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Two 10-storey benchmark buildings exposed to different earthquakes are considered in the study in order to analyse the performance and capability of the design of the Tuned Mass Damper (TMD) with the optimal properties. Two optimisation algorithms, i.e. the Modified Genetic Algorithm (MGA) and the Grey Wolves Optimization (GWO) method, are used in the investigation. Firstly, the effectiveness of MGA and GWO, under optimally designed TMD system is verified by comparing the results with the ones obtained by other methods. In a second part, the optimum design of TMD system is determined by including mass of TMD as a design variable so as to assess the feasibility of MGA and GWO. The MGA and GWO methods hold the better responses based on the reduction in the displacement, drift and acceleration of all stories subjected to different seismic excitations. The smaller properties of the TMD are attained using the methods of MGA and GWO as compared to the ones obtained by the Den Hartog and Warburton methods based on the objective function. Therefore, the MGA and GWO approaches lead to more practical and efficient solutions, which allows us to design economically the TMD systems rather than that of the other methods based on the reduction of structural responses. The results show that the efficiency of the parameters and modifications can be enhanced by selecting the proper access in the regulation output with requirements to be diminished.

Metal roof panels are commonly used on residential and commercial buildings. Steel panels exposed to hail have not yet been adequately tested for dent resistance. A finite element model (FEM) was used to analyze the entire test setup. To compare artificial hailstones with natural hailstones, which remained intact after impact, different steel sheets were struck by different sizes of artificial hailstones at different terminal velocities. The simulation and the material properties are assessed by comparing the experimental results with the FE model. An equation to predict the dent depth based on kinetic energy and stress is also presented. The results of this study provide a better understanding of the failure modes of hail and roof panels and their effects on dent resistance. In this study, the results of observations and numerical simulations agreed well with those of analytical models. The result is that the proposed equation overestimates the dent depths compared to the dent depths obtained with finite element models, while the equation leads to an underestimation of the dent depths found in the steel sheets.

Hailstones are, by definition, particles of water that fall into the Earth in a frozen solid. Its dimensions can be up to 20 cm. These hard masses strike the Earth at speeds of 80 to 110 km/h, but they do not break despite this collision. The damage caused by hail at this mass and speed is a great deal. For example, a hailstorm in August 2019 in Alicante, Spain, caused 3 million euros worth of damage. The damage they do to car bodywork, aircraft bodies, roofs of houses, solar panels, and wind turbines causes millions of Turkish liras of losses each year. In spite of all this, the studies related to hail cannot be said to have achieved full success due to the inability to simulate hailstones and therefore the damage caused by hailstones can not be fully simulated.In this study, artificial hailstones are made with liquid nitrogen and water, which have not been done before and have not been passed to the literature. It was determined that applications such as steel balls, indentors, normal ice spheres used in hail damage tests did not produce real results and did not show hail characteristics. This deficiency has been eliminated by the proof that the “artificial hailstones” we have made is very close to reality. This proof is confirmed as a result of not breaking the hailstones, giving similar results in firing tests, and parameters such as the density of the artificial hailstones being close to the actual hailstones., Dolu, tanım olarak, donmuş katı bir şekilde yeryüzüne düşen su parçacıklarıdır. Boyutları 20 cm’ye kadar çıkabilmektedir. Bu sert kütleler yeryüzüne 80 ile 110 km/s lik hızlarla çarpmakta, ancak bu çarpışmaya rağmen kırılmamaktadırlar. Doluların bu kütle ve hızlarda verdikleri zarar ise bir hayli fazladır. Örneğin; İspanya’nın Alicante şehrinde 2019’un Ağustos ayında gerçekleşen dolu fırtınası 3 milyon euro değerinde zarar vermiştir. Araba kaportalarına, uçak gövdelerine, evlerin çatılarına, solar panellere, rüzgâr türbinlerine verdikleri zarar her yıl milyonlarca lira kayba neden olmaktadır. Tüm bunlara rağmen dolu ile ilgili çalışmalar, dolunun simüle edilememesi ve dolayısıyla dolunun verdiği hasarın da tam olarak simüle edilememesinden dolayı tam başarıya ulaştığı söylenememektedir. Bu çalışmada daha önceden yapılmamış ve literatüre geçmemiş olan sıvı nitrojen ve su ile suni dolu yapılmaktadır. Daha önceden dolu hasar testlerinde kullanılan çelik toplar, indentörler, normal buz küreleri gibi uygulamaların gerçeğe yakın sonuçlar vermediği ve dolu karakteristiği gösteremediği saptanmıştır. Bu eksiklik, yaptığımız “suni dolunun” gerçekle çok yakın karakterde olduğunun ispatı ile giderilmiştir. İşbu ispat dolunun kırılmaması, atış testlerinde benzer sonuçlar vermesi, suni dolunun yoğunluğu gibi parametrelerin gerçek doluya yakın olması sonucunda pekiştirilmiştir.

