Questions and discussion for this lecture live here. Fire away by hitting Reply below 
At 25:30, shouldn’t K = 4EI/L since the adjacent support is a fixed support?
Hey @lekaisakaio,
The simplest way to look at this is as follows:
- if we have rotational resistance provided at both ends of the beam segment, either by a fixed support, or continuity over the support (the first three examples in the summary), the stiffness is 4EI/L.
- If we only have rotational fixity provided at one end, then the beam segment stiffness is reduced to 3EI/L.
Keep this in mind and you won’t go wrong.
Seán
Hi @Sean, would you please provide some real world structured examples to achieve these connection? I like to have a clear picture in my mind how to achieve these connections or to identify these connections if I see a structure. Thanks
Hi @uv.chaudhary27, real-world structural steel connections are typically classified as ‘moment’ and ‘simple’ connections. Any steel design reference text will outline the key features associated with each connection.
But in summary, simple connections, i.e. those that are designed to facilitate a degree of rotational flexibility, are often formed using fin-plates to connect the web of the steel beam to an adjoining column, for example. A feature of these connections in the positioning of bolts, closer to the neutral axis of the beam, reducing the moment resisting capacity of the joint.
Moment connections on the other hand usually have bolts spread through the depth of the connection and in many cases will include a haunch to increase the lever arm available for bolts.
In reinforced concrete, it is difficult to make the case that any connection is not a full moment connection, given the monolithic nature of the form. There is some nuance here when it comes to reinforcement detailing at the connection, but generally we will consider all connections to be moment connections in an RC frame.
Hope that helps.
Seán