The influence of the critical zone model of the structural element on the seismic response of the building

U radu je promatrana sedmerokatna armiranobetonska zgrada s ciljem određivanja utjecaja modela kritičnog područja na potresni odziv zgrade. Pod pojmom kritično područje podrazumijeva se područje plastičnog zgloba, a u ovom radu to područje je definirano za stupove i grede. U tu svrhu u računalnom programu SAP2000 izrađena su dva modela konstrukcije, odnosno dva modela s različito definiranim kritičnim područjima konstrukcijskih elemenata. U modelu 1 kritična područja stupova i greda definirana su preko fiber elemenata, a u modelu 2 preko koncentriranih plastičnih zglobova. Tako definirani modeli su opterećeni serijom zapisa potresa i monotono rastućim bočnim opterećenjem kako bi se mogao utvrditi potresni odziv zgrade. Nakon provedenih proračuna, rezultati su uspoređeni s eksperimentalnim ispitivanjima te su na temelju usporedbi proračuna izvedeni zaključci o utjecaju modela kritičnih područja na potresni odziv zgrade. Proučavanjem odziva zgrade utvrđeno je da model 1 (fiber elementi) rezultira većim silama, pomacima i naprezanjima pri potresnom opterećenju. Dakle, kritična područja s raspodijeljenom plastičnosti (fiber elementi) rezultiraju kritičnijim ili nepovoljnijim utjecajem na potresni odziv zgrade. S druge strane, model 2 s koncentriranim plastičnim zglobovima uglavnom rezultira manjim silama i na taj način konstrukcija ima manje pomake i naprezanja. Prije provedbe ovih proračuna izvršena je provjera valjanosti numeričkog modela. Taj postupak je proveden usporedbom rezultata analitičkog i numeričkog proračuna pri čemu su uspoređeni periodi osciliranja, vertikalne reakcije, moment savijanja i uzdužne sile. Takva provjera je vrlo važna jer se na taj način osigurava ispravno modeliranje konstrukcije na kojoj se temelje svi ostali proračuni. Provedeni proračuni mogu se svrstati u praktični dio rada, dok se u teorijskom dijelu rada objašnjava pozadina svih postupaka i proračuna. Promatrani model zgrade ispitan na potresnoj platformi u Nacionalnom istraživačkom centru za potresno inženjerstvo u Tajvanu te je na temelju tih rezultata provedena usporedba proračuna.The paper observes a seven - storey reinforced concrete building with the aim of determining the influence of the critical area model on the seismic response of the building. The term critical area means the area of a plastic hinge and in this paper this area is defined for columns and beams. For this purpose, two construction models were created in computer program SAP2000, ie two models with differently defined critical areas of structural elements. In model 1 the critical areas of the columns and beams were defined as fiber elements and in model 2 as concentrated plastic hinges. Thus, the models are loaded with serial earthquake records and monotonically increasing lateral load in order to be able to determine the seismic response of buildings. After the calculations, the results were compared with experimental tests and based on the comparison of the calculations, conclusions were drawn about the impact of the critical area model on the seismic response of buildings. By studying the response of buildings, it was found that model 1 (fiber elements) results in greater forces, displacements and stresses under seismic loading. Thus, critical areas with distributed plasticity (fiber elements) result in a critical impact on the seismic response of buildings. On the other hand, the model 2 with concentrated plastic hinges result in less forces and stresses and thus the construction has less displacement. Before verifying these calculations, the validity of the numerical model was performed. This procedure was proved by comparing the results of analytical and numerical calculations, slowing down the periods of oscillation, vertical reactions, bending moment and longitudinal silence. Such a check is very important because it ensures the correct modeling of structures on which the topics are all other calculations. The performed calculations can be classified in the practical part of the paper, while in the theoretical part of the paper the background of all procedures and calculations is explained. The observed building model was tested on a seismic platform at another seismic engineering research center in Taiwan, and a budget comparison was made based on these results