Invastigation of structural system behaviours on reinforced concrete multi storey buildings

Earthquake, one of the biggest challenges for structures is very effective in our country. To make durable and earthquake resistant building, it is necessary to take advantage of past experience. Codes which are created previous collections are made use of analysis and design of structures."Specification for Buildings to be Built in Siesmic Zones 2007" is used for seismic design in our country, which is in earthquake zone. In order to do ideal design, codes should be optimized. Because in engineering, there are three basic rules which are safety, economy and aesthetic. Therefore the suitable system at the right place should be established. The main purpose of Turkish Earthquake Code design against earthquake which could occur about once in 50 years with 10% probability of exceedance design earthquake. Whereby the structure is intended to take no damage in slight earthquakes. Also in the moderate earthquakes, damage should be repairable. In severe earthquakes, it is desirable to provide safety and avoid to prevent collapse. In this study, 47 different structural models were created. Structural systems, number of storeys, seismic zones, slab types, live loads, soil and concrete classes were compared. Variation of parameter which maximum displacement in two directions, maximum value of effective relative storey drifts in two directions, maximum second-order effect indicator, period, torsional and interstorey stiffness irregularities were observed. Models sizes in plan are 24mx30m=720m2. The story height is equal to 3.0m for all models. Models were designed one floor basement surrounded with shear walls in every ten floors. There are three different seismic load calculation method which are Equivalent seismic loads method, Modal superposition method and Time increment method in Turkish Seismic Code 2007 but the most suitable method for these structural properties is Modal superposition method. In "TS500 Requirements for Design and Construction of Reinforced Concrete Structures" has some combinations which only vertical, wind, earthquake and lateral earth impulse loadings. All necassary combinations are taken into account while numerical modeling and analysis. Loads was determined according to "TS 498 Desing Loads for Buildings". Models are considered residential, building live load participation factor equals 0.3, building importance factor equals 1.0. According to Turkish Earthquake Code, there are two different ductility level of structural system; normal and high. These levels influence structural system behaviour factors. Multi-storey buildings are required to be in high ductility. Because of using in structural systems frequently, frames, coupled structural walls-frame and solid structural wall systems were compared. In order to observe variation of parameters owing to number of storeys, 10, 15, 20, 25, 30, 35, 40 and 50 storeys structures was modeled. Frame structural system was only created 10 and 15 storeys, because it is not effective after about 15th floor. To understand the seismic zone effect which are used in calculations for seismic loads, all degree of seismic zones (1.o-2.o,3.o-4.o) in Turkish Earthquake Code 2007 were compared. Because of using in slab types frequently, plate, joist and flat slab systems were compared. Plate slab system models are 18cm thick. Beam sizes vary 30cmx60cm to 40cmx80cm depending on conditions. Joist slab system models are 7cm/32cm thick and 10cm/50cm width and spacing. Beam sizes were used 60cmx32cm and 90cmx32cm depending on loads. Flat slab systems are 30cm thick. Different live loads ,which are 2 kN/m2, 3.5 kN/m2 and 5 kN/m2, was effected buildings. Thus, the effect of the change in live load was observed. To observe the local site class effect, all of them (Z1-Z2-Z3-Z4) in Turkish Earthquake Code were compared. Three different class of concretes were modeled for understanding the effect of changes in parameters. These classes are C30, C35 and C40. The thesis consists of six chapters. The first chapter was mentioned the aim of the study and issues to investigated. In second chapter, Structural system that can be used in highrise buildings were examined. That was described the characteristics of the systems. Frames, coupled structural wall-frame and solid structural wall systems were compared in terms of story displacements. So that was guidance for the selection of ideal structural system. Also effect of wind loads on multi-storey buildings is mentioned. In third chapter, it is mentioned that "Specification for Buildings to be Built in Siesmic Zones 2007". Equivalent seismic load method, mode superposition method and analysis methods in time domain were investigated. Parameters that are decisive for the design of the buildings examined and described how to use the created models. In the plan and vertical irregularities which were examined in detain in the comparison were explained. Also in this section, effective relative storey drifts and second-order effect indicator were described. There is no limitation on the maximum displacements and periods in Turkish Seismic Code but maximum value of effective relative storey drifts is required to be less than two percent. Maximum second-order effect indicator should be less than twelve percent. Additionally maximum storey drift to mean rate of storey drift should be less than 1.2 in any storey. This rule is related to torsional stiffness irregularity. In stiffness irregularity between adjacent floors, interstorey stiffness irregularity coefficient which is calculated 5% in the eartquake load eccentricity is desirably less than 2. This calculation should be made between all adjacent storeys. The fourth chapter provides information about the models. It is explained how to design models. Slab plans of all structural systems and slab types are given. Because of 47 different models, their names are coded and shown in this section. Calculations of slab weights are given. In the fifth chapter of the thesis, structural systems, number of storeys, seismic zones, slab types, live loads, soil and concrete classes were compared. Variation of parameter which maximum displacement in two directions, maximum value of effective relative storey drifts in two directions, second-order effect indicator, period, torsional and interstorey strength irregularities were observed. Related graphics are provided. It was determined difference between values. In the sixth and final chapter, comparison of the results obtained from studies are covered. Conditions on the parameters of the effect of the change has been observed. At the end of the study, it is reached many results. To touch some of these significant results, frames makes it more relative displacement on the lower floors. Whereas solid structural walls makes it more relative displacement on upper floors. Second-order effect indicator of frame systems are greater than coupled structural walls-frame systems'. Greater than 15st floor in comparison, Second-order effect indicator of coupled structural wall-frame systems are greater than solid structural wall systems'. Torsional irregularity of frames and coupled structural walls-frame systems decreases with increasing number of storeys but torsional irregularity of solid structural wall systems increases with increasing number of storeys. In terms of torsional irregularity coefficient, frame systems are smaller than coupled structural walls-frame and solid structural wall systems. In less than twenty-storey comparison, coupled structural walls-frame systems are greater than solid structural wall systems but more than twenty-storey comparison, solid structural wall systems are greater than coupled structural walls-frame systems.Plate slab systems give better results than joist and flat slab systems in terms of maximum displacement and maximum value of effective relative storey drifts in two directions. When examined torsional irregularity, plate slab systems behave better than flat slab system which behave better than joist slab system. In terms of the interstorey stiffness irregularity, joist and flat slab systems give better results than plate slab system. With an increasing number of storeys, maximum displacement in two directions, maximum value of effective relative storey drifts in two directions, maximum second-order effect indicator and period show declining growth, torsional irregularity decreases. The comparison of the seismic zone, maximum displacement and maximum value of effective relative storey drifts in two directions varies linearly depending on A0.