## 6 Conclusions  
In this study, nonlinear analyses of an existing school building under the effect of blast loads applied from different distances were performed and the building performances were examined according to TBEC 2018. In the analyses, lead rubber bearings were used as an isolator to examine the behaviour of the structure against blast loads when it was fixed base or base isolated. The results were obtained comparatively by calculating the base shear force, storey displacements, and the amount of rotation in beams and columns. In light of the obtained data, the following conclusions were drawn. * It was observed that the lead rubber bearings used in the base isolation were effective in damping the explosion effects, damping the impact loads by reducing the interstorey drift and reducing the base shear forces on the structure. * When the base isolation was evaluated according to nonlinear methods, it was seen that the base isolation reduced the reaction of the building against explosion effects,  
Figure 15: Comparison of base-isolated and non-isolated structures performance levels: (a) Performance analysis 1; (b) Performance analysis 2.  
changed the mode shape of the building, and affected the plastic rotation rates in the building. * Considering the nonlinear behaviour, plastic rotations concentrated on the base storeys in the non-isolated structure helped to reduce the explosion effect by dispersing to the upper storey of the seismic isolated structure. * The results of the analysis coincide with the data in the tables created by FEMA (Federal Emergency Management Agency) for building design against terrorist attacks. (FEMA 427-426-430, etc.). * It has been observed that the strength of structures to resist the effects of explosions is affected in different ways at different distances. The fact is that isolators do not help to resist the effects of explosions at close range, while isolators do help to resist the effects of explosions at long distances. * In this study, it was observed that base-isolated structures, not designed for blast loads but only for seismic loads, performed better than fixed-base structures. This suggests that, in areas where isolators are not used and where the seismic risk is low, the use of isolators can be effective in reducing the effects of explosions. * The determination of safe explosion distances is of great importance in evaluating the effects of explosions. For instance, shelter walls designed for base-isolated structures require less distance compared to walls designed for fixed-base structures. In densely populated areas where it may not be possible to widen the safety area, the use of isolated structures is seen as advantageous. The protection of people and buildings against blast loading is very important. Thus, this study has been proposed using existing guidelines for blast load prediction and blast resistance performances of structural components, building base isolation effectiveness under the blast loading. Since the structures under the effects of the explosion are damaged locally on the basis of element, the collapses in the structural system elements can cause failure in the structure. Base isolation causes some general structural damage by distributing the loads at certain rates under the effects of explosion. In this case, more realistic approaches can be made for the damage estimation of the members by using traditional methods compared to structures without seismic isolation. Since explosions cause different effects than earthquake loads, they also affect the behaviour in structural members. The evaluation of the explosion effects according to the seismic regulations can be done by considering the ductile behaviour of the elements. However, under the effects of explosion, it may be possible for the structural members to become brittle. E.T. and O.K. contributed to the design and implementation of the research, to the analysis of the results and to the writing of the manuscript. All authors have read and agreed to the published version of the manuscript.