Chapter 5 – Understanding, Misunderstanding
Table of Contents
5.1 Recognizing the Never-Ending Challenge
5.2 Crane Runway Girders Are Not Bridge Girders
5.3 A Humble Restart Once More
5.4 Looking Into the Environment Where CRG Is Living In
5.5 Structural Boundary Conditions – As Understood
5.6 Structural Boundary Conditions – As Understood Once More
5.7 Structural Boundary Conditions – As Idealized
5.8 Structural Boundary Conditions – As Anticipated
5.9 Structural Boundary Conditions – Unconditionally Detailed
5.10 Structural Boundary Conditions – Bad Examples
5.11 Structural Boundary Conditions – Lessons Learned
5.12 Finite Element Analysis – Users Beware
5.13 Finite Element Analysis – Tool of Approximation
5.14 Finite Element Analysis – I/O Flaws
5.15 Finite Element Analysis – Latent Difficulties
5.16 Finite Element Analysis – Garbage-In-Garbage-Out
5.17 Stiffness – As Understood
5.18 Lateral Stiffness – Standalone Crane Runway Girder
5.19 Lateral Stiffness – Coupling Crane Runway Girders
John Fong (馮永康) . Bill Vanni
Structural Design Corporation
1133 Claridge Dr., Libertyville, IL 60048
©July 2018 – Oct 2019, 2022, 2024
By natural instinct ‒ or for obvious reasons ‒ many Structural Engineers would stay away as much as they can from being assigned to deal with Open Sectioned Crane Runway Girders with Unsymmetrical Section or in other words that of Arbitrary Profile Geometry (CRG).
Consider the feeling of an individual who comes across the subject of unsymmetrical sectioned girders as much as been expounded upon in this Series:
To a great extent to those Lighthearted Structural Engineers who maintain an arm’s length from the core of the matter; while on their leisure pursuit, it takes minuscule aspiration for them to shun off the opinions appeared in the preceding Chapters
But then when coming down to doing the real thing by the real rules in the real time, they sure need to contend with “a little bit” of challenge prior to even laying the groundwork for good measure, of which such as locating the shear center for unsymmetrical sections and calculating the whole slew of associated must-have section properties ‒ and that alone is well qualified as a special topic all by itself
Understandably, to many “pioneers” who had already “gained” indelible experience in tackling comparable challenges, the subject matter must be exceedingly profound to them. It is no surprise that they would prefer to avoiding all CRG troubles all together at all cost.
But even at all avoidance we cannot avert facing the reality in the real world; because unsymmetrical sectioned structures are not going away any time soon. This applies not only to CRG applications but could also apply to other unavoidable non-CRG situations.
In spite of rendering our absolute best efforts to resolve every engineering-design issue and to overcome every CRG–themed challenge that comes our way, it is not prudent to leave open issues unresolved for all time. Whether we take on those issues willingly or not, the reality is, sooner or later someone is going to need to address the need for unsymmetrical sectioned structures.