M.M. Hrabok ● 2007M.U. Hosain ● 2007

Structural Steel DesignM.M. Hrabok, Ph.D., P.Eng.

(Saskatoon, SK)M.M. Safar, Ph.D., P.Eng.

(Calgary, AB)

(September 2012)

“Design of Steel Structures”according to CAN/CSA-S16-09

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CE470 (September 2012) i

PrefaceCourse DescriptionCE 470 is an introduction to the structural design of members and connections forsteel structures in accordance with the National Building Code of Canada 2010(NBCC-2010) and the Canadian “Limit States Design of Steel Structures” StandardCAN/CSA-S16-09 (10th Edition).

Members and components in CE470 include tension members, beams, columns andbeam-columns, as well as bolted and welded connections. Emphasis is placed ondesign, fabrication and understanding the rationale and basis of CSA-S16 Standards.Framed structures are designed for second-order elastic (P-P-) forces and notionallateral loads. Factored load combinations are determined from “principal andcompanion design loads” according to NBCC-2010.This class is only for students who have an aptitude for structural design and strive tobecome structural design engineers. It is the art of: (i) using materials that haveproperties which can only be estimated, (ii) to build real structures that can only beanalysed approximately, (iii) to withstand forces that are not accurately known, so thatthe public is professionally, confidently and responsibly assured of SAFETY!The present set of notes originated from Professor M.U. Hosain’s class notes (2005)with subsequent updates, revisions and additions by M.M. Hrabok and M.M. Safar.

Prerequisites: CE 321 “Structural Systems and Materials” and its prerequisites.Optional: CE 463 “Advanced Structural Analysis”.

CE 470 (Sept 2012) Lecture Outline:

Chapter Topics± No. ofLectures(1½ hr/ Lecture)

1. Introduction: objectives of design and analyses; design methods, philosophies,

factors-of-safety; handbooks, codes, standards and specifications;steel shapes and properties; format and contents of S16-09 andCISC Handbook (10th Edition - 2010).

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2. Tension Members: design of tension members based on:o yield on gross area,o fracture on net area (Cochrane’s formula),o reduction of net area for shear lag,o yielding and fracture mechanisms for “tension & shear” blocks.

example problems.

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CE470 (September 2012) ii

Chapter Topics± No. ofLectures(1½ hr/ Lecture)

3. Bolted Connections: types of mechanical fasteners and properties. connection behaviour and design of bolts in shear for:o bearing connections,o slip-critical connections (“friction connections”).

“shear lag” considerations for bolted connections. design of bolts in tension, and calculation of prying forces. interaction equations for bolts in combined shear and tension. instantaneous centre-of-rotation (ICR) methods and traditional

conventional methods of calculating bolt forces for eccentrically-loaded bolted connections with:o eccentricity in-the-plane of the faying surfaces,o eccentricity normal-to-the-plane of the faying surfaces.

example problems.

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4. Welded Connections: welding fundamentals, terminology, geometry, weld symbols,

electrodes, and metallurgical properties of welded connections. behaviour and design capacity of welds commonly used in

structural steel fabrication:o welding processes, groove and fillet welds, parent material and

electrode properties, “effective throat”, “fusion face”, and “heat-affected zone” concepts,

o capacity of welds with respect to weld orientation and directionof loading.

“shear lag” in welded connections of tension members. instantaneous centre-of-rotation methods (ICR) and conventional

methods of calculating resultant forces for eccentrically-loadedwelded connections with:o eccentricity in-the-plane of the faying surfaces,o eccentricity normal-to-the-plane of the faying surfaces.

design of connections to prevent brittle fracture (Annex L). example problems.

