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Thunderstorm downbursts can impose critical wind loads on long-span transmission line structural system. Existing research has predominantly focused on stationary downbursts, with limited attention given to the analysis of travelling downbursts influenced by environmental wind and parent cloud motion. This paper utilizes the impinging jet method to simulate a travelling downburst at a small Reynolds number, employing the Delayed Detached Eddy Simulation turbulence model for solving the wall-bounded turbulent flow. The radial wind speed distribution of the travelling downburst is subsequently validated against previous experimental, numerical, and observational data. A comparative study is then conducted to discern the differences in the radial wind speed distribution between stationary and travelling downbursts. Finally, a parametric study investigates the influence of jet inlet speed, environmental wind and parent cloud motion on the maximum radial wind speed distribution of the travelling downburst. The findings reveal a significant disparity in the radial wind speed distribution between stationary and travelling downbursts. Notably, parent cloud motion, environmental wind, or their combined effects can alter the height providing the maximum radial wind speed. This variation has implications for the wind load distribution of travelling downburst across the conductor span of the transmission line structural system. [ABSTRACT FROM AUTHOR]

This paper investigates the flexural behaviour of hybrid reinforced concrete (RC) beams having aramid fibre reinforced concrete (AFRC) in the tension zone and high-strength concrete (HSC) in the compression zone. In two series of experimental investigations, the depth of AFRC layer and the concrete strength in the compression zone were varied. The hybrid beams were tested in series 1 to explore the effects of the depth of AFRC layer on load-carrying capacity and flexural toughness. The effects of compressive strength of the concrete in the top half of the hybrid beams on load-deflection behaviour, failure mode and cracking pattern were studied in series 2. The experimental results reveal that the use of AFRC only in the bottom half of the beam enhanced load-carrying capacity and flexural toughness by 62.44% and 87.66%, respectively, compared to the control specimen with no AFRC. The hybrid beam with AFRC-HSC exhibited 5% higher load-carrying capacities, 45% higher ductility and better cracking behaviour than the conventional RC beam. These enhanced structural performances are beneficial for specific purposes such as structures in marine environment where rebar corrosion is the main concern, or structures under extreme loadings where high ductility is required. [ABSTRACT FROM AUTHOR]

Not counting domestic dwellings, it has been estimated that some tens of thousands of older masonry buildings and structures exist nationally and that many of these are potentially at risk of partial (or worse) collapse from falling or dislodged masonry. This has significant implications for building owners, managers, insurers, the local and national economies, and the urban environment. The problem is caused mainly by the slow deterioration of masonry under atmospheric and other environments and by the corrosion of so-called wall-ties, relatively thin pieces of steel that tie the outer leaf of masonry walls to the inner leaf. The problem is likely to be particularly severe for scenarios such as synoptic windstorms and earthquake events as this causes area-wide damage, and potential wide-spread loss of human life – losses that could be prevented by timely intervention. The present paper deals with the research framework and the methodology being employed in a long-term project to develop tools for cost-effective structural masonry assessment and for risk estimation under structural deterioration conditions. Some early findings with potential immediate practical implications are given. Because the effects of deterioration are long-term, the overall project outcomes will take some years to come to fruition. They will be reported in due course. [ABSTRACT FROM AUTHOR]

This paper is concerned with a novel problem of determining the maximum spanning capacity of an elastic catenary arch under its own weight against in-plane buckling. The arch supports may be fixed or pinned or rotationally restrained. The arch is assumed to have a uniform cross-section throughout its entire length and the arch length is assumed to be inextensible. Additionally, catenary arches with a crown hinge are considered. The specific shape of a family of catenary curves is specified by the height-to-span ratio (or the horizontal force) which is to be determined for maximum buckling capacity of the arch. The Hencky bar-chain model is adopted for the elastic buckling analysis as it avoids the need to formulate the governing equation for buckling and it is also a simple model to understand and for coding. From the maximum in-plane buckling load of the optimal arch solution, the maximum spanning capacity of the arch can then be derived. Presented herein are the maximum spanning capacities, optimal arc length to span ratios and maximum buckling loads of catenary arches with various support and crown conditions. [ABSTRACT FROM AUTHOR]

In this paper, a new model for Buckling Restrained Braced Frames (BRBF) is proposed that Shape Memory Alloy (SMA) is used for the yielding core instead of steel. The seismic behaviour of a framed structure with chevron type buckling restrained braces is investigated and their seismic performance factors, such as permanent displacements, inter story drifts and response modification factors are evaluated. Nonlinear time history analysis and Incremental Dynamic Analysis (IDA) of two models subjected to 11 ground motion records is performed using OpenSees software. In order to evaluate the efficiency of the proposed model, it is compared to a BRB model with a steel core that the length of yielding core is 1 m for each model. Comparing the proposed bracing systems with conventional BRBFs indicates that buckling restrained braced frames equipped with SMA are better in terms of permanent roof displacement and maximum inter-story drift. However, the response modification factor of BRB models with steel core is higher. [ABSTRACT FROM AUTHOR]

