Steel Structures

What does it mean if a steel is of S355 grade?

It’s yield strength is 355 N/mm².

True/False

Non-Linear material characteristics affect lateral torsional stability of beams.

BUT are not taken into account in the elastic lateral torsional buckling theory.

True

True/False

Geometric imperfections affect lateral torsional stability of beams

BUT are not taken into account in the elastic lateral torsional buckling theory.

True

True/False

Eccentricities of loading affect lateral torsional stability of beams

BUT are not taken into account in the elastic lateral torsional buckling theory.

True

True/False

Residual stresses in the member from manufacturing affect lateral torsional stability of beams

BUT are not taken into account in the elastic lateral torsional buckling theory.

True

What is the imposed load factor (gamma_Q) ?

1.5

What is the dead load factor (gamma_G) ?

1.35

What is a primary beam?

A beam that spans between columns, transfers the load from the secondary beam and slab onto the columns

What is a secondary beam?

A beam that spans between primary beams

True/False

At a pinned connection, the bending moment is always zero.

True

What axis is the vertical axis (weak axis)?

z-axis

What axis is the major axis (axis that is hard to bend about)?

y-axis

What does this term represent, and what is its value (generally)?

The load factor for buckling (= 1).

What does the term ‘W’ represent?

The plastic modulus.

True/False

This sign convention is followed by Eurocode.

True

True/False

If this value is less than 0.4, Lateral Torsional Buckling effects must be considered.

False, if it is less than 0.4, Lateral Torsional Buckling effects can be ignored.

When can this simplification be made?

When you are calculating lateral torsional buckling slenderness of I-sections or H-sections.

When determining the significance of second-order effects, what term needs to be considered (for loads)?

EHF, The Equivalent Horizontal Force

How is the EHF (Equivalent Horizontal Force) calculated?

It is 0.5% of any vertical loads imposed at each braced frame.

EHF (Load Type) = 0.005 x N_ED

What is the value of, E, the Young’s Modulus of Steel?

210 GPa = 210,000 MPa = 210,000 N/mm²

What condition must this value satisfy, to neglect 2^nd order effects?

> 10

What does an outrigger do?

An outrigger, connects the peripheral columns to the core columns and helps improve lateral stability (alt. to bracing)

What is one of the ways outriggers improve the lateral stability of a structure?

It improves stability by reducing the slenderness.

Which of the following is true for how an outrigger improves the lateral stability of a structure?

It reduces moments and deflections, compared to a free-standing case (i.e. no outrigger).

What is the formula for N_c,f,total?

What is implied if N_a,pl > N_c,f,total ?

The plastic neutral axis (PNA) is within the steel (x_c > h_t).

Which number in C35/45 represents the cylinder strength of the concrete?

35

When given two strengths of concrete (cube, cylinder), which do you take?

Cylinder