255 research outputs found
Kinerja Seismik Berbagai Konfigurasi Bresing Eksentrik Pada Gedung Struktur Baja Tidak Beraturan
No full textPenggunaan bresing eksentrik (Eccentrically Braced Frame, EBF) pada struktur baja merupakan salah satu alternatif yang cukup efektif karena mempunyai kekuatan, kekakuan awal dan daktilitas yang relatif tinggi. Studi ini bertujuan untuk menganalisis struktur EBF pada gedung baja yang mengalami ketidakberaturan horizontal. Variabel studi berupa sepuluh pemodelan variasi konfigurasi bresing. Model uji diberi beban dorong statik nonlinier dari kondisi elastis sampai kondisi runtuh untuk diperoleh kinerjanya. Semua model struktur berada pada level kinerja Damage Control. Berdasarkan perilaku inelastiknya, struktur A EBF F merupakan struktur terkuat pada arah X dan C EBF F menjadi struktur terkuat pada arah Y. Ditinjau dari kekakuan daktilitas struktur, C EBF F merupakan struktur terkaku dan terdaktail pada arah X maupun Y
Damage interaction analysis of ship collisions
No full textDuring its lifetime, a ship may encounter accidents, such as collision and grounding, for which damage consequences in the forms of loss of human life, pollution of the environment, and economic losses may be substantial. This thesis focuses on the damage analysis of two deformable colliding ships using simplified analytical methods and numerical simulations. In the simplified analytical methods, the ship structure is divided into several basic elements. Typical basic elements include the L‐section (angle), T‐section, Xsection (cruciform), web girder, and shell plating. The resistance of each basic element is evaluated, and all resistances are added to obtain the total response of the entire structure. Numerical simulations using the non‐linear finite element software LSDYNA 971 are conducted to provide virtual experimental data, especially when physical experiments are unavailable. Finite element analysis is also useful in observations of the contribution of each structural part to the total resistance. A new formula to calculate the resistance of shell platings is proposed. Derivation of the formula is based on a kinematically admissible displacement field, which is obtained from observations of the characteristic deformation modes in physical experiments and numerical simulations. The shell plating is subjected to a rigid indenter, whose shape is modelled as an elliptical parabolic surface; the surface is parameterized by the curvatures α and β in the transverse and vertical direction. The elliptical parabolic surface is more suitable for idealizing the actual shape of the striking bow than the existing approach, which models the indenter as a sharp point or with a circular surface. By partitioning the plate girder intersection on a side structure of a ship, the effective width of the cruciform is determined. The contribution of the stiffeners to the resistance of their parent elements is also analysed. New formulae for determining the total resistance of a ship side struck by a rigid bow and a bow that has collided with a rigid wall are proposed. These formulae are utilized in the simplified analysis of a collision between two deformable ships. Numerical simulations of right‐angle collisions between two real ships are performed for several collision scenarios. The finite element model, in which a fine mesh is applied in the vicinity of the collision area, consists of 660,000 elements. Three types of collision behaviour are identified: Collision Type 1—a relatively rigid bow striking a deformable ship side, Collision Type 2—a relatively rigid side colliding with a deformable bow, and Collision Type 3—a case in which both ships deform. A new simplified procedure for analysing a right‐angle ship‐ship collision is proposed. Calculation of the resistance of each ship is based on the proposed formulae; their values are subsequently compared to identify the type of collision that will occur. For Collision Types 1 and 2, in which the resistance of one ship is relatively dominant to the resistance of the other ship, the analysis is simplified to a collision between a rigid structure and a deformable ship. Otherwise, a damage interaction analysis between two deformable ships should be conducted (Collision Type 3). During the collision process, the structural damage may switch between the two ships. Updating curvatures α and β of the bow shape due to the damage of the ships is a unique step in this new procedure. The predicted contact force and the internal energy dissipated during the collision demonstrate good agreement with the reference data provided by the numerical simulations
Damage interaction analysis of ship collisions
No full textDuring its lifetime, a ship may encounter accidents, such as collision and grounding, for which damage consequences in the forms of loss of human life, pollution of the environment, and economic losses may be substantial. This thesis focuses on the damage analysis of two deformable colliding ships using simplified analytical methods and numerical simulations.
