The issues with the R factor have been discussed for many years. Determining the behavior of a structure, consisting of hundreds of columns, beams, and thousands of nodes, during an earthquake with a single coefficient seems too good to be true.

For example, as the axial load on a column increases, its ductility decreases. So, how can a ground-floor column and a 5th-floor column be analyzed with the same R factor? Or can the ductility of a long beam and a short beam in the same building be the same? Does the panel zone ductility, where columns and beams of different sizes intersect, remain constant throughout the entire structure?

How can we be sure that the plastic hinges formed during an earthquake will distribute uniformly across the structure, as assumed by the R factor? What if all the hinges concentrate on the first floor, as American engineer Dirk Bondy has been explaining for years, pushing the structure into a mechanism state?

In the example below, a 5-story building is analyzed using the equivalent seismic load method, and all code requirements, including the strong column-weak beam rule, are applied. In step 7, before the roof reaches 2% drift, hinges form both at the bottom and top of the ground-floor column. According to the code, hinge formation at the base (support) is acceptable, but other hinges must form in the beams to prevent the structure from reaching a mechanism state. However, the moment diagram at the top of the ground-floor column shifts significantly in one direction, which cannot be captured by linear analysis.

When we examine the collapse patterns of structures during earthquakes, could these hinges, in addition to weak-story and soft-story irregularities, also be a cause of collapse?

In performance analysis, additional elements are defined at locations where hinge formation is expected during an earthquake. Each component of the structure—beams, columns, braces, connection zones, etc.—is individually evaluated in terms of ductility.

The results reveal the performance of every element at various earthquake levels, highlighting the weak and critical points in the structure. These weak points can then be strengthened as needed.

After any earthquake, it becomes clear:

• Whether the structure can be used immediately,
• The extent of damage that will occur,
• Whether the damage can be repaired.