Purpose The preliminary layout design of structures impacts upon the entire design process and, consequently, the total cost. The purpose of this paper is to select the most economical layouts that satisfy structural and architectural requirements, while considering the reciprocal effects of cost factors and layout variables at the preliminary stages of design. Design/methodology/approach This paper presents an automated method for cost optimization of geometric layout design of multi-span reinforced concrete (RC) beams subjected to dynamic loading by using the charged system search (CSS) algorithm. First, a novel cost optimization approach for geometric layout problems is introduced, in which both cost parameters and dynamic responses are considered in the preliminary layout design of beams. The proposed structural optimization problem with constraints on the static and dynamic equilibrium, architectural dimensions and structural action effects is solved using the CSS algorithm. Findings The proposed CSS algorithm for solving the cost optimization problem can be easily used for optimizing the span lengths and is also capable of working with various cost functions. The presented examples show that the proposed algorithm using the new cost optimization function provides satisfactory results and can result in over 7 per cent cost saving. Originality/value This is an original paper proposing a novel methodology for preliminary layout design of concrete beams.

Hailstorms cause significant economic losses every year all over the world. Roofs and many other exposed installations can be affected by the impact of hailstones. However, steel resistance to hail impact has not been sufficiently investigated. Predicting the result of hailstone impact is difficult. This can result in significant permanent deformation of the roof. This study aims to develop plastic deformation prediction models for plate structures investigating the plausibility of an equation predicting the dent depth as a function of kinetic energy and yield strength while also addressing the shortcomings of its testing scheme. Causes, results, and solutions to be implemented in the future are also addressed in this work. The proposed equation aims to provide an approximate value for the ratio of dent diameter to dent depth as an input to simplify the solution for the dent depth. For this goal, a new method of making artificial hailstones has been successfully conducted based on the characteristics of natural hailstones. The outcomes of the empirical model were further validated using experimental observations in this study. It was found that within the range of steel sheets tested, the theory gave accurate estimates of the dent depth before the impact. The proposed equation provides insights into the effect of hail impacts on roofs and enables the use of new design methods for the hail resistance of steel sheeting.

Hailstorms pose significant risk for exposed building cladding materials. Steel sheeting is the most important cladding material used. The understanding of steel sheets behavior under hail impact loading is not sufficient for the manufacturing of hail-resistant sheets. With the purpose-built equipment, artificial hailstones of different sizes were launched to impact at steel sheets of different thicknesses and yield stresses as targets. A theoretical approach for the problem of predicting the dent size due to hailstone impact was developed and compared to the test results. The expressions developed in the theory can predict the dent depth before the impact, assuming the ratio between the dent depth and dent diameter is constant. The expression is not able to predict the depth of dents smaller than 0.75 mm and cannot predict whether the denting will occur or not. All hailstone sizes lead to visible dent on steel sheet of thicknesses 0.35 mm, 0.42 mm, and 0.55 mm. Visible denting was also obtained for the 0.75 mm steel samples with 45 mm and 55 mm hailstones; however, no denting occurred using 40 mm hailstones. It was found that the dent depth was inversely proportional with thickness and yield stress, while the dent diameter was found to be proportional to yield stress. As the yield stress of the steel sheet increased, the dent depth decreased for G300 and G550 steel. The dent diameter however increased as the yield stress increased. When the artificial hailstone shatters on impact, significant energy is lost and less energy is available to cause plastic deformation of the impacted material.

