Cam lifleri ile güçlendirilmiş alçı (CLGA) panellerden oluşan yarı-prefabrike yapısal bileşenlerin deneysel incelenmesi
Experimental investigation of semi-prefabricated structural components made of glass fiber reinforced gypsum (GFRG) panels
Yazar: BEYZA KAPUCU GÜZELBULUT
Danışman: PROF. DR. OĞUZ CEM ÇELİK
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Mimarlık Ana Bilim Dalı / Çevre Kontrolü ve Yapı Teknoloji Bilim Dalı
Derece: Yüksek Lisans, 2021
Konu: Deprem Mühendisliği = Earthquake Engineering ; Mimarlık = Architecture ; İnşaat Mühendisliği = Civil Engineering
Dizin: Kompozit malzemeler = Composite materials ; Prefabrike beton bileşenler = Prefabricated concrete component ; Yapı malzemeleri = Building materials

Özet:
Her geçen gün artan nüfus ve çarpık kentleşme, yönetmeliklere uygun yapılmayan binalar, değişen yönetmeliklerle mevcut hali güvenilir olmayan olarak değerlendirilebilecek binalar özellikle Türkiye gibi deprem kuşağında yer alan ülkeler için büyük bir sorun oluşturmaktadır. Daha az maliyetle üretilip daha hızlı inşa edilebilen sistemler bu sorunları çözmek için bir alternatif olurken, mevcut deprem yönetmeliklerine de uyum sağlaması gerekmektedir. Hızlı inşaat tekniklerinden biri olan cam lifi ile güçlendirilmiş alçı (CLGA) paneller, diğer adıyla hızlı duvar (RapidWall) olarak da bilinen paneller, modüler olarak üretilen yarı-prefabrike sistemlerdir. Panellerin modüler olarak üretilmesi yapı sistemine belirli sınırlamalar getirmektedir. Bu sınırlamalar özellikle yapısal ve mimari bakımdan olurken, özellikle sosyal konut olarak tasarlanacak toplu konut projelerinde daha düşük maliyetli, ancak daha yüksek performansa sahip yapılar üretilmesine olanak sağlamaktadır.
CLGA paneller az insan gücü ile hızlı inşa edilebilir olmaları, görece ekonomik olabilmeleri, hafif olmaları ve panel içindeki boşlukların etkili kullanımı ile yeterli süneklik ve dayanımın elde edilmesi, yapımının tamamlanmasından sonra ek bir ince işçiliğe gerek duyulmaması, geleneksel bina yapımına göre enerji ve CO2 emisyonu tasarrufu sağlaması, yangına, sese ve neme karşı dayanıklı olması gibi özellikleri ile başta Avusturalya, Çin ve Hindistan gibi ülkelerde kullanılmaya başlanmıştır. CLGA kullanılarak yapılan yapılar deprem bölgelerinde az katlı, depremin çok görülmediği bölgelerde ise 5~10 kata kadar çıkmıştır. Türkiye'de ise henüz bir tasarım şartnamesi bulunmadığı için CLGA panelleriyle yapılmış bir yapı yoktur. Bu tezde, CLGA panellerin yapısal ve sismik karakterinin anlaşılması için yapılan deneyler, sonuçları ve gözlemleriyle verilmiş, analizler yapılmıştır.
