04936ntm a2200337 i 4500 MY-KuUP 20251231150604.0 t||||fr|||| 000 0 ta 251231t20252025my a|||fr|||| 000 0 eng d THE0010198 (Local) Hardback UMPSA eng UMPSA rda FTKA .S93 2025 r Thesis Nurul Syafiqah Binti Abdul Razak, author. The transient response of stiffened mild steel plates subjected to close-in blast loads / Nurul Syafiqah Binti Abdul Razak Kuantan, Pahang : UMPSA, 2025 © 2025 xi, 97 pages : illustrations (some color) ; 30 cm. + 1-CD ROM. rdacontent text rdamedia unmediated rdacarrier volume rda text file PDF Faculty of Civil Engineering Technology Thesis (Master of Science) -- Universiti Malaysia Pahang Al Sultan – 2025 Include bibliographical reference Due to increasing of blast cases, researchers have been conducting thorough studies to enhance the blast resistance of structures like steel plates. Explosion could occur from various angles but steel plates exposed to oblique blast stresses, especially stiffened steel plates, received little attention. Therefore, this thesis investigates and discusses the behaviour of stiffened mild steel plates subjected to oblique close-in blast loads. This study used numerical analysis based on finite element (FE) method in which the FE models were developed and formulated using Abaqus, an FE software. Half-symmetry 3D FE models were used in this study where the models consist of the target steel plates, clamping frames and bolts that were developed using solid brick elements. The mild steel plates dimensions, which were unstiffened, clamps cross-sections and bolts diameters were obtained from the literature. The behaviour of mild steel plates under compression and tension was modelled using classical plasticity model with the influence of strain rates. The influence of strain rates was modelled using the Cowper-Symonds strain rates constitutive equation. On the other hands, the steel clamping frame and bolts were assumed as linear materials as it was assumed the frames and bolts will not fail under applied actions thus, the influence of strain rates was neglected. The blast loads impacted on the mild steel plates were modelled using a built-in blast load function, The Conventional Weapons Effects Programme (ConWep). The stiffeners were divided into five main groups according to the configuration of stiffeners which are single stiffener (SS), double stiffeners (DS), cross stiffeners (CS), double cross stiffeners (DC) and X-cross stiffeners (XS). The dimensions of the stiffeners were varied into four different depth-breadth ratios which are 0.5, 1.0, 1.5 and 2.0. All the FE models then were rotated into different angles (inclined towards the point of detonation). The study then was extended further with the inclusion of ductile damage constitutive model into the steel plate. With this inclusion, the damage of the plate was assessed further such as the crack or rupture of the steel plates or stiffeners. The study found that for stiffener configurations, the central displacements of the CS and DS plates are the lowest and highest, respectively. Additionally, the stiffeners' placement relative to the point of blast is more important than the number of the stiffeners in determining the plate's strength or resistance. Besides, the investigation reveals that increasing the size or the b/d ratio of the stiffeners could reduce the deformation at the centre of the target plate. This is proven by the stiffener with b/d ratio of 2.0 that shows the lowest displacement which is 36.4 mm. Moreover, it was observed that the maximum deflection of the plate moved towards the upper part that is the nearest to the blast loads as it received a higher impact than the centre of the plate as the angle of orientation increases. From the simulation of stiffened steel plates with ductile damage constitutive equation model, different modes of failure were observed from the FE analysis. The position of CS in relation to the point of the biggest pulse acting on them resulted in increased resistance. The performance of stiffeners was greatly affected by their placement with respect to the point of impact and blast pressure. As conclusion, the configuration, orientation, and the size of stiffeners play an important role in influencing the response of stiffened steel plates. The inclusion of damage model improves the understanding of the failure and damage of stiffened steel plates. Faculty of Civil Engineering Technology Dissertations Universities and colleges Dissertations Theses Dissertations lcc THESIS 0 0 lcc 0 0 10000 10000 2025-12-31 0 FTKA .S93 2025 r Thesis T000003883 2025-12-31 15:06:43 2025-12-31 THESIS 0 0 lcc 0 6 10000 10000 2025-12-31 0 CD13812 T000003884 2025-12-31 15:07:15 2025-12-31 THESIS 103817 103823