Lessons

Lecture 1:  Steel–What is it? Advantages and Disadvantages of Steel, how structural steel shapes are made.

  • What is steel?
  • Advantages and disadvantages of using it as a building material.
  • Advantages: high strength to weight ratio, recyclable, ductile, and tough.
  • Disadvantages: corrosion, melts at high temperatures, fatigue sensitive.
  • Pictures from an actual steel rolling mill are shown and the process for how steel shapes are made is described.
Lecture 2:  Material Properties, Stress-Strain curves, Steel types, Steel shapes
  • Material properties of steel
  • Stress-strain curves of various steel types
  • Structural shapes: wide-flange, tube, pipe, angles, etc.

Lecture 3:  Specifications, Loads, ASD versus LRFD Design

  • Codes for steel design:
    • International Building Code (IBC),
    • AASHTO Bridge Design Specifications,
    • AISC 360 and the 13th Edition of the Steel Manual.
  • Design loads from the ASCE 7 manual
  • Design methods: Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD).
  • “Limit states” of structural failure are defined and described, such as strength and serviceability limit states.
  • Differences between ASD and LRFD
  • Nominal strengths versus allowable strengths
  • Resistance factors (f) versus safety factors (W)
  • Service-level loads versus factored loads.
  • Load combinations and LRFD load combinations reviewed.

Lecture 4:  Load Combinations, Tension Members

  • ASD load combinations example.
  • Tension members limit states:
    • Yielding on the gross cross sectional area
    • Rupture on the net effective area.
    • Example of how to calculate the net area thru a hole, and what hole size to use with a given bolt size.

Lecture 5: Organization of the AISC Manual, Tension members with staggered holes, Effective net areas, Shear Lag Factor, U.

  • Photos of actual engineering projects designed by the author with tension members.
  • Organization of the AISC Manual, how to navigate it, and where to find the Specification in the manual.
  • Spec Chapter D, Tension Members nominal capacity.
  • How to calculate the net area through a tension member with staggered holes,
  • The shear lag factor, U, explained.

Lecture 6: Bolted and welded tension member examples, Connecting elements in tension.

  • LRFD and ASD capacities of two different tension members: one bolted and one welded
  • How to calculate the effective net areas for both including shear lag.
  • Where to find the provisions for connecting elements in tension

Lecture 7:  Connecting element in tension example, Block shear, Block Shear Example

  • Connecting elements in tension
  • Net effective area limitation for connecting elements
  • Connecting element example
  • Block Shear for tension members with an example

Lecture 8:  Design of Tension members, Slenderness ratio for tension members, Threaded Rod tension members

  • Design of tension members
  • How to determine the area required based on a given tensile loading
  • Design steps for tension members
  • Slenderness recommendation for tension members.
  • Example of the design of a tension member
  • Threaded rod tension members

Lecture 9:  Threaded Rod tension members, Compression members–Flexural (Euler) Buckling v. Local Buckling, Effective length (K) factors, Slenderness ratio

  • Threaded rod tension members: nominal strength from AISC Spec
  • 3-hinged arch tension tie problem
  • Compression members (columns)
  • Column limit states:
    • Flexural buckling
    • Local buckling
    • Flexural-torsional buckling
  • Column slendernerss ratio, L/r
  • Effective Length factor, K

Lecture 10:  Effective length factors for braced and unbraced frames, Euler Buckling column capacity

  • K factors for sidesway frames (moment frames) and for braced frames (non-sway frames)
  • Approximate K values for typical columns
  • Column strength dependence on effective slenderness
  • Graph for short, intermediate, and long columns.
  • Short and Intermediate columns fail by a combo of yielding and buckling (called inelastic buckling)
  • Long columns fail by elastic buckling, also called Euler Buckling.
  • AISC equations for the critical column stress, Fcr,
  • Example problem: capacity of a wide-flange column three different ways:
    • AISC equations (fast)
    • AISC Table 4-22 (faster)
    • AISC Table 4-1 (fastest)

Lecture 11:  Determining which buckling axis controls column capacity, local buckling; Compact, Noncompact and Slender sections (Local Buckling)