Deneyler temel olarak üç ana başlıkta incelenmiştir: diyagonal basınç deneyi (kayma deneyi), duvar deneyleri ve kiriş deneyi. Bu deneylerde numuneler gerçek ölçekte üretilmiştir. Diyagonal basınç deneyleri ile panellerin doluluk oranları, hangi bölgelerdeki dolguların davranışa ne şekilde etkidiği, dolgu malzemesi olarak yalnızca beton ve betona ek olarak çelik donatı bulunması, kullanılan çelik donatı sayısının başlangıç rijitliği ve kayma karakteristiğine etkisi incelenmiş ve hasar tipleri detaylı bir şekilde açıklanmıştır. Elde edilen verilerle, numunelerin düşey yük-yerdeğiştirme, kayma gerilmesi-kayma şekildeğiştirmesi (τ-γ) diyagramları elde edilmiştir. Tamamı dolu olmadıkça dolgu oranının dayanıma önemli bir etkisinin olmadığı, panellerin en zayıf noktası olan doldurulmamış kısımlarından hasar aldığı, kullanılan donatının yalnızca başlangıç rijitliğini arttırdığı ve dayanıma bir etkisi olmadığı görülmüştür. Bu nedenle, taşıyıcı duvar deneylerine tamamı dolu ve iki uç hücresi dolu ortası boş CLGA panel duvarlarla devam edilmiştir. Çevrimsel yanal yükler altında paneller göçmeye kadar zorlanmıştır. Elde edilen verilerden histeretik yük-göreli öteleme oranı, zarf eğrileri ve kümülatif enerji yutma eğrileri incelenmiştir. İki duvar numunesi karşılaştırılmıştır. Kiriş/döşeme deneyinde ise yalnızca kalıp olarak kullanılan CLGA panellerinin sistem performansına etkisi incelenmiştir. Kiriş/döşeme numunesi TS500'de önerilen kurallara göre tasarlanmıştır. Yapılan deneyler sonucunda CLGA paneliyle hazırlanan kiriş/döşeme numunesi çok sünek bir davranış sergilemiştir. CLGA panelinin kiriş/döşeme sisteminin eğilme dayanımına önemli katkı sağladığı görülmüştür.

Abstract:
Every passing day, with increasing population and unplanned urbanization, buildings designed to older design codes could be considered as unsafe when an evaluation is done using the current/updated structural design codes. This situation has been a big problem especially for countries located on active seismic zones like Turkey. While alternative cost-effective and rapid construction systems are candidate solutions for such problems, it is clear that they should satisfy new seismic requirements mandated by the codes. Glass fiber reinforced gypsum (GFRG) panels, also known as RapidWall, are one of the rapid construction techniques in this area. GRFG panels are manufactured as modules and semi-fabricated products. However, manufacturing of panels as modules brings additional limitations to the structural system of the building. While the limitations are especially in terms of structural and architectural aspects, it allows to build low-cost structures with enhanced performance especially for mass-housing projects to be designed as social housing. 
GRFG panels were promoted to use in several countries such as Australia, China, India etc., due to its rapid construction technique with less man power, relatively cheap prices, tailorable ductility and strength by using their infills effectively, and minimising fine works after construction. Also, saving energy, reducing CO2 emission compared to traditional construction techniques, and fire, noise and humidity resistant properties make them favorable against alternative systems. Until now, low rise buildings have been constructed in seismic zones using GFRG panels. Buildings with 5~10 stories were designed and built in regions with low seismic activity. In Turkey, building with GFRG panels is a new concept and therefore there is no design code available. In this thesis, full scale experiments are performed and presented to better understand structural and seismic characteristics of such systems with GFRG panels.
Experimental part of this thesis is considered in three main categories: diagonal shear tests (monotonic), wall tests (cyclic), and beam/slab test (monotonic). Since the proposed system is new and has not been included in structural codes, it is hard to determine the specimens dimensions, actuator type to be used in testing, and other testing limitations. Also, the effect of infill ratio and alternatives is not well-known yet as there has been limited work so far. Prior to testing, preliminary capacity calculations are done to estimate the load capacities for the diagonal shear tests, wall tests, and floor/beam testing. Diagonal shear tests have been used to better design the wall specimens to be tested under cyclic load reversals. The beam/slab testing has been  conducted to understand/investigate the gravity load behavior/structural performance of the GFRG panels. All specimens were manufactured on a 1:1 scale. 
