Asansörlerde kabin kılavuz ray konsollarının sismik bölgeler için tasarımı, modellenmesi ve analizi

Abstract

Asansörler yapılarda katlar arası insan ve yük taşımayı sağlayarak günlük hayatı kolaylaştıran transport sistemleridir. Özellikle hastane, okul, kamu binaları gibi yapılarda asansörler insanların yer değiştirmesinde oldukça önemlidir. Ancak deprem gibi doğal afet durumlarında asansörlerin çalışma koşulları bozulur ve asansör kullanılamaz duruma gelir. Deprem anında binanın en sağlam bölümleri asansör kuyuları olmasına rağmen, deprem anında asansörlerin kullanılmamasının nedeni, deprem dalgaları sebebiyle asansörlerin yapısal elemanlarında hasarlar meydana gelmesi ve insanların bu asansörlerde mahsur kalabilmeleridir. Bu yapısal elemanların başında asansör karşı ağırlık raylarını ve kabin raylarını asansör kuyusunun duvarlarına bağlayan ve sabitleyen, rayların dikey doğrultuda bir hat halinde kalmasını sağlayan konsol elemanları gelmektedir. Deprem dalgalarının yükleri sonucunda konsol elemanları hasar görebilmekte ve asansörün karşı ağırlığının ve kabinin raylar üzerinde doğrusal olarak hareket edememesi sonucu asansörler kullanılamamaktadır ve içerisinde insanlar mahsur kalmaktadır. Binalarda kullanılan yolcu asansörlerinde çoğunlukla TSE K 179 – "Asansör rayı bağlama sistemi" standardında da görülen standart konsol tasarımları kullanılmaktadır. Büyük depremler sonrası hasar alan binalar incelendiğinde konsolların, gelen deprem kuvvetlerine dayanamadığı ve hasara uğradığı görülmektedir. Son zamanlarda bu hasarları en aza indirmek için yapılan çalışmalar sonucunda farklı bazı tasarımların ortaya çıkarıldığı görülmektedir. Bunlardan iki tanesi; destekli konsol tasarımı ve kanallı konsol tasarımıdır. Destekli tasarıma bakıldığında konsolun içe kıvrıldığı bölgeye eklenen, genelde 10 mm kalınlığında olan destek parçası bulunan konsollarda, etkiyen kuvvetler sonucu oluşan gerilmelerin daha az olduğu düşünülmektedir. Bu konsolun standart tasarıma çok benzeyen bir yapısı vardır, tek farkı eklenen destek unsurudur. Kanallı tasarım incelendiğinde standart tasarıma nazaran farklı bir yapıda olduğu görülmektedir. Konsolun orta bölgesine eklenen kanal tasarımıyla oluşturulan farklı kenarların, konsola etkiyen kuvvetler sonucu oluşan gerilmelerin standart tasarıma göre oldukça fazla azaldığı iddia edilmektedir. Ancak farklı tasarımların üzerinde oluşan gerilmelerin konsolun hangi bölgelerinde yüksek olacağı ve standart tasarıma göre farklılık gösterebileceği göz önünde bulundurulmalıdır. Bu çalışmada, yukarıda belirtilen ve binalarda kullanılan farklı üç konsol tasarım tipinin gerilme ve deformasyon incelemesi yapılmıştır. Bu sebeple; ASME A17.1, TS EN 81-77, TS EN 81-50, TS EN 1998-1 ve IBC 2018 standartları kullanılmıştır. Belirtilen standartlardan; kılavuz ray üzerinde asansörün normal kullanımından kaynaklanan kuvvetler, deprem kuvvetleri, deprem kuvvetlerinin varsayılan yönleri, toplam kuvvetlerin patenlere dağılımı ve toplam kuvvetlerin neler olduğu elde edilmiştir. Elde edilen veriler sonucunda kuvvetlerin hesaplanması için bazı tasarım varsayımlarında bulunulmuş olup devamında bu verilerle üç farklı konsol tasarımı için modeller oluşturulmuştur. Oluşturulan modeller ANSYS sonlu elemanlar programında standartlardan elde edilen verilerle çalıştırılmış ve sonuçlar alınmıştır. Toplam mesh sayısı her bir simülasyonda ortalama olarak 960000 mesh olarak tespit edilmiştir. Sekiz katlı bir binada toplam 10 kullanıcılı bir asansör olduğu varsayılmıştır. Binanın toplam boyu 25 m olarak alınmıştır. Kılavuz rayların sabitlenmesi için gerekli konsollar arası mesafe belirlenmiş ve toplam 10 adet konsol çifti kullanılmıştır. Kılavuz raylar, standartlarda belirtildiği üzere birbirlerine bağlantı levhaları aracılığı ile bağlanmıştır. Deprem kuvvetleri için AFAD TDTH web uygulaması üzerinden deprem açısından en tehlikeli olarak renklendirilen Bingöl ili civarında seçim yapılmış ve hesaplama değerleri kullanılmış olup bilimsel veriler incelenmiştir. Her bir konsol tasarımı için 10 adet simülasyon olmak üzere en az 30 simülasyon yapılmıştır. Tasarımlarda her simülasyon için farklı bölgelere kuvvetler uygulanmış olup en yüksek gerilme değerleri, gerilme değerlerinin nasıl değiştiği ve deformasyon değerleri incelenmiştir. Sonuç olarak en yüksek gerilme değeri standart tasarımda çıkmış olup dikkat edilmesi gerekenler ve sonuçlar ilerleyen bölümlerde belirtilmiştir. Literatür çalışmasının çoğunluğu internette bulunan bilgiler incelenerek en doğru bilgiler sunulmaya çalışılmıştır. Bölümlere göre deprem bilgileri, gerekli asansör bilgileri, asansörün temel tasarım bilgileri, simülasyon verileri, sonuçlar ve yorumlar sıralanmıştır.