  • How column strength depends on which direction a column buckles:
    • Strong (x-x) axis or weak (y-y) axis buckling
    • Depends on the direction with the longer effective slenderness ratio.
  • Column strength example with slenderness ratio in the strong direction (KLx) controls.
  • How to convert KLx to an equivalent KLy in order to use AISC Table 4-1
  • How to do the problem using Table 4-22.
  • Local buckling of compression members
  • Stiffened and unstiffened elements of a section
  • Width-thickness ratio, b/t
  • Compact, noncompact and slender sections

Lecture 12:  Local Buckling, column capacity example, Torsional buckling

  • Local buckling (LB) part 2
  • Review of compact, noncompact or slender categories
  • b/t limits shown in AISC Table B4.1
  • We show how AISC Table 4-1 flags whether a section is noncompact and already accounts for LB in its compression strength capacities
  • Column example showing how to find out if it’s slender
  • What is torsional buckling in columns and how does it occur?

Lecture 13:  Compression Member examples

  • A number of compression member examples are worked, showing you how to quickly determine column sizes using the Tables in Part 4 of the AISC Manual.
  • Built-up columns also briefly discussed

Lecture 14:  Single angles in compression, Columns in frames, K factors in sidesway frames

  • Single angles compression members
  • Examples and photos of columns in steel building frames
  • How effective length (K) factors can be estimated for columns in frames using a commonly-used nomograph.

Lecture 15:  K factors in sidesway frames, column baseplates

  • Continued discussion on how K factors can be estimated for columns in frames
  • Example showing how to use the nomograph chart to find K.
  • Another example of sizing a wide-flange column in a frame using a K value determined from the nomograph
  • Design column base plates—Part 1

Lecture 16:  Column baseplate design and example

  • Design of column base plates—Part 2
  • Column base plate design example for  wide-flange column

Lecture 17:  Intro to Beams, Elastic and Plastic Section Modulus, Bending stresses

  • Design of steel beams, one of the most important topics in steel design.
  • What is a beam?
  • Basic concepts of bending stresses in a beam
  • What is the yield moment in a beam?
  • What is the plastic moment and what is a “plastic hinge” in a beam?
  • How to find bending stresses using the flexure formula
  • Simple example of beam bending stresses
  • What is the plastic section modulus, Z, and do you find it? (Note: There is a small error at the end of the video in how Z is calculated which is corrected in Lecture 18.

Lecture 18:  Design of Beams, Lateral Torsional Buckling (LTB), Unbraced Length, Bending Capacities: Plastic (Zone 1), Inelastic LTB (Zone 2), Elastic LTB (Zone 3)

  • Review bending stresses in beams
  • Review how Z is calculated, correcting the small error from Lecture 17.
  • What is Lateral Torsional Buckling (LTB) in beams?
  • How LTB be prevented by bracing the compression side of a beam.
  • Bending strength of a beam and strength based on its unbraced length, Lb.
  • Methods of laterally bracing a beam: by metal deck, other beams or joists.
  • Photo of metal decking on steel beams from an actual steel building project.
  • Bending strength (moment capacity) of a beam gets smaller as the unbraced length, Lb, increases.
  • 3 zones of bending strength of a beam versus its unbraced length:
    • Plastic (Zone 1)
    • Inelastic LTB (Zone 2)
    • Elastic LTB (Zone 3)
  • Design of beams in Zone 1: fully plastic capacity
  • Example of beam in Zone 1

Lecture 19:  Design of Beams in Zone 1, 2, and 3

  • 2 beam design examples with its unbraced length equal to zero
  • Review beam moment capacity in Zones 1, 2, and 3 (Plastic, Inelastic Lateral Torsional Buckling, and Elastic LTB)
  • What is the lateral torsional buckling modification factor, Cb
  • What is the Bending Factor in AISC Table 3-2
  • Beam design example with its unbraced  length of 8′-0″

Lecture 20:  Design of Beams using AISC Table 3-10, Local Buckling of beams

  • Video showing lateral torsional buckling in 3D
  • Design of beams in Zone 3, elastic lateral torsional buckling
  • AISC Table 3-10, moment capacity of W shaped beams for any unbraced length
  • Beam design example using AISC Table 3-10 and unbraced length of 20′-0″
  • Local buckling of beams using AISC Table B4.1 for width-thickness ratios

