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Design of new buildings from a structural perspective

In addition to imagination and conceptual thinking, structural planning and design involve extensive knowledge of practical aspects, such as recent design codes and bylaws, as well as a great deal of experience, institution and judgment.

Buildings must meet the efficiency requirements for which they are intended, and they must be durable for the duration of their intended lives. Structures are categorized into two types based on their design:

• Structural Design
• Functional Design

Structures designed for functionality

It is of utmost importance that the structure be constructed serves the primary purpose for which it is intended and looks pleasing. Neither the inside nor the outside of the building should be a sad place.

In the case of community halls, cinema theatres, etc., the functional planning of a building should take into account lighting, acoustics, ventilation, ventilation, lighting, and unobstructed views.

The Structural Design

In order to start the structural design process, it is necessary to select the form of the structure. The design of a structural structure is an art and science involving understanding the behavior of structural members under loads and designing them with economy and elegance so that they are safe, serviceable, and durable.

What are the stage of Structural Design?

During structural design, the following stages are involved.

• Firstly, the structural planning is made
• Forces acting on loads and their computation
• Figure out the Analysis methods
• Member selection
• Preparation of schedules, details, and drawings

Structural Planning

The structural planning of the building frame begins after an architectural plan is obtained. In order to determine this, we must determine the following.

Proper Orientaion and Positioning of columns: Corners of a building, as well as intersections of beams and walls, are ideal locations for columns. Beam bending moments can be reduced by positioning columns in the right place. Beams with longer spans should be avoided. Make sure the centre-to-centre distance between columns is as small as possible.

Ensure that columns are not projected: Columns projected outside of the wall should be avoided in the room, since they not only look bad, but also obstruct the use of floor space, making it difficult to place furniture flush with the wall. There must be no less than 200mm width between the column and the wall to prevent it from looking slender.

There should be a substantial reduction in the column spacing on each floor, as this will reduce the load on the columns and prevent the need for large sections for columns.

The depth of the column should be perpendicular to the major bending axis or within the plane of bend. The purpose of this is to increase the moment of inertia, thereby increasing the moment resisting capacity. As a result, the column's load carrying capacity will be increased as well, since the Leff/d ratio will be reduced.

The positioning of the beams

The walls should normally be supported by beams or heavy concentrated loads should be supported by beams so that these loads do not directly impact the slabs.

Deflection and cracking criteria should be avoided by avoiding larger beam spacings. Consequently, a larger span leads to greater deflection (deflection varies directly with the cube of the span and inversely with the cube of the depth i.e. L3/D3).

The Structural Designs of the Foundations

Based on the column's load and the soil's bearing capacity, the type of footing is determined. Large variations in soil are more likely to occur under the foundation. A building's foundation may be made of soft clay or hard murum, depending on the type of soil. It is possible for the nature of soil and its properties to change with the seasons and weather, such as swelling during wet weather.

Moisture content increases cause soil bearing capacity to decrease, resulting in differential settlements in certain soils.

In order to determine soil properties, a survey is required. It is usually recommended to use isolated column footings to support framed structures, unless there are large depths involved, in which case pile foundations may be appropriate.

In the case of very closely spaced columns and a low bearing capacity of the soil below the foundation, a raft foundation may be an alternative solution. There is the option of providing a combined footing or a raft footing for a column on the boundary line.

To get more details, watch the following video tutorial.

Lecturer: Engineering Learning Platform

Designing earthquake-resistant buildings: Assumptions

In order to design a structure that is earthquake resistant, the following assumptions have to be made:

• It is unlikely that an earthquake will occur simultaneously with a windstorm or Flooding.
• During an earthquake, impulsive ground motions occur that are complex and irregular in nature, changing in periodicity and amplitude over time. Since such amplitudes would need time to build up, resonances of the type observed under steady-state sinusoidal excitations will not occur.
• Whenever needed, static analysis may be used to determine elastic modulus.