Design problems in structural engineering are often modeled as differential equations. These problems are posed as initial or boundary value problems with several possible variations in structural designs. In this paper, we have derived a mathematical model that represents different structures of beam-columns by varying axial load with or without internal forces including bending rigidity. We have also developed a novel solver, the LeNN-NM algorithm, which consists of weighted Legendre polynomials, and a single path following optimizer, the Nelder–Mead (NM) algorithm. To evaluate the performance of our solver, we have considered three design problems representing beam-columns. The values of performance indicators, MAD, TIC, NSE, and ENSE, are calculated for a hundred simulations. The outcome of our statistical analysis points to the superiority of the LeNN-NM algorithm. Graphical illustrations are presented to further elaborate on our claims.
The main cable curve control of landscape suspension bridge is not only the premise of achieving the ideal completed state, but also the key problem of suspension bridge construction control. By analysing the characteristics of the main cable of anchored double tower landscape suspension bridge, the analytical equations for calculating the main cable curve of suspension bridge are derived by parabolic method and segmented catenary method. Then combined with practical work, the main cable curve was calculation methods by using the two calculation methods. Results show that both the parabolic method and the catenary method can be used for the preliminary design of the main cable curve of the landscape suspension bridge, but the segmented catenary method with repeated revision iteration has higher accuracy.
Purpose
The purpose of this paper is to investigate the explosive performance and explosion damage mechanism of T-beam bridge structure.
Design/methodology/approach
On the basis of the existing specification, two T-beam bridge models were designed and fabricated. Test specimens of different explosive dosage and different blast height were carried out. The mechanical process, failure mode, blast damage model, damage identification mechanism and blast evolution law and quantitative evaluation were taken into account.
Findings
The results revealed that the web plate fracture failure is the key to the unstable failure of the whole T-beam bridge. The explosion failure phenomenon and blast damage evaluation criterion of RC T-beam bridge was divided into five stages: the original cracks stage of concrete material (D = 0 ∼ 0.1), the fractures initiation stage of concrete material (D = 0.1 ∼ 0.3), the stable expansion stage of cracks in concrete material (D = 0.3 ∼ 0.55), the unstable expansion stage of cracks in concrete material (D = 0.55 ∼ 0.8), the explosion fracture of steel bars and the overall instability and damage of the bridge (D = 0.8 ∼ 1.0), which can also be described as basically intact, slight damage, moderate damage, severe damage and collapsed.
Social implications
The research result will provide basis for the antiknock evaluation and damage repair technical specifications of the RC T-beam bridge.
Originality/value
The research results of damage evaluation serve as a basis for damage repair and reinforcement of bridge structures after explosion.
To reveal the dynamic behavior and damage mechanism of unreinforced concrete T-beam bridge under blast loads, three specimens were designed. Dynamic strain, acceleration and acoustic velocity pro- and post-blast of three specimens were measured respectively, and the generation, development process and distribution condition of cracks were investigated. The results indicated that ribbed slab fracture failure was a key to the unstable failure of the whole T-beam bridge specimen. Adding steel fiber evenly to the T-beam bridge deck can change the degree of blast damage from “severe damage” to “moderate damage”, which improves the explosion anti performance of the bridge structures. The damage evaluation results provide the basis for damage repair and reinforcement treatment after explosion.
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