Lecture 21:  Shear and Deflection of Beams

  • When is shear critical in steel beams?
  • Shear stresses in beams
  • Shear capacity using the AISC provisions of Specification Chapter G
  • What is the web shear coefficient, Cv?
  • Beam shear example
  • Beam deflections–when are they critical?
  • Beam deflection example showing how to find lightest section based on moment of inertia using AISC Table 3-3

Lecture 22:  Shear and Deflection of Beams, Beams with concentrated forces, Beam bearing plates

  • Beam deflections using a simplified AISC equation
  • Webs and flanges of beams with concentrated loads: web crippling, web yielding, local flange bending
  • AISC Chapter J.10 provisions for beams with concentrated forces
  • Beam bearing plates and a bearing plate example

Lecture 23:  Biaxial Bending of beams, Shear Center, Combined bending and axial force (beam-columns), drag struts

  • Examples of biaxial bending of beams: crane runway beams, roof purlins, AISC equations for biaxial bending
  • Shear Center: torsion on open and closed sections
  • AISC User Note F1.1: Selection Table for the Application of Chapter F Sections
  • Examples of beam columns: rigid frames, most building columns, drag struts, explanation of a drag strut

Lecture 24:  Beam-columns, second-order (P-Delta) effects, Amplified First-Order Elastic Analysis, Cm factors

  • Beam-column example: top chord of a truss
  • AISC Chapter H equations for beam columns
  • Second order effects (P-Delta) effects based on AISC Chapter C, Stability Analysis and Design
  • The difference between member p-d effects and frame drift P-D effects
  • First-order analysis versus second-order analysis
  • Amplified first-order analysis to approximate second-order effects
  • Magnification (amplification) factors B1 for p-d effects and B2 for P-D effects
  • How to calculate Cm for use in B1 equation
  • Example problem: check a tube column with axial load and moment

Lecture 25:  Beam-column examples:  HSS Tube column and WF column with bending

  • Example problem: finish checking the tube from last lecture as a beam-column
  • Example problem: WF beam-column design
  • Exam #2 discussion

Lecture 26:  High-strength Bolted connections, Types of Bolts, Tightness of Bolts, Bolt shear failure modes and shear strength

  • Why use bolted connections; advantages of bolted connections
  • What are rivets and why did bolts replace them
  • Types of bolts: A307, A325, A490
  • Bolt tightness: Snug Tight (ST), Pretensioned (PT), Slip-Critical (SC) and what are they and when do you specify them
  • Methods to tighten bolts to PT or SC tightness: Turn of the Nut, Calibrated Wrench, Direct Tension Indicator, Twist-off or Tension-Controlled Bolts
  • Examples of Bolts in Shear and Tension
  • Bolts in single shear and double shear
  • Shear failure modes:  bolt shear, rupture on net section, bearing failure of plate, shear tearout
  • Bolts in combination with welds: need SC bolts
  • Bolt hole sizes: Standard, oversize, short-slotted, long-slotted
  • Minimum spacing and edge distances for bolt holes
  • Nominal shear strength of bolts
  • Bolt Threads excluded (Type X) versus included (Type N) in the shear plane

Lecture 27:  Shear strength of bolts, Bearing strength of bolts, bolt shear example, Pretensioned (PT) and Slip-critical (SC) bolts, SC bolt example

  • Shear strength of bolts: limit states of bolt shear and plate bearing from AISC Spec section J3
  • Bolt shear example problem with 7/8” A325-X bolts using AISC tables to find bolt shear strength
  • When are pretensioned or slip-critical bolts used?
  • Nominal strength of SC bolts
  • SC bolt example using AISC tables to find bolt slip-critical strength

Lecture 28:  Bolts in tension, combined shear and tension in bolts, eccentric shear on bolts (intro), Welds, Advantages/Disadvantages, Types of Welds