In the diagonal shear tests, effect of infill rates, infill region, infill material, existence of reinforcement bars, effect of number of reinforcement bars on initial stiffness and shear characteristics as well as failure modes are explained for each specimen in detail. Vertical load-displacement, shear stress-shear strain (τ-γ) graphs are obtained based on the experimental data gathered from the specimens. Unfilled (or void) specimens are considered as Group 1, specimens that only edge cells are filled (with and without rebars) are considered as Group 2, specimens with only middle cell is filled (with and without rebars) are considered as Group 3, all filled/solid (with and without rebars) specimens are considered as Group 4. Failure modes of Group 1 and Group 3 specimens are obtained as crushing around head/edge regions where loading is applied. Group 2 specimens failed mainly due to shear cracks around the unfilled middle cell. Group 4 specimens failed due to seperation (or loss of bond) of concrete blocks from the GFRG mold. It reveals that the infill rate, unless fully filled, has no effect on the strength since panels were damaged at the weakest locations (i.e. in the void cells). Vertical load capacity of Group 4 is approximately 3.5~4 times higher than other groups. Even though Group 2 and Group 3 have concrete fill and added rebars, they did not increase their vertical load capacities. Initial stiffness of Group 4 specimens is higher than other groups around 1.3~3.6 times. It can be said that rebars slightly increases initial stiffness, but does not change vertical load capacity. When it comes to stress capacities of the specimens, Group 1 has the highest stress capacity. Since the section is composed of concrete, gypsum, and steel rebar (i.e. a composite system), the transformed area concept has been used to evaluate the stresses in such components. Transformed area is calculated by summation of transformed areas which are defined as the multiplication of the area and ratio of elastic moduli of materials. When failure types of the digonal shear tests are considered, it is decided to continue to full scale wall experiments with reversed cyclic lateral loading for the cases of completely filled cells and infilled two end cells only (i.e. the middle cells are unfilled). 
Wall panels are cyclically tested to failure. Vertical load is not considered during the wall tests because GFRG panel systems have application potential mostly for the buildings with 2~3 stories (i.e. low-rise buildings). W1 (Wall 1) is the first specimen whose only edge cells are filled. However, all cells of W2 (Wall 2) are filled with concrete with a centrally placed reinforcement bar. In the experiment of Wall 1, diagonal cracks first formed at initial displacement cycles. Then, cracks were combined and longitudinal cracks were formed between the unfilled cells. Also, straingauge data show that yielding deformation is reached in longitudinal rebars around the connection region between the top beam and end column. It can be said that the connection between column and beam is the most critical region for rebars' strains. In the experiment of W2, diagonal cracks were observed. However, desired displacement levels were not achieved due to overall slenderness of the panel. After several cycles, the panel laterally buckled/deformed despite the existing out-of-plane displacement restrainer frames. Therefore, this panel system was loaded using the monotonic loading (pull) protocol instead of cyclic loading protocol. Straingauge data of W2 show that straingauges around the connections between the foundation and columns also between columns and top beam reached yielding deformation. The most critical/stressed region for the rebars are these locations for W2. Hysteretic load-displacement, envelope curves, cumulative energy dissipation curves are obtained for the two wall specimens in a comparative way. W2 had higher initial stiffness in tension and compression. Cumulative dissipated energies of the two specimens are compared under tensile and compressive loads. Note that W1 had higher dissipated energy than W2, mainly from the fact that W2 could not have reached the desired displacement/drift level. Equivalent damping raitos of the specimens were calculated and compared. Equivalent damping ratio of W1 is around 16% initially and drops nearly to 10% with increasing loading cycles. 
As for the performance of beam/slab specimen, the behavior is investigated under vertically increasing mid-span load. Since GFRG panels are considered as a formwork system in general, the impact of such panels on performance is significant. The beam/slab specimen to be used in the experiment was designed as per TS500. The beam/slab system made with GFRG panel showed very ductile behavior. Ductility coefficient is found to be µ=4.53. Large cracks were observed at the end of the experiment. Added glass fibers in the panel are exposed around the cracks, revealing that these fibers experienced significant tensile stresses and thus contributed to the bending capacity. In brief, it was observed that the GFRG panel contributes to bending strength of the beam/slab system significantly. Flexural stiffness of the system is approximately 31% higher than the stiffness of system with the RC micro beams only. In addition, GFRG panels carry 24% of the total moment on the system which is nearly one third of the moment carrying capacity of the RC micro beams.
To conclude, structural and seismic behavior of GFRG panel systems are investigated experimentally. Diagonal shear tests, cyclic wall tests, beam/slab test are conducted. For the wall specimens, the effect of infill rate, ratio of steel rebars, location of the infill, and the effect of GFRG panel on the overall system behavior are analyzed. Results from various specimens are comparatively discussed. It is recognized that such systems could be viable solutions especially for low-rise buildings to be built in Turkey in future. Some changes in the geometric properties are possible to comply with the current local codes.