CLT beam analysis using classical elastic theory of layered beams

The classical elastic theory of layered beams is used for the analysis of cross laminated timber (CLT) beams. A brief introduction of the theory is given and followed by examples. The theory of layered beams offers a widely studied, well established method for the analysis the CLT beams including displacements and stresses of each layer of the beam. It is shown that the theoretical basis of the widely used Shear Analogy is the same as the theoretical basis of the theory of layered beams. The results are compared to test results and to results of the finite element calculations. It is seen that the deflections and strains are in 10 % fractals in mean in the considered cases. The theory of layered beams seems to be suitable method in the analysis of the CLT beams at the elastic phase.

Prediction of Deflection of Reinforced Concrete Beams Considering Shear Effect

This paper proposes a method to evaluate the effect of shear on the deflection of reinforced concrete (RC) beams. The deflection of RC beams due to the effects of flexural and shear cracks shows different results from those obtained from the elastic theory. The effect of shear on deflection was compared and analyzed in this study, on the basis of experimental results and elastic theory using the virtual work method. The shear effect on the deflection of RC beams by elastic theory was extremely small. However, experimental results showed a difference of over 40% from the results predicted by elasticity theory. In this study, a new method was developed to reasonably predict the deflection of flexure-critical RC beams using the deflection incremental coefficient due to shear. The proposed method was compared with the existing experimental results obtained from the literature for verification. As a result of the comparison, the deflection obtained using ACI 318-19 underestimated the actual deflection by approximately 33%, whereas the deflection obtained by the proposed method predicted the experimental results relatively accurately.

Calculation Derivation and Test Verification of Indirect Tensile Strength of Asphalt Pavement Interlayers at Low Temperatures

When the direct tensile test is adopted to determine the interlayer tensile strength of the asphalt pavements, specimen separation or internal cracking often occurs at the bonding area of the loading head, rather than at the interlaminar bonding interface. In view of the tedious and discrete data of the direct tensile test, this paper attempts to introduce an indirect tensile test to determine the interlayer bond strength of asphalt pavement to solve this problem. However, the indirect tensile test method of a binder lacks the corresponding mechanical theory. This paper deduces the calculation formula of the indirect tensile strength of a binder based on elastic theory. A mechanical model of the test was established with the finite element method. In accordance with the two-dimensional elastic theory and the Flamant solution, an analytical solution of tensile stress in the indirect tensile test is proposed through the stress superposition. On this basis, the calculation formula for the indirect tensile strength of the interlaminar bonding is derived according to Tresca’s law. A low-temperature indirect tensile test was designed and conducted to verify the correctness of the formula. By comparing the results of the indirect tensile test and direct tensile test, it is found that the interlaminar strength of the mixture measured by them is similar, and the dispersion of indirect tensile test results is small. The results show that the indirect tensile test can replace the direct tensile test to evaluate the interlaminar tensile strength.

THE BEHAVIOR OF THE SOIL UNDER FOUNDATION OF OFFSHORE GRAVITY STRUCTURES SUBJECTED TO DIFFERENT COMBINATION OF LOADS

This study aims at analyzing the behavioral rules of the soil under the bottom of the offshore gravity structures when it had been subjected to the combination of load types; in which the problem of determining the deformation of the ground in semi-infinite space is determined by the view of deformed solid mechanics and elastic theory. The ground plane displacement of the soil is simulated by the computer when the structural system is subjected to concentrated loads and the distribution load is consist of the eccentricity due to wave load and other horizontal loads.

Phát triển chương trình tính toán kết cấu mặt đường nhựa theo phương pháp phân lớp hữu hạn

Phương pháp phần tử hữu hạn (FE) đã được sử dụng rộng rãi trong việc mô phỏng và dự báo sự xuống cấp của kết cấu mặt đường nhựa. Tuy nhiên, mô hình khối ba chiều (3D) trong các hệ thống phần mềm thương mại như ABAQUS hay phần mềm mã nguồn mở như Cast3M đòi hỏi tài nguyên và thời gian tính toán lớn. Để giải quyết vấn đề này, các mô hình đơn giản hóa được quan tâm phát triển cho các mục tiêu cụ thể. Trong nghiên cứu này, lý thuyết cơ bản về phương pháp phân lớp hữu hạn (Finite Layer Method) được trình bày và là cơ sở phát triển mã nguồn FastKM bằng ngôn ngữ lập trình Python và giao diện người dùng cho phép mô phỏng bài toán kết cấu mặt đường nhựa nhiều lớp. Kết quả nhận được là đồ thị và biểu đồ màu thể hiện chuyển vị, ứng suất, biến dạng của kết cấu. Tiếp đó, một kết cấu mặt đường nhựa điển hình được mô phỏng trên 3 phần mềm là CAST3M, ABAQUS và FastKM theo với 3 phương pháp phân tích khác nhau là LET (Layer Elastic Theory), FEM (Finite Element Method) và phân lớp hữu hạn FLM (Finite Layer Method) nhằm kiểm chứng tính chính xác cũng như so sánh thời gian tính toán giữa các mô hình. Phần mềm FastKM sử dụng phương pháp FLM cho kết quả chính xác tương đương với mô hình phần tử hữu hạn 3D trên Abaqus và thời gian tính toán nhanh hơn hai phương pháp còn lại.