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CE470 (September 2012) iii

Chapter Topics± No. ofLectures(1½ hr/ Lecture)

5. Columns: review of stability concepts of bifurcation and elastic buckling of

bars (columns), plates and shells. elastic buckling of plates in the context of “local buckling” of

elements of wide-flange shapes. design of columns to avoid local buckling. the role of classical Euler’s elastic buckling equation for overall

member buckling and its application and limitations in S16. design of symmetric and asymmetric members in compression. column “effective length” concepts and slenderness ratios. elastic and inelastic behaviour and axial load capacity of columns

using Loov’s double-exponential curves from S16. design of simple columns using CISC Handbook equations,

design aids, tables and charts. design of columns in real structures with due regard for:o braced or non-sway structures versus unbraced or sway

structures.o “2nd-order analysis” concepts for framed structures,o computer modeling of steel structures and connections.

provisions for single-angle members in compression. example problems.

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6. Beams: local buckling of compression elements in flexural members. torsion mechanisms in thin-walled open sections;

(i) St.Venant torsion (pure or uniform torsion), and(ii) restrained-warp torsion (non-uniform or “warping” torsion)

and warping constants. shear centres for flexure and centres-of-rotation for torsion. classical critical buckling moment Mu equation for elastic lateral-

torsional buckling (LTB) of thin-walled open-section beams ofdoubly-symmetric cross-sections and loaded by uniform moment.

introduction to the textbook “Guide to Stability Design Criteriafor Metal Structures” by R.D.Ziemian 6th Edition (2010).

calculation of Lu (spacing of compression flange brace points)such that LTB of compression flange does not govern capacity.

calculation of span Le bracing of compression flange where“inelastic lateral-buckling” meets the “elastic buckling” curve.

conversion of non-uniform moment diagrams to uniform.

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CE470 (September 2012) iv

Chapter Topics± No. ofLectures(1½ hr/ Lecture)

design of beams using Handbook design aids, tables and charts. introduction to lateral bracing concepts and systems. example problems.

7. Beam-Columns: design of members subjected to combined axial compression and

biaxial bending according to S16 for “strength and stability”criteria using interaction equations for the following cases:

o cross-sectional strength of member and connections,o overall in-plane strength of member,o “lateral torsional buckling” strength of member,o biaxial bending strength of member without axial loads.

examples problems for both types of framed structures:o non-sway structures (braced or sidesway prevented), ando sway structures (unbraced or sidesway permitted).

for all problems, design forces are from P- and P- analyses. 2nd-order analysis --- brief review and use of commercial programs

with particular emphasis on SAP2000. example problems.

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8. Seismic Design Requirements (Clause 27): review of fundamental concepts of seismic design. Seismic loading according to NBCC-2010 “ESFP method”. overview of Clause 27 example problem.

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9. Composite Beams and Floors (Clause 17): design of steel floor beams with composite concrete slabs. example problems.

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10. Cyclic Loading and Fatigue (Clause 26): live-load induced fatigue and distortion-induced fatigue. 1½

11. Vibration Analysis and Modeling of Floors - itp

Total No. of Lectures (hours) ≈ 25 (38 hrs)

CE470 (September 2012) v

teaching material: → CE 470 Class Notes, handouts and CISC Handbook.

CISC Handbook of Steel Construction10th Edition (CSA-S16-09),

http://www.cisc-icca.ca/content/publications/publications.aspx

optional: - Limit States Design inStructural Steel (2010) Kulak and Grondin.

Evaluation Procedure:Lab. Assignments 10 %Midterm Examination 30 %Final Examination 60 %

A student must pass at least one of the exams (midterm or final) in order to receivecredit for the course.Homework problems will be assigned bi-weekly. “Lab sessions” are formallyscheduled for every second week; lab attendance is not mandatory but assignmentsmust be handed-in on time. Additional assistance (if required) on assignments,lectures and course content will be made available upon request.Participating in site trips and other out-of-classroom activities is at the student’soption and discretion.Other instructors (including licensed practicing engineers or E-I-Ts) may presentsome of the lectures.More information is posted on the CE470 website:

http://www.engr.usask.ca/classes/CE/470/prepared by: M.M. Hrabok

(September 2012)