Çok katlı çelik çerçeve türü bir taşıyıcı sisteminde eski ve güncel yönetmelik uygulamalarının karşılaştırılması

Abstract

Yüksek lisans tezi olarak sunulan bu çalışmada, her iki doğrultuda süneklik düzeyi yüksek çelik çerçevelerden oluşan 7 katlı işyeri binasının eski ve güncel çelik ile deprem yönetmeliklerine göre boyutlandırması yapılmıştır.Kocaeli Gebze'de inşa edilecek olan bina planda 40x24 m boyutlarında ve 960 m2 oturma alanına sahiptir. Kat yüksekliği 3,5 metre olan binanın zemin kotundan itibaren toplam yüksekliği 24.5 metredir. Binada kompozit döşeme sistemi tercih edilmiştir. Döşemelerin plak davranışını sağlamak amacıyla kirişlere kayma çivileriyle (stud) bağlantısı yapılmıştır.Binanın çelik taşıyıcı sistemi elemanları St52 (S355) kalitesinde yapısal çelikten oluşmaktadır. Kompozit döşemelerde C25 betonarme betonu ve S420 sınıfı betonarme çeliği kullanılmıştır.Bina taşıyıcı sisteminin statik ve dinamik analizleri SAP2000 bilgisayar yazılımı ile yapılmıştır.Tez çalışmasının ilk bölümünde bina taşıyıcı elemanlarının malzeme sınıfları, hesaplarda kullanılan yöntemler ve yapılan kabullere yer verilmiştir. Ayrıca eski ve güncel deprem yönetmeliklerine göre deprem hesaplarında kullanılacak hesap yönteminin seçilmesinde belirleyici olan yapısal düzensizlik kontrollerinin sonuçları gösterilmiştir.İkinci bölümde, bina taşıyıcı sisteminin tasarımında esas alınan sabit yükler, hareketli yükler, kar yükü, rüzgâr yükü ve deprem yüklerinin hesapları yapılmıştır. Kar yükü ve rüzgâr yükü hesapları, eski TS-498 ve güncel Eurocode-1 yönetmeliklerine göre yapılmıştır. TS EN 1991-1-3 yönetmeliğine göre kar yükü hesabında, binanın yer aldığı kar yükü bölgesi ve yükselti koşullarının yanında çatı eğim açısı, binanın rüzgâr alma durumu ve çatıda kar yükü birikmesi durumları da dikkate alınmaktadır. TS EN 1991-1-4 yönetmeliğine göre rüzgâr yükü hesabı binanın arazi kategorisi, binanın şekli ve arazinin engebe koşullarını yansıtan parametrelerle hesaplanmaktadır. Deprem yükleri hesabı ise, güncel TBDY-2018 ve eski DBYBHY-2007'de yer alan eşdeğer deprem yükü yöntemine göre yapılmıştır.Üçüncü ve dördüncü bölümlerde, binanın SAP2000 bilgisayar yazılımı yardımı ile göreli kat ötelemelerinin sınırlandırılması, ikinci mertebe etkilerin kontrolü ve bina taşıyıcı sistem elemanlarının boyutlandırılması eski ve güncel yönetmeliklere göre değerlendirilmiştir. Taşıyıcı sistem elemanlarının gerilme kontrolleri ASD (emniyet gerilmeleri yöntemi) ile LRFD (load and resistance factor design) yöntemlerine göre yapılmıştır.Beşinci bölümde, ÇYTHYE-2016'ya göre basit mesnetli kompozit kiriş tasarımı yapılmıştır. Betonarme döşeme, çelik kirişe mesnetlenen trapez enkesitli çelik sac üzerine uygulanmıştır. Çelik sac hadveleri çelik kiriş boyuna eksenine dik doğrultuda yerleştirilmiştir. Hesaplarda kullanılan başlıklı çelik ankraj ve çelik döşeme sacı konstrüktif esaslara uygun olarak belirlenmiştir.Altıncı bölümde, TS-500'e göre tasarlanan radye temelin zımbalama dayanımı kontrolü, zemin emniyet gerilmesi kontrolü ve donatı hesabı yapılmıştır. Radye temel 80 cm kalınlığında seçilmiş ve her iki doğrultuda 1'er metre ampatman olacak şekilde (26m x 42m) ebatlarında belirlenmiştir. Radye temelde C25 betonarme betonu ve S420 sınıfı betonarme çeliği tercih edilmiştir.Yedinci bölümde; tali kiriş-kiriş birleşimi, kolon-kiriş birleşimi, ankastre kolon ayağı ve kolon eki detaylarının hesapları yapılmıştır.Sekizinci bölümde, eski ve güncel yönetmeliklere göre elde edilen sonuçlar karşılaştırılmıştır.