  • Example of bolts in tension
  • What is prying action on bolts and how do you avoid it?
  • Tension capacity of bolts based on AISC Equation J3-1
  • Photo of a moment frame connection with pretensioned bolts
  • Bolts in combined shear and tension capacity
  • When can you ignore combining shear and tension?
  • Eccentric shear on a bolt groups
  • 3 methods for eccentric shear: Elastic, Effective Eccentricity, and Instantaneous Center of Rotation Methods
  • Welding—What is it?
  • Advantages and disadvantages of welded joints
  • Types of welding: stick versus wire feed welding; SMAW, SAW, FCAW, GMAW processes
  • Exam #2 Q&A

Lecture 29:  Weld Inspection methods, Complete Joint Penetration welds, Partial Joint Penetration, fillet welds, plug and slot welds, Weld Symbols

  • Weld Inspection methods: visual, dye penetrant, magnetic particle, ultrasonic, radiographic
  • Types of welded joints: fillet welds, groove welds, plug welds
  • Complete joint penetration welds versus partial joint penetration groove welds
  • Weld Symbols, examples of welded joint symbols

Lecture 30:  Strength of Fillet and groove welds, Fillet weld requirements

  • Effective throat and leg size of fillet welds
  • Strength of a fillet welds and groove welds
  • Base metal versus weld metal strength
  • Weld metal tensile strength, Fu
  • Weld electrodes, E70XX, E60XX, etc
  • Example of how to calculate strength of 1” long fillet weld
  • Fillet weld limitations: minimum length and leg size
  • Reduction in strength for long welds
  • Maximum fillet weld size

Lecture 31:  Base metal versus fillet weld strength, fillet weld capacity per inch of weld, fillet weld examples, combined bending and shear on weld treated as a line

  • How to tell if base metal or weld metal controls fillet weld strength
  • How to quickly calculate the strength of fillet welds per inch of length
  • Fillet weld examples
  • Fillet weld strength perpendicular verus parallel to the weld axis
  • Combined bending and shear on a weld group
  • Section properties of weld groups treated as a line

Lecture 32:  Beam connections, Simple Shear Connections, Moment Connections, Design of Single-Plate Shear tab connections

  • Partially Restrained (PR) versus Fully Restrained (FR) connections
  • Single Plate Shear Tab connection
  • Double Angle shear connection
  • Prequalified bolted moment connection—picture and detail
  • Prequalified welded moment connection—detail of Reduced Beam Section (RBS) connection
  • Design of single plate shear tabs and example problem

Lecture 33:  Final Exam review, Intro to Composite Beams, Intro to Steel Joists and Joist Girders, Intro to Seismic Braced Frames

  • Final exam review
  • How to check bolt bearing on the beam web for a single plate shear tab
  • What are composite beams? How are composite beam systems erected?
  • Picture of composite beam stud welding
  • Before and after pictures of complete joint penetration column splice welds showing weld runoff tabs
  • Pictures of single plate shear tab connections
  • What are steel joists and joist girders?
  • Picture and details of typical joists and joist girders
  • How are joists and joist girders specified?
  • Examples of steel braced frames: Ordinary Concentrically Braced Frame (OCBF), Special Concentric Braced Frame (SCBF), Buckling Restrained Braced Frame (BRBF)
  • Pictures of BRBF and SCBF for comparison

Bonus PowerPoint Video:  Real World Steel Design Projects–Case Studies

Advanced Lectures: Composite Beam design

Class 1: Intro to design of Composite Beams

  • What are composite beams?
  • Drawings and pictures of composite beam systems
  • Camber in composite beams
  • Erection sequences for unshored versus shored composite beam systems
  • Advantages and disadvantages of composite beam systems

Class 2: Design of Composite Beams

  • How to find the effective slab width
  • How does horizontal shear transfer happen in a composite beam?
  • How to find the number of required weld studs to transfer the horizontal shear force
  • Stud requirements for composite beams with metal deck
  • How to find the nominal moment strength of composite beams using AISC Table 3-19.

Class 3: Composite Beam Design Example

  • Step-by-step example problem of a composite beam design using metal deck and lightweight concrete.
  • Beam is sized, camber and number of required studs are determined
  • Partial composite action is explained

Advanced PowerPoint lecture: Second-order effects in steel structure