Earthquakes mostly occurs at the boundaries of the tectonic plates which forming the compress and overlap motion on each other. There is a frictional force between the interacting tectonic plates that prevents the movement of the plates, and the plates moves when this frictional force is overcome. Seismic waves are mostly caused by movements of the Earth's tectonic plates. Seismic waves are divided into two as "Body Waves" and "Surface Waves". Body waves are known as P and S Waves, surface waves are known as Rayleigh and Love Waves. P waves are the first earthquake waves to felt when an earthquake occurs. Elevators are transport systems that facilitate daily life by providing people and cargo transportation between floors in buildings. Especially in buildings such as hospitals, schools, public buildings, elevators have an important place in people's displacement. However, in natural disasters such as earthquakes, the working conditions of the elevators are disrupted and the elevator becomes unusable. Although the most robust parts of the building are elevator wells at the time of the earthquake, the reason why elevators are not used during the earthquake is that the structural elements of the elevators are damaged due to earthquake waves and people can be trapped in these elevators. One of the main structural element is bracket elements that connect and fix the elevator counterweight rails and car rails to the walls of the concrete elevator well, ensure that the rails remain in a vertical direction. As a result of the forces caused by earthquake waves, bracket elements can be damaged and elevators cannot be used as a result of the counterweight and the car cannot move linearly on the rails, and people are trapped inside. During the use of the lift, horizontal and vertical forces act on the guide rails due to the cabin and load weights. During an earthquake, horizontal and vertical earthquake forces occurs in addition to the forces acted on during normal use. For the passenger elevators used in the buildings, standard bracket designs, which are also seen in TSE K 179 - "Elevator rail fastening system" standard, are used. When the buildings damaged after the big earthquakes are examined, it is seen that the brackets are unable to withstand the incoming earthquake forces and as a result, they are damaged. It is seen that some different designs have been revealed recently as a result of the efforts to minimize these damages. Two of them are; supported bracket design and ducted bracket design. When looking to the supported bracket design, the support piece, which is added to the area where the console is bent, is generally 10 mm thick, and the result is that stresses caused by the forces acting on the bracket are becomes lesser. This bracket design has a structure very similar to the standard design, the only difference is the added support element. When the ducted bracket design is examined, it is known that it has a different structure compared to the standard design. It is argued that the different edges formed by the ducted design added to the center of the bracket, the stresses caused by the forces acting on the bracket have decreased considerably compared to the standard bracket design. However, it should be taken into consideration that the stresses occurring on different bracket designs may differ according to the standard design in which areas of the bracket will be high stress and deformation. In this study, stress and deformation analysis of three different bracket design types mentioned above and used in buildings were performed. Therefore; ASME A17.1, TS EN 81-77, TS EN 81-50, TS EN 1998-1 and IBC 2018 standards will be used. From the specified standards; The forces resulting from the normal use of the elevator on the guide rail, earthquake forces, the assumed directions of the earthquake forces, the distribution of the total forces to the guide shoes and the total forces were obtained. It is assumed that there is an elevator with a total of 10 users in an eight-storey building. The total length of the building and guide rail total length is taken as 25 m. To fix the guide rails, vertical distance between the brackets was determined as 2500 mm and a total of 10 bracket pairs were used. Guide rails are connected to each other by means of connection plates as specified in the standards. On the colored AFAD (Ministry of Interior – Disaster and Emergency Management Presidency) National Earthquake Map, Bingöl Province is seen as one of the most risky province for earthquake, and