This paper presents direct experimental verifications of the active shear planes in bolted connections, previously identified by the first author for determining the block shear capacity. The laboratory test results were obtained by independent researchers for specimens where the applied loads were resisted by the “block” in shear only. The first set consists of five bolted connection specimens in the webs of wide flange sections where the tensile resistance planes had been sawn off. The second set consists of ten bolted connection specimens each in one leg of an angle section that had fractured completely along the net tensile plane through a block shear failure. Comparisons among the gross, net, and active shear planes against the independent laboratory test results showed that the critical shear planes of bolted connections were best represented by the active shear planes rather than either the gross or the net shear planes. It is also pointed out that full or almost full shear strain hardening was generally achieved at the ultimate limit state of block shear failure of bolted connections in hot-rolled steel plates or sections, irrespective of the connection length. Verification against independent laboratory test results of tee sections bolted at the web reinforces this point.

Dolu fırtınalarının sebep olduğu düşünülen hasarın miktarı deprem ve rüzgar hasarına eşit olabilmektedir. Fakat can kaybı ihtimalinin fazla olmaması sebebiyle ne Avustralya’nın ne Türkiye’nin inşaatla ilgili yönetmeliklerinde dolu yükü için herhangi bir tavsiye bulunmamaktadır. Doluya karşı dayanıklı malzemelerin araştırmasının başını genellikle çeşitli teknik ve profesyonel kurumlar ve sigorta şirketleri çekmektedir. En yaygın dolu hasarı testleri çelik topların ya da indentörlerin kullanıldığı indentasyon testlerine dayanmaktadır. Ana kontrol edilen değişkenin bir çukur açmak için gerekli minimum enerji olduğu. Fakat bunun gibi deneyler ile doğal yollardan oluşan dolu tanesinin çarpışma sırasındaki davranışı arasında herhangi bir ilişki ispatlanamamıştır. Doğal yollardan oluşan dolu taneleri karmaşık bir işlem sonucu gerçekleşir ve dolunun çatı kaplama malzemelerine çarpmasıyla çelik ya da diğer yapay materyallerin çarpması arasında hatırı sayılır farklılıklar gözlemlenmektedir. Bu yüzden, dolu yağmuruna maruz kalan çatı malzemeleri ve araç panellerinin gerçeğe yakın hasar tahmini laboratuvar şartları altında dolu taneleri yerine geçen simülasyonlara dayanır. Fakat, dolu tanelerinin doğal yollardan oluşum sürecinin tekrarını gerçekleştirmek laboratuvar şartları altında neredeyse imkansızdır. Bu yüzden, bu çalışmanın hedefi doğal dolu tanelerinin hasara yol açan karakteristik özelliklerini simüle etmektir. Dolu tanelerinin karmaşık yapısı bazı dolu tanelerinin hem sıkışma hem de gerilim altında diğer dolu tanelerinden daha üstün dayanıklılığa sahip olmasına sebep olmaktadır. Gerilime karşı koyduğu kuvvet sıfıra yakın olduğu için saf buz bile bunun gibi dolu tanelerini temsil edemez. Uyumsuzluğun sebebi dolu tanelerinin yapısında karmaşık bir şekilde birbirine kenetlenmiş halde bulunan buz kristallerinin çarpışmadan sonra dolu tanesinin içinden geçen dinamik dalganın gerilime sebep olan kısmına karşı koyabilmesidir. Bu çalışmada buz toplarının gerilime karşı dayanıklılığını arttırmak için mikrofiberler ve Polivinil Alkol (PVA) eklenmesini incelenecek. Bu çalışma dolu tanesinin çarpmasını test etmek için üretilmiş teçhizatla çeşitli dolu tanelerini çatı kaplama malzemeleri üzerlerine farklı çarpma hızlarında atmak suretiyle çeşitli yapay dolu tanesi üretim metotlarını inceleyecek. Önerilen metotla üretilen dolu taneleri, içerdikleri %12 PVA temelli adhezif maddeleri sayesinde yüksek hızlı çarpışmalardan sonra bile tek parça halinde kalabilmektedir. Ayrıca, üretilen dolu tanesi ile doğal yollardan oluşan dolu tanesinin yoğunluğu, saflığı, ve yüzey sürtünme özelliklerine yakın değerlere sahiptir., Damage associated with hailstorms can be at par with the earthquake and wind damage. However, due to low risk to life, the National Construction Code of Australia does not include design recommendations for Hail load. Primarily, various technical and professional bodies along with insurance companies drive the research into hail resistant materials. The most common hail stone damage tests rely on the indentation tests using steel balls or indenters. The main controlling criteria being the minimum energy required to initiate a dent. However, the correlation between such test schemes and the impact behavior of a natural hailstone is not proven. Natural hailstones usually form through a complicated process and display significant variation to steel or other artificial materials during impact with the roofing panels. Thus, the realistic damage assessment of exposed roofing and automotive panels predicates on the simulation of representative hail stones in the laboratory setting. On the other hand, the natural hail development process is nearly impossible to replicate in the laboratory environments. Therefore, the current study aims to simulate the underlying characteristics of a damage-inducing natural hailstone. The complex formation of hailstones yields some hailstones with superior strength under both compression and tension. Even the pure ice without any impurities does not represent these hailstones as they possess virtually zero tensile strength. The discrepancy is rooted in the complex interlocking of ice crystals found in natural hail stones, which can resist the tensile component of a dynamic wave propagating through the ice balls immediately after impact. The current study investigates the addition of microfibers and PVA to enhance the tensile strength of the ice balls. This study assesses a range of artificial hail production methods by employing a purpose-built dynamic hail impact testing equipment to shoot a range of hailstones on roofing panels at various impact velocities. The proposed method with 12% PolyVinyl Alchohol based adhesive produces hailstones which retain their integrity even after impact at significantly high speed. Moreover, the produced hailstones closely maintain the density, uniformity, and surface friction properties of a natural hailstone.