Laminated Veneer Lumber (LVL) is a popular product used in the building and construction industry because of its high strength, serviceability, aesthetic characteristics, and cost-effectiveness. However, LVL has traditionally been limited to residential and small light commercial buildings. To expand the use of LVL and reduce the need for steel and reinforced concrete structural members, a comprehensive computational study is conducted to understand the material’s structural performance and find an optimal strengthening ratio. In this paper, a new 3-dimensional Finite Element model was introduced and evaluated to predict the structural behaviour, strength properties, and failure damage modes of LVL timber beams reinforced with a Carbon Fibre Reinforcement Polymer (CFRP) sheet. The model is validated with three experimental tests from the literature, with the reinforced timber model showing a 1.8% error compared to the plain timber model’s 7% error. Additionally, a parametric study is conducted to understand the effects of reinforcement length on the structural behaviour of the reinforced beam, with mathematical equations established to express the relationships. The study found that reinforcing 50% of the beam span generally resulted in the most significant strength improvement. This investigation is made for various strength and serviceability parameters. [ABSTRACT FROM AUTHOR]

An implicit limit state function is predicted with a support vector machine (SVM) for reliability analysis of engineering structures to reduce the number of finite element analyses. The accuracy and predictability of the SVM method are reduced considerably by noise in data. In this paper, density-based spatial clustering of applications with noise (DBSCAN) is applied to reduce the noise in training samples for SVM regression. Then, the SVM model is linked with Monte Carlo simulation (MCS) to find out the reliability of the engineering structures. Four different examples of static and dynamic problems are solved to show acceptability and efficiency of the proposed method. It is observed that the proposed method is suitable for a smaller number of performance function calls. Direct MCS, artificial neural network-based MCS and response surface methods have been used to examine the effectiveness of the algorithm. [ABSTRACT FROM AUTHOR]

The shear behaviour of fibre-reinforced polymer reinforced concrete (FRP-RC) beams without web reinforcement suffers from low strength, low stiffness, more brittleness and wide and quick propagated cracks. Fortunately, the addition of various types of fibres could improve most of these weaknesses. On the other hand, the shear strength prediction of FRP-RC beams with various types of fibres is one of the most complex cases in structural engineering applications. Developing generalised, precise and consistent prediction models are necessary and very limited. This paper investigates the impacts of various types of fibres on shear strength and presents proposing four new prediction models, utilising artificial neural networks and empirical nonlinear regression analysis, and modifying the combination of available models based on a collected database of 49 shear test results of FRP-RC members with various types of fibres. The comparison of the developed models with the available equations from the literature indicates that the developed models yielded excellent performance, great efficiency and a high level of accuracy over all other existing models. Additionally, the parametric study confirmed that all the developed models have great abilities to accurately predict the actual response of each parameter, in spite of its complexity, on the shear strength of FRP-reinforced fibrous concrete beams without stirrups. [ABSTRACT FROM AUTHOR]

In this paper, a nonlinear elasto-plastic analysis method under incremental external loads is presented to determine static pushover curves of 3D frame structures. Geometric nonlinearity is taken into account with stability functions, and the nonlinear behaviour of material is considered by plastic hinge hypothesis. Improved matrices and matrix operations for 3D frame elements are given, and the results obtained from a six-storey 3D frame, which is used as a benchmark example, are given comparatively with the related studies. Furthermore, in order to perform these analyses with the developed algorithms, the upgraded computer program TUNAL is used to present pushover curves of a 2-storey RC building for an assumption on torsional stiffness caused by plastic hinges. It is shown that the proposed methodology and the computer program give accurate and reliable results. [ABSTRACT FROM AUTHOR]

This paper represents a detailed investigation of tall hexagonal buildings in the presence of a similar type of single-interfering buildings and double-interfering buildings. The building models are analysed using CFD in ANSYS CFX module. The k-ε turbulence model is used to carry out the numerical simulations. For two buildings case (single interfering building), the wind incidence angles (WIA) vary from 0° to 90° at an interval of 15° and from 90° to 360° at an interval of 30°. The variable spacing of 200 mm, 300 mm, 500 mm and 800 mm has been kept apart for two building case. For the three building case (double interfering buildings), the orientation of the interfering buildings kept varying from 15° to 90° with a regular interval of 15°. The variable spacing between the principal building and interfering buildings is kept 300 mm and 500 mm apart. The model height for both cases is 500 mm in 1:300 length scale. The variation of interference factors for both pressure and force coefficients are evaluated and graphically represented to investigate the hexagonal building model. The interference Factor is found to be minimum at 90° WIA in each of the faces irrespective of spacing between buildings.   [ABSTRACT FROM AUTHOR]

Because the cement content is inexorably growing, CO2 emissions from the cement industry are becoming unavoidable. The use of rice husk ash (RHA) makes the system environmentally benign. This paper investigates the effect of RHA and manufactured sand (M-Sand) on the axial capacity of circular Concrete Filled Steel Tube (CFST) specimens subjected to axial compression. Thirty-two CFST specimens infilled with self-compacting concrete (SCC) with a replacement of RHA and M-Sand to cement and fine aggregate in 0%, 15%, 20% and 25% proportions are subjected to axial compression. Results show that use of RHA beyond 20% decreased the compressive strength of concrete and eventually decreased the axial capacity of CFST and occurred higher local buckling irrespective of their L/D ratios. Failure modes, strength index, confinement along with steel and concrete contribution on axial capacities of CFST specimens are studied. The axial capacities of the specimens were compared with various design code results such as: American concrete institute, Australian Standards, Chinese code, Eurocode, and Japanese code. Among all the codes, Chinese code overestimated the test results and hence, the axial capacity equation is altered and compared the results with test data along with 278 circular CFST data available from literature and found the results to be accurate. [ABSTRACT FROM AUTHOR]