Structural Optimization of Ship Lock Heads during Construction Period considering Concrete Creep

Abstract

Traditional structural optimization is mainly based on the assumption that the materials are elastic, which cannot represent real stress fields in structures. In this study, the genetic algorithm, big bang-big crunch algorithm, and hybrid big bang-big crunch algorithm were employed to optimize the design factors of ship lock heads during concrete construction. The optimization goal was to determine the minimum volume of concrete. The factors considered included the hydration heat, the early-stage creep, and the transient deformation under external loads. In the finite element analysis, three types of boundary conditions were considered. The whole construction process was simulated, and the maximum tensile and compressive stresses, the stability, and the overturning of the lock head were examined. Based on the finite element analysis, to reduce the consumption of memory, a set of implicit recursive equations were used to calculate the thermal creep stress. Thirty-four design variables were distinguished for optimization. A case study on the optimization of a ship lock head was used to demonstrate the optimization process. The optimization results showed that the hybrid big bang-big crunch algorithm was more effective, and some conclusions were derived.

Structural Optimization Design of Ship Lock Heads on Soft Soil considering Time-Varying Effects of the Structure and Foundation

“…In these equations, Δσ n is the stress increment, Δε n is the total strain increment, Δε T n is the thermal strain increment, ω in is the implicit integral operator, [D n ] is the viscoelastic modulus, [Q] is Poisson's ratio matrix, c is the linear expansion coefficient, and ΔT { } is the temperature difference [4].…”

“…and Z pi (i � 1-6). As shown in Figure 3, the design of the second-stage concrete also needs to determine the central angles α qi (i � 1-3), the arc radii R qi (i � 1-2), and the length parameters L qi (i � 1-7) [4]. e corridor layer section is shown in Figure 4.…”

“…Designers save concrete materials by setting up empty boxes in the lock head. According to this method, 34 design variables (x 1 -x 15 , y 1 -y 12 , and z 1 -z 7 ) were distinguished in the x-, y-, and z-directions [4], as displayed in Figure 5.…”

“…According to the previous research [4], three types of constraints should be satisfied, which are formulated as follows:…”

“…Based on the material's elastic assumption, Su et al [3] optimized the lock head volume using the finite element method (FEM) to effectively use the concrete material. Subsequently, considering the impact of concrete creep on the structure during the construction period, Su and Bai [4] optimized the lock head on the rock foundation. Under the lock head's gravity, the soft foundation will experience consolidation settlement.…”