(SEM VII) THEORY EXAMINATION 2019-20 DESIGN OF STRUCTURES-IШ

SECTION A – Explanation

Section A of the Design of Structures-III paper is designed to test the student’s basic theoretical knowledge and familiarity with IS 800:2007 provisions related to steel structures. All questions in this section are compulsory and are to be answered briefly. The examiner checks whether the student understands fundamental terms, code limits, and basic design concepts that are repeatedly used in steel design problems.

The questions include determination of minimum pitch and edge distance for M20, grade 4.6 bolts, listing IS clauses for minimum and maximum weld size, utility of splices in tension members, formulas used to calculate different strength criteria of tension members, modes of failure of compression members, utility of gantry girders, and definition of prying forces. These questions cover bolted connections, welded joints, tension members, compression members, and industrial steel structures.

For example, the question on pitch and edge distance checks whether the student remembers codal spacing limits to avoid tearing and ensure proper force transfer. The weld size question checks understanding of practical welding limitations. Questions on tension and compression members test knowledge of yielding, rupture, buckling, and instability. The gantry girder question connects steel design with industrial applications such as crane loads. Prying force checks understanding of additional tensile forces induced in bolts due to deformation of connected plates. Answers in this section must be concise, technically correct, and aligned with IS 800:2007 terminology. Excessive explanation is not required, but clarity and accuracy are essential.

SECTION B – Explanation

Section B evaluates the student’s conceptual understanding and ability to explain steel behavior and connection design in moderate detail. Students are required to attempt any three questions, each carrying equal marks. This section mainly focuses on stress–strain behavior and design strength calculations of welded and bolted connections.

The questions in this section include explanation of the stress–strain curve of mild steel with a labeled diagram, calculation of design strength of a welded joint in a truss girder using fillet welds, and explanation of block shear failure in tension members with diagram and formulas. These questions test understanding of material behavior as well as application of IS 800 design equations.

For instance, the stress–strain curve question checks understanding of elastic limit, yield plateau, strain hardening, ultimate stress, and fracture, which is essential for limit state design. The welded joint numerical problem tests the ability to calculate weld strength based on throat area, weld length, and safety factors, and also checks understanding of how joint strength increases when welding is done on all sides. The block shear question evaluates understanding of combined shear and tension failure in bolted or welded connections, which is a common failure mode in tension members. Answers in Section B should be written in a logical sequence, supported by neat sketches and formulas where required, and usually extend to about one and a half to two pages per question.

SECTION C – Explanation

Section C is the most important and highest-weight section of the Design of Structures-III paper. This section tests the student’s in-depth understanding, analytical ability, and practical design skills. Students must attempt one part from each question, as internal choices are provided.

The questions in Section C include comparison between Working Stress Method and Limit State Method of steel design, determination of maximum load resisted by a welded bracket connection, design of a tension member and its connection lug angle for a given axial load, and computation of tensile strength of an angle section considering gross section yielding and net section rupture. These questions require detailed explanations, numerical calculations, and proper application of IS 800:2007 clauses.

For example, the comparison between WSM and LSM tests theoretical understanding of design philosophies, safety factors, and serviceability considerations. The bracket welding problem tests calculation of resultant forces and weld strength under eccentric loading. The tension member design problem checks ability to select suitable steel sections, check all limit states, and design proper connections. The angle section strength problem tests understanding of gross area yielding and net area rupture, including bolt hole deductions. Answers in this section must be systematic, well structured, and supported by calculations, diagrams, and codal references. Each answer generally extends over two to three pages and significantly influences the final score.

Overall Understanding of the Paper Pattern

The Design of Structures-III (RCE-701) question paper is structured to test students progressively from basic theoretical knowledge to advanced design application. Section A focuses on definitions, codal limits, and basic concepts, Section B evaluates material behavior and connection strength calculations, and Section C tests complete design and analytical skills required for real-life steel structures. A student who understands this structure can prepare effectively by revising IS 800 clauses for Section A, practicing standard problems for Section B, and mastering full design procedures for Section C.

A strong preparation strategy includes regular practice of tension and compression member design, welded and bolted connection problems, and clear understanding of limit state design philosophy. Section C carries the maximum weight and should be given special attention to score high marks.