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Numerical and Experimental Study on Loading Behavior of Facade Sandwich Panels
Get PDFThis paper focuses on the study of the strength of facade sandwich panels used in building construction. The paper describes the results of experimental and numerical research on the behavior of sandwich panels made of polyisocyanurate core (PIR) and their structural connections when exposed to tensile and compressive loads. In the initial phase of this study, laboratory tests were performed to determine the physical and mechanical characteristics of the material from which the sandwich panels are made. Laboratory tensile and compression tests were performed on small samples of sandwich facade panels. In order to verify the obtained results, they were compared with the numerical analysis performed in the ANSYS software. The numerical model was found to accurately predict the results of the laboratory tests, suggesting that the model can be used to predict the behavior of these panels under different loads in service. The study showed that the foam core sandwich panel exhibits excellent mechanical properties. The results indicate the suitability of foam-based composite structures in the construction industry for various applications, such as roof and wall structures. The findings of this study may help in the development of lightweight and durable construction materials for the industry
Life Assessment of Corroded Wire for Prestressing
Get PDFThe repair of structural elements for the prestressing of reinforced concrete is necessary
when existing prestressing wires are damaged or after a certain period of time. The objective of this
paper is to describe the methodology for the life assessment of corroded prestressing wires, sampled
from prestressed concrete elements after a few decades of use. The aim of the presented research was
to determine the real properties of corroded wire in terms of the evaluation of remaining load capacity
using the Theory of Critical Distances (TCD). The methodology also includes spatial 3D characterization
of corroded surfaces, determination of mechanical properties, and Finite Element Analysis (FEA)
of a model of wire with corrosion pits. The final goal of the presented methodology is to enable more
efficient evaluation of repair range and options for the elements of mechanical prestressing systems
within various structures. The results and conclusions indicate that the developed methodology,
based on the interdisciplinary approach and implementation of state-of-the-art methods, has a high
applicability potential for both static and fatigue fracture prediction in the case of prestressed wires.
The proposed method has a huge potential for simple and fast prediction of the life assessment of
engineering structures, particularly for damaged elements with arbitrary geometry feature
Metodologija pregleda i ocena stanja konstrukcije izložbenih hala Beogradskog sajma
Get PDFBeogradski sajam predstavlja jedno od najuspelijih ostva-renja domaće arhitekture i građevinskog konstrukterstva. Sagrađen je između 1954. i 1957. godine, prema arhitek-tonsko-urbanističkom rešenju Milorada Pantovića i kon-struktivnim rešenjima Branka Žeželja i Milana Krstića, kao moderno oblikovani kompleks sa tri izložbene hale prepoz-natljivih kupola. Hala 1 je najveći objekat kompleksa i zašti-ćena je kao spomenik kulture. Svojim specifičnim rešenjem predstavlja izuzetno konstruktivno ostvarenje, a njena kupola i danas drži Ginisov rekord za ovu vrstu konstrukcije. Insti-tut IMS redovno prati stanje objekata Beogradskog sajma i kroz stručnu podršku obezbeđuje sigurnu i funkcionalnu eks-ploataciju izložbenih hala. U radu su prikazani metodolo-gija i rezultati pregleda i ocene stanja konstrukcije Hale 1 nakon skoro 70 godina upotrebe, uključujući sprovedeno ispitivanje sile prednaprezanja u žicama kablova prstenas-tog nosača kupole Hale 1
Life assessment using the finite element method of high-strength low-alloy steel samples exposed to low-cycle fatigue
Get PDFIn the paper, based on the results of experimental research on the behavior of samples in the form of
round smooth test specimens (STS) made of high strength low alloy steel (HSLA), Nionikral 70 (NN
70), under conditions of low cycle fatigue (LCF), a computational stress analysis was performed
using numerical methods.
Experimental investigations of the behavior of the samples were performed with controlled and fully
reversible deformation ( /2 = const, R = min/ max = 1), according to the ISO 12106:2003 (E)
standard.
For computational analyses, the method of least squares (in the Excel program) and the finite
element method (FEM) (in the SolidWorks program) were used. The behavior of HSLA steel during
low cycle fatigue (LCF) simulation was analyzed in the Cosmos module of the SolidWorks program.
On the basis of the analysis of the results of the stress deformation state and the determination of the
life span through the isolines of the life span and comparison with the results of experimental tests, a
graphic representation is given. Specific load cycles involving the entire round smooth test specimen
ligament for a specific load in a wide range of LCF loads were analyzed.
