Design of a reinforced concrete building according to Turkish, European and American regulations

The importance of structural design of buildings with earthquake resistance is increasing in today's world. Earthquake resistance structure are designed especially at the countries on seismic zone. With nowadays technologies and structural analysis programs design of earthquake resistance structure is easier and more accurate than before. With the help of programs more correct results are obtained in less time. As civil engineers, understanding and applying design of earthquake resistance structure is our professional liability. For preventing total collapse during earthquake for limiting permenant damage and avoid loss of life is possible with proper controls on structural design and understanding and applying published regulations of countries. At this graduate thesis structural analysis program is used. Turkish regulations DBYBHY and TS 500, American regulations ACI 318-11 and for earthquake loads ASCE/SEI 7-10 and European regulations Eurocode 2 and Eurocode 8 is used on a reinforced concrete structure with an ground level and ten regular floors. By investigating required conditions of different regulations, earthquake resistance structure is designed and the results are compared. The building which is a designed structure with a ground level and ten floors on seismic zone one. The structure is a residential building with 3 meter story height. The structural system consists of frame-equivalent dual systems. The material used in construction is C25/S420. The first section of this thesis consists regulations used in this work and purpose of the paper. As Turkish regulations the code on the buildings to be built in the earthquake zones (DBYBHY) which has published by Ministry of Public Works and Settlement Government of Republic of Turkey in 2007, TS500 rules of design and calculation of Reinforced Concrete Structure which has published in 2000 and TS 498 Calculation values of the loads to be taken in the dimensioning of structural elements are used. When arranging reinforced concrete structural design, European regulations Eurocode 2 and when designing buildings with earthquake resistance Eurocode 8 is used. As American regulations, Building Code Requirements for Structural Concrete and Commentary (ACI 318-11) is arranged in 2001 by American Concrete Instute (ACI) which organizes the rules of reinforced concrete structural design is used. For earthquake resistance structural design "International Building Code (IBC)" which is revised in 2012 and "Minimum Design Loads for Buildings and Other Structures (ASCE/SEI 7-10)" published in 2010 are used. In the second section of the study, structural irregularities are explained in relevant regulations. Seismic calculations are explained in detail. According to building properties relevant calculation methods, whether lateral force analysis or modal response spectrum analysis is choosen. The parameters used in seismic calculations are explained. Also ultimate state design method requirements of regulations are compared in this section. The third part of this work gives informations about the building which is going to be designed. The historical building called "Sokullu Mansion" which is used in the study is located in Acıbadem Kadıköy. The building belongs to Yapı Merkezi Construction lnc. After some revisions on the floor plan, it is acccepted that the number of floors are increased. The building is a designed structure with a ground level and ten floors and structural system consists of frame-equivalent dual systems will be projected as a reinforced concrete residential buildings. The length of the building at x direction is 23 m and at y direction it is 16,50 m. Area of the total floor is 380 m2. Floor slabs works in two dimensions. the thickness of the foundation system is 1 meter. The foundation has been choosen as raft foundation. The foundation expand one meter on both sides of the floor plan. The length of the raft foundation at x direction is 25 m and at y direction it is 18,50 m and area of the total foundation area is calculated 462,5 m2. Also informations about structural analysis program is given in this section. In the forth section of the study, analysis of the building is started. First, information of working mechanisim of the floor slabs are given. The thickness of the slabs are calculated according to TS 500. Then, design loads are determined by load analysis. Finally, frequency, period and angular frequency values of different mod shapes are obtained as a result of the analysis. Also mass of the stories and mass moment of inertia for each story have been calculated in this section. In the fifth part of the study detailed seismic calculations according to different regulations are done. The required load combinations of the regulations are defined and compared. As stated in ASCE/SEI 7-10 vertical seismic loads are considered. Eventhough in Eurocode 8 vertical seismic loads are considered, buildings does not include the properties of Eurocode 8 classification about using of vertical components of the earthquake so only horizontal components is used at load combinations. And DBYBHY does not include vertical effect of earthquake action. As a result of analysis, possible irregularities are checked under the seismic load combinations at the designed structure. For bending end shear calculations controls required by high ductility class buildings are done separately according to the regulations. Reinforced concrete calculations of S04 and S02 columns with K109 and K110 beams of B-B axis and P02 wall at 4-4 axis are done on the buildings and shear and longitudinal rebars are calculated and suitability to regulations are shown. Reinforcement details are shown after the calculations. Here divergently than other regulations spectral acceleration values should be considered at ASCE/SEI 7-10 design. Generally it is calculated according to importance and ductility class of the building. At ASCE/SEI 7-10 MCER maps which shows spectral acceleration values S1 and SS of the all country is used for determining seismic design category. Design spectral acceleration values by multipying the map values S1 and SS, which are prepaired according to soil class B, with relevant soil constants Fa and Fv and decreasing with specific ratio. In the sixth section of the paper, acording to different regulations, the seismic calculations and reinforced concrete calculations are summarized and the results are shown at tables. Base shear forces under seismic forces, periods of the structure, design interstory drifts, effective seismic weight and second order effects have been checked and compared. The design strength is calculated by the calculations done acoording to TS 500 and Eurocode 2, design strength of elements are divided to material strength coefficient γ_s, γ_c. On the other hand ACI 318 design strength is calculated by multiplying nominal strength with coefficient Φ. Similarly design axial forces, shear forces and bending moments are calculated. According to Turkish and European regulations, at the seismic calculations, effective seismic weight are calculated by adding dead loads with live loads which is decreased with live loads coefficient factor n. According to the American regulations, except some special cases defined in regulations, live loads are not considered at the calculations of effective seismic weight. Design of the Turkish and American regulations are similar. Eventhough, Eurocode 8 and DBYBHY multiply displacements with q (structural behaviour factor) ASCE/SEI 7-10 seperatly than structural behaviour factor, this regulation uses deflection amplification factor Cd and divides to importance factor I of the building. While designing wall boundary elements according to Eurocode 8 and ASCE/SEI 7-10, axial forces and according to this force, compression stress is considered. Eventhough these regulations consists these elements, Turkish regulations only consider geometrical properties of the wall. This is an important result to acknowledged. Also some of the reinforcement results have been calculated same for each type of regulations. Because of minimum reinforcement ratio of column is equal for in all three design codes, longitudional reinforcements of the columns have been choosed same. On the other hands shear rebar of the colums, length of ciritical regions and spacing of the transverse reinforcement according to critic regions have been selected different due to code requirements. The worst results are obtained by Eurocode regulations. Eventhough Eurocode 8 regulation provide the safer design, it is the most expensive solution. And least conservative results and most economical design have been obtained by using Turkish Seismic code 2007.