Papers by Keyword: Structural Engineering

Abstract: This study introduces a novel methodology to determine the effective area of artificial tree camouflaged telecommunication towers, focusing on the pine tree type, using drone technology and photogrammetry. Accurate frontal area determination is essential for wind load calculations, critical to the structural design of such towers. Conducted on a telecommunication tower in East London, South Africa, the research applied image thresholding to point clouds generated from drone-captured images. The drone-derived frontal area of 23.484 m², when combined with a force coefficient of 0.5 from previous wind tunnel research, resulted in an effective area of 11.742 m², differing by less than 4% from the in-situ strain-derived effective area of 12.10 m² utilized as verification. The study addresses the lack of guidelines for designing camouflaged towers and highlights the advantages of drone technology over traditional methods. The results suggest a 47% reduction in the original design's effective area, leading to a 20% reduction in bending moments at the telecommunication tower base. This can result in cost savings by reducing the required structural capacity in future designs or increasing antenna space, which is crucial for 5G deployment. The research offers a practical solution to optimize existing telecommunication towers' capacity, improving efficiency without requiring new infrastructure.

Abstract: Conducting surveys of multi-storey buildings is a laborious task, because large volumes of visual and instrumental research should be carried out. Reduction of labor costs with an increase in the reliability of information about the state of damage and technical condition is an actual scientific and practical task. One of the ways to solve it is to use non-destructive vibration diagnostic methods. The purpose of carrying out diagnostics with the use of vibration based damage detection methods is to search for damages in structural elements that can cause the deviation of the dynamic parameters of a structure from calculated ones. Determination of the dynamic parameters of the structure, in particular natural frequencies and mode shapes of mechanical systems, is one of the most important tasks that allows obtaining integral information about the state of a structure. This article presents the results of calculations for the localization of slabs defects in a multi-storey building with a transverse crack, span L = 4.5 (m), height H = 0.2 (m), with prestressed reinforcement d = 0.05 (m). Vibration based Damage Index method was used to localize the defect. During the study, reliable localization values of the defect area of the slab were obtained, this indicates that the vibration method for determining the damage index with a sufficient degree of accuracy allowed predicting the site of damage to the structure.

Abstract: Timber structure seismic analysis is an important problem in structure design and safety of building. In this paper, full-size pseudo-static tests of two single-storey and single bay timber frame with and without infilled wall were carried out. Failure process, failure form and deformation capacity were investigated. The test results indicate that the timber frame has better capability of dissipation of seismic energy. The infilled wall can increase the seismic ability of the whole timber frame structure. There is a good collaborative mechanism between the infilled wall and frame under some construction measures.

Abstract: At the present stage, no detailed specifications and codes about wind effects on low-rise buildings in rural areas were made in Chinese. In order to reduce casualties and property loss due to wind damage, the investigation of wind tunnel experiments were carried out. The results indicate that the influence of purlin and front and rear eaves on wind load should be considered in building design. Because a specific blowing angle of wind would produce the largest wind load in the surface of the house. In the structure design, the value of shape coefficient should be increased to a certain degree and also amplify according to windward and leeward roofs.

Abstract: The basic mechanical properties of the insulation board in external thermal insulation system are studied in this paper. According to the structure of the board, the relevant tests are designed, which includ the plate bearing capacity, the bond strength, the compressive strength and the flexural strength. The test results show that the security performance of the composite insulation board is high and bonding strength is good, compressive strength is high in the case of meeting the basic technical requirements. Besides, with the increase of the insulation board’s thickness, its flexural strength would increase.What’s more, due to the mesh effect on internal reinforcement, failure process has a certain ductility.

Abstract: The influence of insulation firewall on structure stiffness and the mechanical property of firewall in plane have been more mature in the academic research, but its out-of-plane mechanics is not complete at home and abroad. In this paper, static loading test of aerated concrete block filler wall was designed. Through the cracking loads, ultimate loads, failure loads and load-displacement curve of six walls, we make judgment of the impact on infill wall out-of-plane properties and failure morphology. The results indicate that the mainly failure pattern is horizontal crack and diagonal crack, the destroy position is concerned with the strength of four boundary constraints and the load capacity of infill walls can improve greatly after cracking, the height-thickness ratio is the decisive factor.

Abstract: In this review different aspects of material and structural engineering of metal oxides aimed for application in conductometric gas sensors (chemiresistors) were analyzed. Results, mainly obtained for SnO₂ and In₂O₃–based sensors during surface functionalizing by noble metals have been used for showing an opportunity of material and structural engineering of metal oxides to optimize gas sensing characteristics.

Abstract: Modal identification technique is an effective measure of health diagnosis, structural rehabilitation, retrofitting and strengthening or optimization design of structures and materials in structural engineering field. The modal identification theories of random decrement technique and time-series method under ambient excitation are presented in this paper. The two methods are combined to become a joint algorithm for identifying modal parameters effectively. The numerical simulations of a three-layer architecture are carried out to verify the feasibility and practicability of the joint algorithm.

Abstract: Natural excitation technique has found an increasingly wide utilization in civil engineering field. Modal parameter identification in time domain method can identify the structural parameters in the use of impulse response data as input data. The theory of NExT method is presented. By constructing a numerical simulation example under white-noise excitation, and calculating the data by NExT method, the modal parameters can be identified according to complex exponential method and time series-method in time domain. The results and analysis indicate the validity of the method and provide a reference for engineering practice.

Abstract: Modal parameter identification of civil engineering structures under seismic excitations has important implications for health diagnosis, plastic analysis and optimization design of structure. A numerical simulation model of frame construction was carried out. Apply two types of seismic waves on the structure. The seismic excitations are Kobe wave and Shanghai wave which are both generated by actual earthquake records. According to the acceleration response of the layers, the first three order modal parameters can be identified by using complex exponential method. Compared the results with theoretical values, and analyzed the accuracy, the method was considered to have an effective application.