The analyzes showed the justification of the effort to solve the life assessment of steel subjected to
low cycle fatigue (LCF) numerically. The results of experimental tests and simulation tests also gave
us important data on understanding the LCF behavior of HSLA steel NN 70
Determination of the Salt Distribution in the Lime-Based Mortar Samples Using XRF and SEM-EDX Characterization
No full textAlthough, the salt crystallization is one of the most common causes of the deterioration of lime-based mortars, testing of their resistance to the soluble salt action has not yet been standardized. The problems following the development of the globally accepted testing method are, among others: defining the type of mortar samples, ways of samples’ contamination, the type and the concentration of the salt solutions used, environmental conditions during testing, determination of the damage development and the durability assessment. Another task of the testing method is to explain and connect the processes developing in the materials when they are applied in laboratory and real conditions. In this paper, soluble salt resistance testing of lime mortars on the composite samples is presented. The main focus of the paper is on the determination of the salt distribution in this type of samples after the five wetting and drying cycles. Samples consisted of two lime rendering layers (inner – 1/3 and outer – 1/1), both prepared according to the experiences found in the literature for these types of lime mortars when applied on historical structures, placed on the natural stone bases. They were cured in laboratory conditions for 90 days, before drying and exposing to soluble salts action. Two types of 10% salt solutions were used for the test: sodium-chloride and sodium-sulfate. Salt contamination was performed by capillary action only in the first cycle, while in the other cycles samples were wetted by deionized water. After the finalization of the cycles, the detached pieces of mortar and efflorescence were removed from the samples. One of the samples from both groups were then cut in two halves, from which one was used for X-Ray Fluorescence (XRF) and another for Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM – EDX) characterization. For the XRF analysis samples were divided into four layers, and then crushed and sieved through 0.5 mm sieve before testing. For the SEM-EDX analysis the polished thick cross sections were prepared. The paper presents the results of these two analyses, and discusses the advantages and disadvantages of their application for this purpose. Mineralogical analysis of the samples was performed using XRD analysis. It was shown that XRF analysis provides more precise quantification of the elements within one sample, while SEM-EDX analysis gives possibilities for testing of layers with smaller depth within one cross – section
Analiza nosivosti vertikalno opterećenog šipa za potrebe izgradnje petlje „Merošina 1“ na autoputu E-80 deonica: Niš –Merošina
Get PDFU Srbiji je počela izgradnja autoputa E-80 koji će predstavljati saobraćajno čvorište
zapadnog Balkana i biće deo glavne regionalne transportne mreže jugoistočne Evrope. Njegova
ukupna dužina kroz Srbiju iznosi 77 km, a prva deonica u dužini od 5.5 km je završena i puštena u
saobraćaj krajem jula 2023. god. To je prva od četiri deonice Sektora 1 čija je dužina 32.65 km. U
sklopu petlje „Merošina 1“ izgrađen je nadvožnjak koji je oslonjen na devet stubnih mesta na
međusobnom rastojanju od oko 25 m. Svaki stub je fundiran na šipovima i to sa predloženim
rasporedom od 2 šipa u grupi. U radu su na osnovu izvršenih geotehničkih istraživanja terena,
analizirani rezultati nosivosti vertikalno opterećenog šipa prečnika 1.2 m i dužine šipa od L = 18
m. Analiza je izvršena primenom različitih metoda koristeći rezultate statičke penetracije-CPT,
laboratorijskih ispitivanja tla kao i probnog opterećenja šipa
Fatigue crack growth rate of a low carbon microalloyed steel for elevated temperature application
No full textThe operating temperature influence on the fatigue crack growth parameter, was analyzed by testing the
chromium-molybdenum steel for elevated temperatures application of the new generation additionally alloyed with
vanadium. The paper presents a comparison of the fatigue threshold value Kth and the fatigue crack growth rate
da/dN of the specimens cutting from pipe made of virgin steel, tested at room (RT) and operating (HT) temperature
of 540 C. The influence of the notch and crack initiation location, as well as the test temperature values, have a
decisive effect on the fatigue threshold values Kth of the investigated steel.
The macroscopic and microscopic specimens’ fracture surfaces are also shown. Obtained results of fatigue
crack growth parameter, correspond to the SEM micrographs of fractured surfaces
Experimental Determination of JIC for a HSLA Steel Welded Joint
No full textMost serious weldment failures have catastrophic consequences in terms of damage to other equipment,
loss of production, and risks to worker health and safety. For the above reasons, there is a tendency to find the
line between safety and disaster, and this requires a guarantee of the integrity of the welded structure even if a
crack is present.
The structural and mechanical heterogeneity of a welded joint affects its resistance to cracking in both the
elastic and plastic regions. Therefore, it is important to define the test method and the position of the fatigue
crack. The behavior of an elasto-plastic material, during stable crack growth can be described by the J- a
diagram. As the crack propagates, a point on the curve is defined, which represents the critical value of the Jintegral.
The aim of this experiment is to determine JIC value and the procedure is reflected in the
determination of the R curve, i.e. the J‒a curve, which consists of the value of the J integral for uniform
crack increments a. In this paper, two SEN(B) specimens with the fatigue crack in the parent material (PM)
and weld metal (WM) were tested according to standard ASTM E1820 at room temperature (RT) as well as
three specimens with the fatigue crack in the weld metal (WM) at RT, -20 0C, -30 0C
Doprinos Instituta IMS razvoju građevinskih materijala (kratak istorijat, pregled stanja i pogledi ka budućnosti)
Get PDFInstitut IMS ima lidersku poziciju među multidisciplinar-nim naučno-istraživačkim organizacijama u Srbiji i regionu. Visoko je pozicioniran u oblasti građevinarstva i inženjer-stva. IMS poseduje jedinstveni spoj naučno-istraživačkog rada i saradnje sa privredom kao vrlo važne karike u lancu primenljivosti i održivosti rešenja i rezultata istraživačkog rada. IMS je decenijama simbol znanja u oblasti građevi-narstva i industrije građevinskih materijala, što aktivno nastavlja kroz aktuelne i planirane naučno-istraživačke aktivnosti - razvojna istraživanja, realizaciju u privredi, primenu najnovijih saznanja i savremenih tehnologija