In the simplified analytical methods, the ship structure is divided into several basic elements. Typical basic elements include the L‐section (angle), T‐section, Xsection (cruciform), web girder, and shell plating. The resistance of each basic element is evaluated, and all resistances are added to obtain the total response of the entire structure. Numerical simulations using the non‐linear finite element software LSDYNA 971 are conducted to provide virtual experimental data, especially when physical experiments are unavailable. Finite element analysis is also useful in observations of the contribution of each structural part to the total resistance.
A new formula to calculate the resistance of shell platings is proposed. Derivation of the formula is based on a kinematically admissible displacement field, which is obtained from observations of the characteristic deformation modes in physical experiments and numerical simulations. The shell plating is subjected to a rigid indenter, whose shape is modelled as an elliptical parabolic surface; the surface is parameterized by the curvatures α and β in the transverse and vertical direction. The elliptical parabolic surface is more suitable for idealizing the actual shape of the striking bow than the existing approach, which models the indenter as a sharp point or with a circular surface. By partitioning the plate girder intersection on a side structure of a ship, the effective width of the cruciform is determined. The contribution of the stiffeners to the resistance of their parent elements is also analysed. New formulae for determining the total resistance of a ship side struck by a rigid bow and a bow that has collided with a rigid wall are proposed. These formulae are utilized in the simplified analysis of a collision between two deformable ships.
Numerical simulations of right‐angle collisions between two real ships are performed for several collision scenarios. The finite element model, in which a fine mesh is applied in the vicinity of the collision area, consists of 660,000 elements. Three types of collision behaviour are identified: Collision Type 1—a relatively rigid bow striking a deformable ship side, Collision Type 2—a relatively rigid side colliding with a deformable bow, and Collision Type 3—a case in which both ships deform.
A new simplified procedure for analysing a right‐angle ship‐ship collision is proposed. Calculation of the resistance of each ship is based on the proposed formulae; their values are subsequently compared to identify the type of collision that will occur. For Collision Types 1 and 2, in which the resistance of one ship is relatively dominant to the resistance of the other ship, the analysis is simplified to a collision between a rigid structure and a deformable ship. Otherwise, a damage interaction analysis between two deformable ships should be conducted (Collision Type 3). During the collision process, the structural damage may switch between the two ships. Updating curvatures α and β of the bow shape due to the damage of the ships is a unique step in this new procedure. The predicted contact force and the internal energy dissipated during the collision demonstrate good agreement with the reference data provided by the numerical simulations.PhD i marin teknikkPhD in Marine Technolog
Analisis Kelayakan Struktural Jembatan BH.8 pada Jalur Kereta Api antara Stasiun Padang – Stasiun Bukit Putus
No full textLaporan Teknik berupa Analisis Kelayakan Struktural Jembatan BH.8 pada Jalur Kereta Api antara Stasiun Padang – Stasiun Bukit Putus ini merupakan hasil kegiatan keinsinyuran yang dilakukan secara bertahap dengan metodologi yang sistematis. Analisis kelayakan dimulai dengan mengumpulkan data-data teknis yang terkait dengan kondisi jembatan eksisting berupa ukuran, konfigurasi dan material jembatan. Data-data tersebut digunakan untuk analisa struktur jembatan terhadap beban-beban yang bekerja pada struktur sesuai dengan peraturan yang ada, sehingga diperoleh gaya dalam ultimat untuk setiap komponen struktur. Kapasitas penampang dihitung untuk dibandingkan dengan gaya dalam yang diperoleh. Kelayakan struktur jembatan ini secara teknis ditentukan dari nilai-nilai gaya dalam dan kapasitas penampang komponen struktur tersebut. Pada bagian akhir laporan diberikan rekomendasi sesuai dengan status kelayakan struktural jembatan yang dianalisis
Shear strengthening of reinforced concrete beams with near surface mounted steel bars
No full textThis paper reports on an experimental study examining reinforced concrete beams without stirrups strengthened with Near Surface Mounted (NSM) steel bars. The beams were simply supported and were subjected to four point bending load. Three beams tested were designed as control specimens and the other six beams were strengthened with NSM steel bars. Three ratios of longitudinal reinforcement (1%, 1.4%, and 2.4%) and two types of installation angle (45 and 90 degree) were used as test variables. The test results in terms of graphs of deflection due to shear forces are presented to demonstrate the ability of different longitudinal reinforcement ratios and installation angle to withstand shear forces. The influence of the test variables on the crack patterns was also observed. It was found that NSM steel bars increase the shear strength of reinforced concrete beams without stirrups significantly. However, in the case of higher longitudinal reinforcement ratios the beams failed in brittle mode as indicated by a sudden drop in the shear force-deflection graphs