In this study, which is presented as a master of science thesis, 7-storey steel building that comprises of high ductile steel moment resisting frames in two directions is designed according to both old and new steel and seismic design codes. The building which will be constructed in Gebze district of Kocaeli city has 24mx40 m dimensions on plan view with 960 m2 floor area. Each story height is 3.5 meters and the total height of the building measured from ground level is 24.5 meters. It is preferred to use composite slab in building system. In order to provide the slabs' behaviour as plates, beams are connected with studs.St52 (S355) quality structural steel is preferred for all structural members of the steel frame building. For composite slabs, C25 quality concrete and S420 quality reinforcement are used.For dynamic analysis and static analysis of the supporting structural members, SAP2000 program is used.In the first part of the thesis study; definition of the material classes of the structural members, methods and assumptions that are used in calculations are mentioned. Additionally, results of structural instabilities that are effective on determining calculation methods used both in the old Turkish seismic design code (DBYBHY-2007) and the new Turkish seismic design code (TBDY-2018) are stated. In the second part of the thesis study; dead loads, live loads, snow loads, wind loads and earthquake loads which are taken into consideration for the design of structural members are calculated. Both the old TS-498 and the new Eurocode-1 codes are used for the calculation of snow loads and wind loads. Calculation of snow load according to TS EN-1991-1-3 code, apart from the old code's conditions are also considered such as roof slope angle, wind exposure condition of the building, accumulation of snow on the roof. Calculation of wind load according to TS EN-1991-1-4 code, land cathegory of the building, geometry of the building and parameters related to orography play an important role. Earthquake loads are solved applying the method of equivalent earthquake load available in both the old and the new Turkish seismic design codes. In the old seismic design code, it was defined four different earthquake hazard regions. For each earthquake hazard region, earthquake hazard was considered to be constant which is presented with only one parameter, A0 (effective ground acceleration coefficient). However, assuming the effective ground acceleration coefficient as a constant was not accurately enough to explain the seismic hazard. New studies in the field of earthquake sciences in recent years taught us that seismic hazard cannot truly determined. Therefore, seismic hazard is taken into consideration as a probabilistic event depending on some basic data such as active fault maps, earthquake catalogs and ground motion prediction equations. All these datas are evaluated based on the suitable statistical probability model and in considered geographical region it is calculated reach or excess size of a typical ground motion parameter at a certain time period. By taking into account the data mentioned above, Turkey Seismic Hazard Map was established with the new Turkish seismic design code in 2018. By the new seismic design code, earthquake load calculations and analysis procedures became more detailed. It will be useful to express the calculation steps of the new seismic code in this study. Firstly, it is used the seismic hazard map to obtain the map spectral acceleration coefficient at short period (namely 0.2 second) and 1.0 second period. These two map spectral acceleration coefficients were defined for the average slip wave velocity at the above reference 30 meters ground level. Therefore, these values were converted into the design spectral acceleration coefficients by multiplying local site effect coefficients. Design spectral acceleration coefficients were used to determine the graphics of horizontal design acceleration spectrum based on elastic design spectral acceleration and period. Secondly, important seismic parameters were described depending on the classification provisions available in the seismic design code. Building importance coefficients are classified into three category with building use class. Seismic design category of the building were determined depending on short period response acceleration parameter and building use class. In the new seismic design code it was defined eight building height classes based on seismic design category of the building and the height intervals. In the third and the fourth parts of the study; forces and moments obtained by using SAP2000 software program are used to specify relative floor displacements, second order effects and design requirements of the structural members applying to old and new design provisions. D/C (demand / capacity) ratios