Investigation of reinforced concrete buildings with hollow block slab analyzed in national structural analysis software using etabs

In Turkey, national structural analysis software such as Sta4Cad, İdeCAD Statik, and ProtaStructure, which are capable of generating shop drawings, is employed to design reinforced concrete structures. In order to obtain a flat ceiling surface and increase the floor area without vertical structural elements, hollow block slab that is filled with a proper material is widely used by designing beam and slab depth as equal size. The hollow block slab has architectural benefits regarding the effective usage of floor height and interior design of buildings. This slab type is also called "asmolen slab system" with reference to the name of the filling material used to facilitate formwork application between ribs. Another advantage of the hollow block slab is reducing labor costs and duration of construction due to less formwork compared to other slab systems. By reducing the beam depth and increasing the beam width, shallow beams that provide sufficient bending, shear, and punching shear capacity are designed. In this slab system, the thickness of the slab is the distance between the top of the slab and bottom of the rib, and the thickness of the hollow block slab is larger than the thickness of the solid slab which is widely used. As a frequently utilized slab system in Turkey, a hollow block slab system is applied as a one-way slab through a thin concrete slab between ribs. The aim is to investigate and compare the seismic behavior of reinforced concrete structures with hollow block slab, which is widely used in Antalya region and Turkey, that are with and without a shear wall, orthogonal and non-orthogonal frame, and shear wall and moment frame in accordance with Turkish Earthquake Code-2007 (TEC) and TS 500 (2000) in national structure analysis software according to Turkish Building Earthquake Code-2018 (TBEC) using ETABS. Although the multi-story buildings with hollow block slab investigated are located in Antalya region, the building having the same type of slab system is commonly observed across Turkey. It is noted that designing such structures in earthquake-prone areas needs more carefully modeling the structure. This is because in this study, it is aimed to investigate the modeling errors that can be made in the modeling process by using ETABS and to produce recommendations. In this regard, it is also aimed to contribute to the correction of the issues in the codes of some other countries (ACI 352-02, 2002) which are not included in TBEC- 2018. Thus, it was encouraged to construct buildings that exhibit proper seismic behavior. In addition, it is emphasized that especially regarding non-orthogonal axis, some additional measures should be taken in calculation and design in the code. A total of six buildings, two for each software with the different intended use, with hollow block slab designed in the national structural analysis software with orthogonal and non-orthogonal axis that are commonly encountered in Antalya were selected in central districts of Antalya. The project of these buildings is provided and remodeled in ETABS, and several impacts on static and dynamic analysis are investigated and compared according to TBEC-2018 and TEC-2007. Equivalent lateral force (ELF) and response spectrum analysis (RSA) which are types of linear elastic analysis methods are employed. Besides, according to TBEC-2018, regarding the existing data collected, the performance of existing buildings analyzed by using nonlinear static single-mode pushover analysis in ETABS was evaluated. KEYWORDS: Structural Analysis Using ETABS, Hollow Block Slabs, Structural Analysis Softwares, Nonlinear Pushover Analysis, Seismic Performance, Stiffness Effect on the Seismic Response