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The analysis conducted in the earthquake regions after Marmara Earthquake on August 17, 1999 have proved that the damages in the structures occurred due to the workmanship, material, static, system and technical faults along with the groundwork problems.
One of the most important reasons occurred in the structures is the faults in the static system. Heavy damages have been occurred in the joints due to the failure to place the stirrups at the required intervals, to put stirrups at the colon-beam joints or insufficient placement of them without complying with the constructive rules prescribed by the Regulation about the “structures in the disaster regions”.
In some of the buildings, the weak colon and strong beam effect due to the failure of the joints to have the required rigidity lead collapses in these points, and all stories fell down one to another. This fact led many deaths and damages. It is of great importance to place fitting and stirrups duly at the joints.
The width of the façade of the narrow façade is around ~4 m and the height is around ~16 m. The incompatibility between the façade and the height is quite interesting. As it is seen in the photograph, non existence of a basement, the weak rigidity of the structure, the location of the structure on the corner, and the hammering effect from the adjacent building led the separation and collapse of the building. In this example, the foundation waves due to earthquake waves caused the collapse of the structure. In the structures with such narrow façades in the corner plots, the construction permit should be granted for lower height structures or the plots should be combined with the adjacent plots, and more rigid structures with wider façades should be applied. The structures with narrow façades and multiple stories at the head of the block or built as double structures shall expose less rigidity.
The hammering effect on the structures at the head of the edge of the block causes collapsing. The structure could not stand against collapsing due to non existence of the basement, too narrow façade and relatively more height. The depth of the foundation of the structure should be at least 1/6 of the height.
The depth of the foundation of a structure should be at least 1/6 of the height. In a six-story building there should be a foundation at a height of, at least, one basement; however since the foundation is only 1 m and the façade is too narrow, the collapse occurred. In this example, the hammering effect from the adjacent building facilitated the collapse.
As a result of more height of the stores in the ground floor, fitting flows occurred at the lower and higher end of the colons. As a result of the insufficient colon thickness and stirrup placement, heavy damage is observed in the building. The existing irregular curtain colons at the back saved the building from complete collapse.
Due to the more height of the store in the ground floor, the concrete on the upper end of the colon has been crashed and the vertical fittings have flown and bent due to the failure to compact stirrups. The cross sections of colons are weak, and colon windings are insufficient.
In this picture, the shifting damage occurred in the upper winding area is observed. The winding fittings are not sufficient. The horizontal constructive beam connecting the colons to each other at the suspended floor’s height has increased the damage with short colon effect.
Crushing of the concrete and flow of the fitting are observed at the upper end of the colon at the ground floor under crushing and axial pressure. It is seen that the vertical fitting on the colon is not enough, and there is no stirrup compaction at this area. Here it is clearly seen that the compaction of the stirrups is very important.
At the upper end of the ground floor colon, it is observed that the colon stirrups are collapsed one to another due to weak binding. During the ready mix concrete pouring through pump, the fast concrete pouring from the pump may lead the collapse of these stirrups; and these stirrups should be connected at the required intervals.
Crushing of the concrete and flow of the fitting are observed at the upper end of the colon at the ground floor under crushing and axial pressure due to the height of the store in the ground floor. In the heavily damaged building, the fittings are not suitable with the structure. Static system is not suitable. The concrete quality is not good enough. And the adjacent building at the right could not act rigidly against collapse, and has been damaged heavily due to the hammering effect, narrow façade and non existence of a basement floor. Major damages occurred in the structures due to the existence of errors consecutively.
Heavy damage is observed through Crushing of the concrete at the joint section of the colon and the beam. It is seen that no stirrup compaction was conducted at the continuance of the colon vertical irons projected in to the beams and joint sections of the colons and beams. The cutting cracks at the beam has formed 45° angle with the axis of the beam. These cutting cracks may be prevented through the application of stirrups in sufficient quantity. The burying of the ends of the stirrups to be used on the beams by bending 135° would increase the cutting capacity or the strength of the structure.
The structure was subjected to more damages due to the bending through the binding of the suspended floor beams at the upper end of the colon to the colon as one way and failure of the colons to be aligned on the same axis.
In the structure, the concrete was crushed and the stirrups were separated and together they caused the collapse of the structure.
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