scientific data from this maps were used and examined. For the earthquake forces, the AFAD calculation values of Bingöl Province, which is created by using earthquake parameters and new mathematical models, are used. After selection of coefficients and horizontal acceleration data, equations from standards are calculated. For TS EN 81-77 standard, horizontal seismic forces acting on the guide rails are found as 24200 N and for ASME A17.1, it is found as 24450 N. Due to the higher value of ASME A17.1 horizontal earthquake force, it is used for simulating of the earthquake forces on the system by using ANSYS. But for the distribution of earthquake loads to the guide shoes, TS EN 81-77 equations are used with 24450 N. Bracket pairs are coded, from bottom to top during the simulations, and the bottom bracket pair is designated as K-1. The forces applied to a single point are from the bracket pair alignments of K-2, K-3, K-5, K-6, K-8 and K-9, while the forces applied as pairs of guide shoes vertically are K-3, K-5, K-6 and K- 8 brackets are in between the guide shoes. The face of brackets where the brackets are attached to the wall are assumed to be fixed supports. With the results, it is examined whether the selected working system can withstand earthquake forces or not. As a result of the data obtained and selected, some design assumptions were made to calculate the forces, and subsequently, models for three different bracket designs were created with this data. Earthquake forces determined and the situations specified with a program using the Finite Element Method will be applied on the simulation. Created models were run in ANSYS finite element program with the data obtained, then the results were obtained. Total mesh numbers are 960000 meshes and total number of elements are 350000 on average, per simulation. For ANSYS finite element analysis; SOLID186, SOLID187, MASS21, TARGE170, SURF154 and CONTA174 element types are used. Minimum of thirty simulations, ten simulations were made to each bracket design. In the designs, forces were applied to different regions for each simulation, and when the force was applied to different regions, the highest stress values and how the stress values changed were examined. Simulation results of forces applied to the standard bracket designs yielded the highest stress value of 168 MPa. The average stress value of the 10 simulations applied was 152.744 MPa. The highest deformation value was found to be 0.2424 mm. Simulation results of forces applied to the supported bracket designs yielded the highest stress value of 127.38 MPa. The average stress value of the 10 simulations applied was 112.0041 MPa. The highest deformation value was found to be 0.096804 mm. Simulation results of forces applied to the ducted bracket designs, the highest 67.748 MPa stress value was obtained. The average stress value of the 10 simulations applied was 55.2374 MPa. The highest deformation value was found to be 0.014785 mm. When the results of the three bracket designs are examined, it is seen that the ducted bracket design has the lowest values for stress and deformation values and the standard bracket design has the highest stress and deformation values. It was found as a result of the simulations that the stress values of the simulations performed with the parameters and forces selected for this study were below the yield strength of 235 MPa. In ASME A17.1, there are allowable stress as shall not exceed 6 mm deformation and not to permament deformation. For TS EN 81-77, deformation shall not exceed formulation given in standard which is 5 mm for selected designs of this study; these conditions are provided safe for selected parameters and designs for this study because none of the designs are exceed the yield strength of the bracket material. In conclusion, the deformation values are below the maximum allowable deformation value of 6 mm and 5 mm and stress values are below yield strength of 235 MPa for this thesis study. All results can be found in 5th and 6th part as a figures and tables. These results are only valid for selected parameters as mentioned above. Technical drawings of bracket designs and figures of simulation results can be found in appendix part. Most of the literature study has been tried to present the most accurate information by examining the information available on the internet and other sources such as books, standarts, articles. According to the sections, earthquake information, necessary elevator information, basic design information of the elevator, simulation data, results and comments are listed.