The first step in the structural analysis and design cycle is to create the structure's skeleton. Typically, the structural engineer would make an initial design based on the architect's plans - place the positions of foundations, columns, and beams, make sections and details for each component, and assign materials. Whatever output that may be is what we call the structural model.
Structural Model
The structural model is an engineer's solution to a structural problem.
At the start, the engineer would create a layout that one believes would be the building's skeleton. Afterward, one tests this model. Engineers must ensure that the structure supports the loads it may experience and carries out its intended purposes. If there are errors in the design, the engineer will make corrections to the structural model. This process repeats until one reaches an optimum design.
How Do Engineers Model?
The structural model would depend on the purpose, aesthetics, budget, and environment, culture, to name a few.
Let's say we are to create a frame for a house near a beach. It is wise to develop a structure NOT made of steel since it's a coastal area - prone to corrosion. Having relatively large footings and tie beams may be a great idea if the soil is sandy. If the house is one level, we won't need industrial-sized sections for beams or columns.
From our example, you can see how certain factors influence the structural skeleton. It's a skill that requires experience.
Components
Let's recall that a structure is an assemblage of multiple components. Generally, there are four: (1) members, (2) joints, (3) supports, and (4) panels. Together, engineers arrange these components in a fixed reference to create a safe and functional structure.
Members
A structural member is a one-dimensional relatively long, slender object that carries loads. Physically, it can represent a simple beam, column, bracings, or truss member. A member usually consists of a cross-sectional shape running along two points. It can vary on a lot of properties:
Another aspect, aside from their properties, is their behavior under structural loads, which would depend on the type of structure.
Joints
Joints are the end or intersection points of members. Other similar names for it are nodes or connections.
These components behave based on rigidity which can be rigid, semi-rigid, or flexible.
Supports
Supports are objects used to carry structural loads. In real life, these can be the building's foundation or a retaining wall. It can be a simple point applied to a joint, a line segment along a member, or a plane surface along panels.
Aside from carrying structural loads, it also controls deflection - an often understated idea. For example, a fixed support at the structure's base would prevent the building from moving or rotating at that particular point.
Panels
Panels (or shells) are two-dimensional surfaces. These can be slabs, walls, roofs, and claddings, to name a few. In terms of function, they are similar to members - components designed to carry loads.
Summary
The structural model is an engineer's solution to a structural problem.
The structural model would depend on many factors.
Generally, there are four components of a structure: (1) members, (2) joints, (3) supports, and (4) panels.
Members are relatively long and slender objects that carry loads.
Joints are the end or intersection points of structural members.
Supports are objects used to carry loads. In addition, these control the structure's deflection.
Panels are surfaces designed to carry loads.
