In this article, we will examine how an earthquake resistant building should be built, mistakes and deficiencies made in the architectural design phase and what needs attention.
Buildings are generally designed to carry vertical forces. In other words, the walls, furniture, people, in short, the forces under the effect of gravity are vertical loads. However, the earthquake affects buildings in a horizontal plane.
Factors Affecting Building Design
- Architectural design
- Local Soil And Geotechnical Conditions
- Building Materials Used
- Earthquake and Its Properties
- Carrier System Design
Experiences gained from earthquakes all over the world reveal that earthquake resistant building designs start in the architectural design phase. The plan of a building is important for the structural system. Placement of the column beams depends on the possibilities provided by the architectural plan. In addition, the selection of building materials and the effect of the carrier system should be examined in terms of earthquakes.
Some Incorrect and Incomplete Design Decisions In Terms Of Architectural Design
- Columns and beams to be made smaller than necessary in order to be hidden in partition walls.
- Simple and unsymmetrical building forms in plan and height.
- Continuous load-bearing walls and large volumes without large cross-sectional columns when a wide, spacious and unobstructed area is desired.
- Exterior spaces.
This and similar approaches make it difficult to create an earthquake resistant carrier system.
There are two conditions that the building must comply with in terms of earthquake resistance:
- The Structure Should Be Light: Lightness of the structure will minimize earthquake effects. Filling and partition walls in a reinforced concrete structure should be used to lighten the structure. Large openings in the plan should be avoided.
- The structure should be as symmetrical as possible: Earthquake resistance can be provided more easily in simple and symmetrical structures.
General Principles in Earthquake Resistant Design
Issues to be Considered in Determining the Framed Carrier System in the Plan
- Columns must be placed in an axle system. Otherwise, they will cause negativity as they cannot transfer their effects to another.
- The wheelbase should be as equal as possible.
- Columns should be placed perpendicular to the facade in the plan. In this way, the columns will better transfer the horizontal effects to the other.
- Columns must be attached to beams in both directions.
- The minimum column width should be bw = 300 mm.
- Columns should be placed equally in two axes. It should be half in one direction and half in the other. Otherwise, the balance will gather to one side and sprains occur on the sides where the rigidity (balance) is weak.
- The column in one floor should continue to the foundation and the loads should be safely transferred directly to the floor.
Issues to be Considered in Settling of Shear Walls
Increasing the number of floors in buildings requires the use of elements that will provide the necessary horizontal rigidity. In this respect, curtains are elements used to pull the rigidity to the required value against horizontal loads.
The main purpose of curtains is to gain sufficient (rigidity + strength + ductility) to the structure.
- As in column systems, curtain walls should be placed in an axle system and their axle spacing should be equal or close to the same.
- Curtains should be placed equally in two directions and the beams should be ductile.
- Curtains should be overlaid on the floor of the building. Otherwise, the beams in their own plane act as carriers, this is definitely not allowed.
- Curtain thickness should not be less than 200 mm.
CONCLUSION AND RECOMMENDATIONS
Preliminary design sketch studies in the design of the carrier system will constitute the most important stage of creating a safe structure in the next analysis stages of the project. The next stages should be determining the dimensions of the projected structural system elements and equipping them and carrying out the works to be transferred to the application.