This paper examines the accuracy of design equations specified in the North American, European, and Australasian codes for cold-formed steel structures in determining the ultimate tilt-bearing capacity of single-shear bolted connections without washers in flat steel sheets. It points out that all the code equations do not properly distinguish the tilt-bearing failure mode from the conventional bearing failure mode. While the latter takes place downstream of the bolt, the former takes place upstream. Unlike the conventional bearing capacity, the tilt-bearing capacity is affected by the width of the connected sheet and does not vary linearly with either the sheet thickness or the bolt diameter. Furthermore, it is not affected by material ductility. Based on the test results of 156 specimens composed of G2 and G450 sheet steels having various dimensional configurations, this paper proposes a design equation that is dimensionally consistent and that is considerably more accurate than all the code equa...

The effectiveness of optimal semi-active dampers for reaching the optimum gains of the response of the adjacent buildings connected by magnetorheological (MR) dampers subjected to seismic motion is examined in this study. One of the challenges is to improve an effective optimal control strategy, utilizing the capabilities of the MR dampers. Hence, a SIMULINK block in MATLAB program was developed to compute the desired control forces at each floor level and to the obtain number of dampers. Linear quadratic regulator (LQR) and linear quadratic Gaussian (LQG) controllers are used for achieving the desired control forces, whilst the desired voltage is synthesized based on clipped voltage law (CVL). The control objective is to diminish both the displacement and acceleration responses. As a result, MR dampers can deliver noteworthy displacement response control that is possible with less voltage for the shorter building.

An optimal design strategy based on genetic algorithms (GA) is proposed for nonlinear hysteretic control devices that prevent pounding damage and achieve the best results in seismic response mitigation of two adjacent structures. An integrated fuzzy controller is used in order to provide the interactive relationships between damper forces and input voltages for MR dampers based on the modified Bouc-Wen model. Furthermore, Linear Quadratic Regulator (LQR) and H 2 /LQG (Linear Quadratic Gaussian) controllers based on clipped voltage law (CVL) are also used to compare the results obtained by fuzzy controller. This study employs the main objectives of the optimal design that are not only to reduce the seismic responses but also to minimize the total cost of the damper system. A set of Pareto optimal solutions is also conducted with the corresponding results obtained from the optimal surface of Pareto solutions in this study. As a result, decreasing the number of dampers does necessarily increase the efficiency of the system. In fact, reducing the number of dampers for the dynamic response of the system can contribute more than increasing the number of dampers.

