Structural Engineering

A waffle slab is made of a thin topping supported by ribs running in both directions, giving it the appearance of waffle when looked from below. Waffle slabs are a special type of reinforced concrete slab, where aesthetics meet with certain structural characteristics. They have advantages such as the aesthetics, higher load capacity and longer spans. Since they are stiff due to their higher overall thickness, they reduce floor vibrations, which is also desirable in hospitals, labs. Their rigidity also enable better distribution of lateral forces. Contrary to the belief of many, waffle slabs don’t necessarily reduce material usage (and consequently dead load of the building) however, because overall thickness […] Read More

Masonry construction dates back thousands of years. The builders of the past, took advantage of compression strength of stone and were still able to build amazing structures, without even possessing the technology to take on tensile forces, which only became possible in modern times with steel. In our age though, masonry is also combined with reinforcing steel, to make it much more ductile and resistant to loads. Masonry can be stone or brick. Today’s masonry is mainly in the form of manufactured bricks, such as CMU – Concrete Masonry Units, which are also reinforced with steel bars. From now we will mean brick masonry in this post. Both stone and […] Read More

This is one of the posts in a series of our posts that we discuss failures. Also check out the other posts in constructmagazine.com, where we discuss failures in different contexts of civil engineering. A Brief Introduction of Earthquakes vs. Structures: Earthquakes are very important aspect of most design in civil engineering, and for any type of structure. The fundamental earthquake principles as it applies to structures are of course the same, although there are specific items that apply to each structure. Here we will discuss earthquake related failures in buildings. Earthquakes result from movements of large land masses, which in turn affect structures, by making them move too. Since […] Read More

Structural engineering is a major branch of civil engineering, and realistically the first thing that comes to mind of many, when the words civil engineering are mentioned. It deals with designing the body of all types of structures and their supplementary components, connections, attachments per the criteria given in codes, to ensure public comfort and safety. As we mentioned in the previous post in Construct Magazine, failures in civil engineering, structures can fail in so many ways but they can all be grouped under several categories. Let’s list them below… Structural Failure Types in Materials and Members: Structural members can fail as a result of many reasons such as: Yielding […] Read More

Engineers make assumptions all the time. All these assumptions are backed up by logic and theory, so instead of pursuing exact values, in civil engineering often times we are okay with close enough values, as long as the results are within acceptable limits and we can justify it with relevant proven theory. Doing so, saves a great deal of time and effort, which makes developing theory or designing and solving problems possible in reasonable amount of time and with reasonable effort. Let’s randomly list some examples below. These are structural examples but the same kind of approach applies to any branch in civil engineering and other engineering disciplines as well. […] Read More

For non engineers, structural analysis may seem like an overly complex subject. A person who is not a civil engineer will never be required or even allowed to solve a real structure, but it is still good to give some general idea for learning. This came to my mind when I heard a question once, from a nonengineer, who drew sketch of a really simple structure and asked if we solve this member by member such as column by column, slab by slab and beam by beam. This is of course not correct and civil engineers know that it doesn’t work that way… So for people who are not civil […] Read More

In seismic analysis of structures, Equivalent Static Analysis and Response Spectrum Analysis are two methods that analyze the elastic behavior of a structure, in other words, the behavior of the structure without considering any yields (plastic hinges). But how do they differ? Equivalent Static Analysis is the simplest most straightforward analysis, which will either suffice for simpler structures or you need to do anyway to get a feel for how would it be if the loading was static and the structure remained elastic. This method is good for short period, stiffer structures such as short buildings. Here the building is not tall enough for instance, to meaningfully produce higher vibration […] Read More

In this post we will look at various aspects in structural analysis and modeling of Masonry structures. Read More

This is a very useful method, which is also allowed by AASHTO or bridges and ACI 318 when designing concrete bridge and building structures respectively. By making use of this method, the stresses especially in members such as deep beams can be more realistically represented. The struts here represent the imaginary compression members of a truss and ties are the imaginary tension members. We place reinforcing steel in place of tension members. To be able to correctly construct a strut and tie model requires good understanding of how the structure works. Read More

We must consider earthquake loads when analyzing all members of a structural system. A structure is a whole unit, inseparable from each other. One effect on one member has effect on other members. Therefore we can not just isolate beams and say “earthquake loads are lateral so why do we analyze beams for earthquake” At the most basic level, the beams hold the columns together laterally and determine the sway amount of the structure, not to mention the torsion effects that the columns and shear walls resists and working together with the beams while doing so. In short, the structural frame of a building is a whole system that takes […] Read More