NTNU

Norwegian University of Science and Technology

TKT 4198

Structural Design – Advanced Course

Problem Set 2

Delivery Deadline: Sunday 18/10/2015

Problem set 1 goal was the solution of a structure with elastic restrains and the design of joints

with the only requirement of their ULS capacity. This second problem is focused on the stiffness of

joints.

1 Stiffness of the joint With the joint shown in “Problem Set 1 – Example of Solution.pdf”:

a) Classify the joint according to strength (full-strength or partial strength joint) b) Classify the joint according to stiffness (rigid, semi-rigid or nominally pinned). Here, assume

kb=25, length of the column Lc=3m.

c) Check that the initial stiffness of the joint is larger than or equal to mink (the minimum

stiffness of the joint that guarantees the SLS mid-span displacement to be within the limit, see problem 1). As a simplification, assume the column flexural stiffness equal to . This

means that the rotation at the beam ends is due to the rotation of the joint only ( 0 ),

see figure below.

d) Re-calculate the MEd in A with the obtained initial stiffness. e) Stiffen the joint so to increase the initial stiffness of at least 10% but remain in the “semi-

rigid domain” f) Stiffen the joint so that it is classified as “rigid joint”. Try to stiffen the as little as possible

so to obtain a “cheap” rigid-joint (i.e. do not put stiffeners everywhere). g) Make a plot like in Figure 5.4 of EC3-1-8 reporting the classification limits and the different

curves with stiffness from points c, e and f. Report also the resisting moments and the external moments.

2 Additional data: Standards:

Eurocode 0 and Eurocode 3 shall be used. For nationally determined parameters use the

Norwegian National Annex.

3 Hints Make use of excel or software like Mathcad or SMath Studio since the design of these

types of joints is done in an “iterative way”. Hand calculations may require longer time since new calculations shall be performed each time a modification is performed. Moreover, this problem will be continued in Problem set 2.

Use notation as in Eurocodes 0 and 3 strictly. This gives advantages in applying Eurocodes’ formulas, avoids strange names for variables and is a good habit to learn for easier the reading of your calculations by other people.

Write references of all main formula used (references to book and/or standards);