This study proposes the optimal passive and active damper parameters for achieving the best results in seismic response mitigation of coupled buildings connected to each other by dampers. The optimization to minimize the H2 and H∞ norms in the performance indices is carried out by genetic algorithms (GAs). The final passive and active damper parameters are checked for adjacent buildings connected to each other under El Centro NS 1940 and Kobe NS 1995 excitations. Using real coded GA in H∞ norm, the optimal controller gain is obtained by different combinations of the measurement as the feedback for designing the control force between the buildings. The proposed method is more effective than other metaheuristic methods and more feasible, although the control force increased. The results in the active control system show that the response of adjacent buildings is reduced in an efficient manner.

This study is concerned with the strength limit state of serial bolted connections in structural steel plates. It points out that the ultimate load capacity of a serial bolted connection failing in combined bearing and shear-out cannot be computed as the simple sum of the respective ultimate bearing and ultimate shear-out capacities, which is implicitly permitted in design specifications worldwide. Based on the laboratory test results of 10 hot-rolled steel plate specimens composed of three different grades with nominal thicknesses ranging from 5 to 8 mm, the paper first establishes the ultimate bearing coefficient of a 20-mm bolted connection in a structural steel plate to be 3.5. Coupled with the shear-out equation previously derived, a design equation where the shear-out capacity of the downstream bolt varying quadratically with the end distance is then proposed to determine the combined bearing and shear-out capacity. The proposed equation is demonstrated through verification against independe...

Based on the previous research results of the authors, this paper presents an accurate and consistent equation for determining the ultimate shear-out capacity of a structural steel bolted connection. The equation is verified against independent laboratory test results obtained by other researchers around the world. Comparisons against alternative equations found in the design specifications and literature are also included. The paper explains why certain equations appear to be accurate for particular configurations, but are grossly inaccurate for others. This paper describes the various assumptions embedded in the existing equations, some optimistic and others pessimistic. It shows that the current code equations lead to very significant errors on either side of conservatism, while the proposed equation is consistently accurate for all test specimens known to fail in shear-out. A resistance factor of 0.85 is recommended for the proposed equation in order to achieve a reliability index of 4.0. The ...

This study is concerned with double-shear bolted connections in cold-reduced steel sheets that undergo the pure bearing failure mode of the inside sheet. Compared to the published test results of bolted connections failing in the net section fracture, those involving the bearing failure mode had very wide scatter in the ultimate test loads of specimens having seemingly similar configurations. This technical note presents the laboratory test results of 51 specimens composed of G2 and G450 steel sheets, which have very different ductility properties. One new and significant finding is that the absolute bearing capacity can be considerably higher in the rolling direction of the cold-reduced steel sheet than in the perpendicular direction, even though the tensile strength has the opposite trend. Another result is that material ductility has a much greater effect on the bearing capacity than on the net section tension capacity. It was also found that snug tightening had little effect on the bearing cap...

International audience

This paper presents a method for the adaptation of a wind power plant to the energy market using battery energy storage systems (BESS) to show the feasibility of using fast-response batteries, and to calculate its payback period. The proposed method is also used to investigate the optimum battery size according to the installed capacity of the wind farm based on the price and wind forecast, and arbitrage opportunity so as to maximize the profit of the investor. The profit obtained from the market by the battery storage system is compared to the profit from the feed-in tariff for every kilowatt-hour of electricity the wind farm exports to the grid. In this research work, iterative computational-based optimization algorithm is applied to determine hourly charge/discharge commitment of the battery. A case study is conducted for a real wind power generation station in Turkey whose installed capacity is 15 MW. The simulation results show that the proposed algorithm considerably increases the profit and provides an acceptable payback period.

