Although as a qualified structural engineer, you'll be well-versed in designing every member of a building, but you can still be left scratching your head when confronted by unexpected failures in steel connections.  Such incidents can lead to major client dissatisfaction and potentially to damaging insurance claims against your company.

With this in mind, here's a helpful summary of the most common causes of failures in steel structure connections to help you to avoid such problems in the future.

Connection failures

Failures in connections are one of the most frequent and critical failures in buildings that incorporate steel skeletal structures.

When designing steel members, it's essential to consider the design of the joint in relation to the maximum load envelope that will be placed around it by the building it supports.  It goes without saying that the joint must be designed and fabricated in order to withstand maximum possible force, but you must bear in mind that it is usually unpredicted force that causes a joint to fail.  This is because, unlike solid steel, which is uniform and cast as a single piece, a joint is more brittle.

In order to accommodate this, you must consider the potential for failure in connections when calculating structural values.  Even if the connection that you have designed should carry the compressive or tensile loads as per your calculations, it's always wise to use additional bolts or welds.  This not only takes into account possible errors in your calculations, it also factors in an element of risk associated with the bolts or welds themselves.  If you only fit one bolt or weld to a joint and that bolt or weld is faulty, the joint will fail under a load that should ordinarily be easily accommodated.  It therefore makes sense to fit two or even three bolts or welds, rather than just one.

When considering welds, you should always be conservative in determining the weld length, as this is usually carried out on-site.  It's therefore good practice to discuss weld length in greater detail with the construction engineers on-site, presenting the argument outlined above.

In conclusion

When designing buildings incorporating steel members in their structural, it's important to consider the design of joints and connections in relation to the predicted and unpredicted load they could reasonably be expected to bear.  Remember to account for faulty materials and welds and be prepared to discuss your design further with the engineers on-site.   For more information, contact companies like Jeffrey Hills and Associates.