of the structural steel members were calculated under the specified load combinations of both the old and the new steel design codes. According to the old steel design code, namely TS-648, normal stress checks and shear stress checks of steel structural members were done to determine D / C ratio. The new Turkish steel design code (ÇYTHYE) which became valid in 2016 recommends to use one of the two design methods: LRFD (load and resistance factor design) and ASD (allowable stress design). ASD method is based on the principle that is developped stresses in the structural members should not exceed approximately 50-60 percent of elastic strength limit. LRFD method is based on the principle that is resistance (strength) of the material is reduced by some constants while applied loads are increased by strength coefficients. In this thesis study, LRFD method was preferred. Bending moment strength, shear force strength and axial force strength of structural members were checked to obtain D / C ratio based on LRFD method. Additionally, deflection check under vertical loads and lateral support calculation were done for beams by taking into account the old and the new design codes. In the fifth part of the thesis study; simply supported composite beam is designed according to the limitations and rules available in ÇYTHYE. Concrete slab is applied over the corrugated steel sheet connected to the steel beam. Composite beam strength calculations were done for the two different processes. During the construction process, it was checked the vertical deflection of the composite beam under fresh concrete cover load and live load. For the usage process, it was controlled the strength under the composite beam behaviour. Corrugated steel sheets are placed perpendicular to the longitudinal axes of steel beam. Headed steel studs and corrugated steel sheets are suitably designed in accordance with constructive rules.In the sixth part of the study; mat foundation is designed according to TS-500 (requirements for design and construction of reinforced concrete structures). Thickness of the foundation is chosen 80 cm and dimensionsions of the foundation is (26x42) m with 1 meter enlargement in both two directions. Mat foundation is checked for punching strength and allowable bearing stress and is determined required reinforcement using TS-500. It is assumed that allowable soil stress value is 300 kN/m2 and soil spring constant is 30000 kN/m3. For mat foundation, C25 quality concrete and S420 quality reinforcement are preferred. In the seventh part of the study, secondary beam-beam connection, high ductile column-beam connection, fixed-ended column base and column-column connection designs are done using new steel and seismic design codes. The strength calculations of all connection types are solved by LRFD method. Two sided clip angle is used as secondary beam-beam connection. The part of the clip angle on the secondary beam is connected with bolts and other part on the beam is connected with fillet weld. The bolt class was determined as high strength bolt with 20 mm diameters. Fillet weld thickness is chosen as 5 mm depending on the constructive rules in new steel design code. Column-beam connection is chosen as welded unreinforced flange-welded web moment connection that is available in the new Turkish seismic design code. In this type of connection detail some specified limitations were satisfied such as plastic hinge location, beam cross section height, ratio of beam span and cross section height, beam flange thickness, column cross section height, weld access hole for full penetration butt welding, type of flange plate weld and protected capacity zone. As a result of the strength calculations, it was required to use doubler plate doubler plates in panel zone and continuity plates along the two beam flange edges. Then, fixed-ended column base design calculations were done. In thesis study, due to being steel moment resisting frame system in two perpendicular directions, columns were subjected to normal force, shear force and two-way bending moment that made difficult to obtain location of the neutral axis fixed column base were difficult. Therefore, fixed-ended column base design were designed as finite element with the help of SAP2000 software program. In this finite element model, elastic compression springs were used in order to take into consideration interaction between mat foundation and base plate. It was placed pinned supports where anchor rods were available to determine tensile forces. Shear forces generated in fixed-ended column base connection with mat foundation were transmitted using square box sections. For column-column connection, it was preffered full penetration butt welding.In the last part of the study, results of the thesis study according to the old and new codes are compared.