Shear capacity of reinforced concrete beams strengthened with web side bonded CFRP sheets
No full textThe shear capacity of reinforced concrete beams strengthened with web side bonded carbon fiber-reinforced polymer (CFRP) sheets was measured experimentally. Nine reinforced concrete beams without stirrups; three control beams and six beams strengthened with minimal application of web side bonded CFRP sheets, were tested. The test variables were ratio of longitudinal reinforcement (1%, 1.4%, and 2.4%) and angle of application of CFRP sheets (450 and 900). The test results show that reinforced concrete beams strengthened with web side bonded CFRP sheets have higher shear capacity compared to the control beams. Shear capacity of strengthened beams with 450 angle of application of CFRP sheets is similar to that of beams strengthened with 900 angles. Beams with 1% of longitudinal reinforcement ratio failed in flexural mode indicated by concrete crushing in compression zone while beams with higher longitudinal reinforcement ratio (1.4% and 2.4%) failed in brittle mode as indicated by delamination of the concrete cover
On the spatial and temporal coherence of wireless vehicular short range channels
No full textWe consider spatial and temporal coherence of the vehicle–to–vehicle (V2V) wireless communication channel with focus on a suburban residential highway. The dominant reflectors in such an environment are vehicles passing in the adjacent lane and houses
along the road. Instead of treating the reflectors as point targets, the V2V short range propagation environment requires partitioning of the illuminated reflector side into
sufficiently small tiles. The channel transfer function is obtained as a superposition of specular reflections from the tiles, the line–of–sight (LOS) component, and the ground reflection. The tile size is selected to ensure that the ratio of the tile area to the tile–to–receiver distance satisfies the far field conditions. The reflected power is described by the tile radar cross section (RCS). The bistatic physical optics RCS model is adapted to account for the tile’s orientation with respect to the ray geometry. We apply the superposition model to the numerical analysis of two general scenarios
for a 22MHz channel in the 2.4GHz band. The first scenario considers a single vehicle reflector passing in the lane adjacent to the V2V communication pair. Both the vector network analyzer (VNA) experiments and the tiling model analysis illustrate that repositioning of the reflector, the transmitter, or the receiver by a few centimeters results in change of the signal power by several decibels. The second scenario analysis characterizes the channel coherence statistics for the
suburban residential highway. We consider the V2V single lane LOS and non–LOS geometries, where in the latter the receiver is shadowed by a large vehicle. The reflectors are both houses and vehicles passing in the opposite direction. The measure of channel coherence is the normalized spatial covariance calculated by correlating transfer functions corresponding to feasible receiver position pairs and performing spatial smoothing. The area of feasible receiver positions is divided into contiguous squares
whose size ensures wide sense quasi–stationarity within the square. Irrespective of direction the correlation remains high and a typical sedan roof usually does not provide sufficient spacing to obtain average inter–antenna correlation lower than 0.5. The upper bound on coherence time extends over the transmission time of multiple packets for systems in the considered band, and does not allow for usable time diversity.Ph.D.Includes bibliographical referencesIncludes vitaby Haris Krem
Shear strengthening of reinforced concrete beams with near surface mounted steel bars
No full textThis paper reports on an experimental study examining reinforced concrete beams without stirrups strengthened with Near Surface Mounted (NSM) steel bars. The beams were simply supported and were subjected to four point bending load. Three beams tested were designed as control specimens and the other six beams were strengthened with NSM steel bars. Three ratios of longitudinal reinforcement (1%, 1.4%, and 2.4%) and two types of installation angle (45 and 90 degree) were used as test variables. The test results in terms of graphs of deflection due to shear forces are presented to demonstrate the ability of different longitudinal reinforcement ratios and installation angle to withstand shear forces. The influence of the test variables on the crack patterns was also observed. It was found that NSM steel bars increase the shear strength of reinforced concrete beams without stirrups significantly. However, in the case of higher longitudinal reinforcement ratios the beams failed in brittle mode as indicated by a sudden drop in the shear force-deflection graphs
- …
