China
Africa
Explore chapters and articles related to this topic
Twenty years monitoring of a high strength concrete cantilever bridge
Published in Nigel Powers, Dan M. Frangopol, Riadh Al-Mahaidi, Colin Caprani, Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges, 2018
E.O.L. Lantsoght, C. van der Veen, H. van der Ham, A. de Boer
To find the net deflection at midspan, without the effect of the settlements at the support, the effect of all support settlements should be taken into account. A large settlement occurs at support 1; the measured value of this settlement is -22.3 mm in 2016. Such a settlement would result in a hogging at midspan of the main span between supports 2 and 3. To find the hogging or sagging deflection at midspan of the main span, a beam model is used of the box girder modeled as a girder with a variable moment of inertia I.
Structures: shear force and bending moment diagrams
Published in Ash Ahmed, John Sturges, Materials Science in Construction: An Introduction, 2014
We have just learned how to calculate the bending moment and shear force at any given point in a beam. However, we are normally more interested in the variation of bending moment and shear force along the length of a beam. After all, as engineers we are most interested in the values of maximum bending moments and shear forces in a beam, the positions at which these occur and whether they are associated with hogging or sagging in the beam at these positions. This information would enable us to design a beam in a given material (e.g. timber, steel, reinforced concrete) that is capable of resisting these maximum bending or shear effects.
Analysis of calculation method of hull girder residual strength for cruise ship
Published in Pentti Kujala, Liangliang Lu, Marine Design XIII, 2018
Based on the analysis of NFEM results (see Figure 5) and the failure sequences, the following conclusions could be made: The “simplified whole model” could be applied in the ultimate and residual capacity prediction and a reliable result could be obtained.The superstructures of cruise ships have important influence to the ultimate strength and the upmost deck would buckle first than other structures, which indicates that the superstructure contributes much effort to the ultimate strength. However, the longitudinal stress on the main deck is low and the buckling mode rarely happens.In hogging condition, bottom structures buckle first. Nevertheless, for this ship, the longitudinal plate buckles first than inner bottom plate since the thickness of longitudinal bulkhead plate is much lower.The assumption of extent of collision in 2.2 has little influence to the failure sequences while only reduces the hull capacity a little both in hogging and sagging conditions.The grounding damage assumed in this paper changes the failure modes under hogging condition, and reduces the ultimate capacity by 21%. From this opinion, the assessment of cruise ship residual strength should be focused on the grounding condition.
Study of hull girder ultimate strength at elevated temperatures
Published in Ships and Offshore Structures, 2021
Stamatios Fanourgakis, Manolis Samuelides
The examined ship consists of two steel types, mild steel grade ‘A’ with yield stress of 235MPa and high tensile steel grade ‘AH’ with yield stress of 315MPa. Young’s modulus was assumed equal to 210GPa and the Possion’s ratio equal to 0.3. High tensile steel was applied only to the longitudinal bulkhead and the stools’ (upper, lower) panels and longitudinal stiffeners. For mesh generation S4R elements were used with mesh size equal to 120 × 120mm. Hogging and sagging conditions were examined with applied initial geometric imperfections at the bottom and deck areas of hull girder, respectively. Boundary conditions were applied in two reference points at model’s fore and aft. The reference points were located at the centroid of the hull section, rigid body was constrained with the section nodes. Imposed boundary and loading conditions of the examined states are presented in Table 5. Greater deformation (rotation) was applied in the case of elevated temperature. This is due to the fact that the maximum material’s strength is obtained at greater strain values with the increasing temperature (Figure 3). All parameters have been chosen based on computational cost and time minimisation and keeping results’ accuracy and consistency (Cai et al. 2017).
Ultimate strength characteristics of as-built ultra-large containership hull structures under combined vertical bending and torsion
Published in Ships and Offshore Structures, 2020
Figure 12 presents the ALPS/HULL3D model for the 9300 TEU containership hull using 1556 ISFEM plate elements. Figure 13 shows the progressive collapse behaviour of the hull structure under pure vertical bending moments in hogging or sagging. The first failure moments associated with local buckling or yielding are also investigated. It is found that the first failure of the hull by yielding occurs at the deck panels in hogging at a vertical bending moment of 16.13 GNm. The hull reaches the ultimate limit state, at a vertical bending moment of 17.89 GNm after buckling collapse of the outer bottom panels took place. In sagging, buckling collapse first occurs on the deck panels at a vertical bending moment of 15.21 GNm, and the ultimate limit state, is reached at a vertical bending moment of 15.40 GNm even before the bottom panels yield.
Building response to tunnelling- and excavation-induced ground movements: using transfer functions to review the limiting tensile strain method
Published in Structure and Infrastructure Engineering, 2018
Korhan Deniz Dalgic, Max A. N. Hendriks, Alper Ilki
The model of the fictitious deep beam which is assumed to be representative of real structures is given in Figure 3. The midpoint deflection (Δ) is considered to occur in either the hogging or sagging ground settlement zone. L denotes the length of the beam (in reality, it may correspond to the deflected or entire length of the structure), and H is the height of the beam. In reality, H corresponds to the building height from the foundation level up to the eaves. The roof is not included in the calculations. The fictitious deep beam is elastic, isotropic and simply supported. Soil–structure interaction is ignored and only free-field ground settlements are considered.