The seismic response history analysis of multi-storey asymmetric adjacent buildings with soil-structure interaction (SSI) during impact is investigated in this study. The coupled multi-degree of freedom modal differential equations of motion for the two way asymmetric shear buildings are derived and solved using a step by step solution by the fourth-order Runge-Kutta method with impact and without impact. The SSI forces are modelled in the form of the frequencyindependent soil springs and dashpots. A numerical example of two-way asymmetric four-storey adjacent buildings under the variation of the important SSI system parameters such as the large and small SSI effects is investigated under the excitation of the 1940 El Centro Earthquake. This study shows that the lateral torsion response of both buildings is affected when impact takes place with the adjacent buildings. The first three modal response histories of each building are significantly reduced due to the effect of the small SSI. Further, it is also observed that the roof twist of the lighter buildings is decreased for the large SSI effect compared to the small SSI effect. Finally, in increased eccentricities, the impact response of buildings is significantly severe.

Building structures are often built close to each other because of lack of available land in metropolitan cities. In this study, the effectiveness of fluid viscous dampers is investigated in terms of the reduction of displacement, acceleration and shear force responses of adjacent buildings. The specific objectives of this investigation are carried out in three parts namely: (1) to formulate the equations of motion for the two adjacent buildings connected with viscous dampers; (2) to find out the effectiveness of fluid viscous dampers in consideration of the threedimensional vibration mitigation analysis when the dampers are connected at all the floors, using both a response spectrum analysis and a time-history analysis; and (3) to investigate the optimal placement of the fluid viscous dampers instead of placing them at all the floors in order to minimise the cost of the dampers. Results show that by using fluid dampers to connect the adjacent buildings of different fundamental frequencies can effectively reduce earthquake-induced responses of either building if damper properties are appropriately selected. Analysis results of this study show that placing fluid viscous dampers at selected floors will result in a more efficient structural system to mitigate earthquake effects.

Sir, the molecular and biochemical mechanism of the sperm dysfunction and infertility caused by varicocele has not yet been clarified. Mammalian spermatozoa membranes are rich in polyunsaturated fatty acids (PUFAs) and are sensitive to oxygen-induced damage mediated by lipid peroxidation. The proposed mechanism for loss of sperm function upon oxidative stress has been shown to involve excessive generation of reactive oxygen species (ROS) [1]. Lipid peroxidation of sperm membrane is considered to be the key mechanism of ROS-induced sperm damage leading to infertility. Theoretically, cellular damage in the semen is the result of an improper balance between ROS generation and scavenging activities. However, little is known about what happens in the seminal fluid and spermatozoa under the conditions of varicocele. Adequate levels of antioxidant enzymes such as superoxide dismutase (SOD) normally maintain the scavenging potential in seminal fluid [2]. A lot of oxygenated compounds, particularly aldehydes such as malondialdehyde (MDA), are produced during the attack of free radicals on membrane lipoproteins and PUFAs. The purpose of the present study was to evaluate the role of seminal ROS and to examine the role of SOD in men with varicocele. The second objective of this study was to compare the varicocele groups showing normal and abnormal spermiogram pattern. The study group consisted of 13 varicocele patients with abnormal spermiogram pattern (VASP) and 12 varicocele patients with normal spermiogram pattern (VNSP) referred to the Urology Department. All patients in both groups were married and infertile (with their fertile female partner) for at least 12 months, and had not received any previous medical therapy for infertility. At physical examination, all patients had a unilateral varicocele that was detectable by palpation. The control group consisted of 10 healthy men proved to be fertile with a normal semen analysis according to World Health Organization guidelines. The mean ages of the patients were 25.4±8.2 (SD) years for the VASP group, 27.2±10.8 years for the VNSP group, and 23.5±4.2 years for the control group. Semen for analyses was obtained by masturbation after a 48-h period of sexual abstinence. Sperm count and motility parameters were measured. After liquefaction, seminal aliquots were centrifuged at 1,500 x g for 15 min. The MDA level was determined by the method described previously [3]. SOD activity was measured by the method of Sun et al. [4]. The significance of differences was evaluated using Mann-Whitney U test. The results are shown in Table 1. The percentage motility and normal morphology were decreased significantly in the VASP group compared with both VNSP and control groups. Sperm motion characteristics and morphology indicated that the control group had significantly better semen quality than the infertile varicocele group. We have found that the seminal plasma MDA levels and SOD activities were not changed in men with varicocele showing abnormal and normal spermiogram pattern when compared with the control group. Hydrogen peroxide, lipid peroxide, and their degradation products (hydroxy alkenals, MDA, etc.) are highly toxic to