, the BIS released the 7th draft of the codes for seismic analysis of structures, namely, IS 1893:2023 (WC) Part 1&2, for wide circulation. The final form of the to-be released revision of the IS 1893 codes are expected to be more of less the same as the IS 1893:2023 (WC) codes, except that some values or some specifications may...

The loss of sign in the output results of Response Spectrum Method has been a subject of discussion in literature, highlighting the issues caused, manifesting primarily in: (i) the loss of relative signs of forces acting on the structural members and (ii) the loss of relative signs of the support reactions. The method of Dominant Mode Signage (DMS)...

FEM took birth from a technical paper titled “Stiffness and Deflection Analysis of Complex Structures”, published in 1958, authored by Turner, Clough, Martin and Topp. It was the kick start of a revolution that forever changed the way we approached the analysis of structures –- be it buildings, bridges, vehicles, aircrafts or rockets. It was by 196...

In the response spectrum analysis, the method prescribed for seismic analysis of multi-storied buildings in IS 1893(part-1)2002, like other similar codes, is the method of combining the modal responses, followed by combining them by the SRSS or CQC to obtain the final response forces for design. This method is referred to, by the authors, as the In...

To those familiar with the Indian seismic code of IS:1893-2002, Dynamic analysis is mostly Response Spectrum Analysis (RSA); and to those familiar with the research and academic field, Non-linear Dynamic analysis is Non-linear Time History Analysis (THA). And the THA is not the nonlinear counterpart of RSA. This was where the core of the confusion...

The performance of a structural system under seismic action can be evaluated by resorting to non-linear static analysis. This involves the estimation of the structural strength and available capacities and the comparison with the deformation demands at desired performance levels. Seismic evaluation of existing structures and of the proposed design...

Non-linear Static analysis or Pushover analysis is a very practical method fit for day to day use in the structural design field, when compared to Non-linear Time History analysis due to its computational intensity and experienced judgement required. However it is found that Non-linear Time History analysis is more accurate than Pushover analysis,...

Indian standard codes (IS 456:2000, IS 13920: 1993) have not given particular attention for the design of setback buildings. This paper addresses the effect of irregularities in elevation on the seismic performance of reinforced concrete (RC) framed buildings with infill brick walls. The seismic parameters such as fundamental time period, inter sto...

Pushover analysis has been in the academic-research arena for quite long. The papers published in this field usually deals mostly with proposed improvements to the approach, expecting the reader to know the basics of the topic... while the common structural design practitioner, not knowing the basics, is left out from participating in those discuss...

One of the emerging fields in seismic design of structures is the Performance Based Design. The subject is still in the realm of research and academics, and is only slowly emerging out into the practitioner’s arena. Seismic design is slowly transforming from a stage where a linear elastic analysis for a structure was sufficient for both its elastic...

Pushover analysis is a static, nonlinear procedure in which the magnitude of the structural loading is incrementally increased in accordance with a certain predefined pattern. With the increase in the magnitude of the loading, weak links and failure modes of the structure are found. Static pushover analysis is an attempt by the structural engineeri...

Structural health monitoring of bridges involves measurement of dynamic properties to assess its structural integrity. At the time of an anticipated damage, it is essential to detect and locate damage, if any. Characterisation of modal parameters, namely, natural frequencies and mode shapes, is the most promising route to detection of damage, which...