The effectiveness of simple weirs and the ability of rural farmers to construct durable weirs are still areas of concern in rural areas in Zambia. The objective of this study is to investigate the ...factors contributing to the varying levels of durability of the simple weir structures used for the diversion of river flows. This study was conducted in five districts where 33 simple weirs located in similar geographical zones were analyzed for their longevity. The research delved into catchment and climatic variables, as well as the social and psychological perception of simple weirs. This study conducted interviews with key informants who were familiar with the use of simple weirs in Muchinga Provinces between 26 December 2023 and 15 January 2024 using semi-structured questions. The findings of this study indicated that simple weirs constructed on relatively square-shaped catchments and narrow-shaped catchment areas were less vulnerable to damage and easy to operate and maintain. The study also found that climatic factors such as storm rainfall events had little impact on the operation and maintenance of these weirs in Muchinga province, as most sites are in the rainfall shadow while farmers’ views about the structures varied from site to site. Overall, planning is necessary for implementing small or large irrigation structures.
This research aims to investigate the fresh and mechanical properties of concrete with diatomaceous earth (DE) and polypropylene fiber (PPF). The cement was partially replaced by DE in the ...concentration ranging from 5 to 20% by weight; whereas, PPF was incorporated in concrete mix as in range of 0.05–0.20% by cement weight. Totally, 25 different mix proportions were developed and their fresh properties were examined using slump, density and compacting factor tests. Besides, mechanical properties were evaluated by. Using compressive, split tensile, and flexural strength analysis at the ages of 7th, 14th and 28th days. Furthermore, concrete durability properties were evaluated using water penetration, chloride permeability as well as sorptivity tests, which have been performed at the age of 28th day. The result exhibits that the incorporation of D.E slightly affects the slump value meanwhile PPF decreases the fresh values. Furthermore, the combination of DE and PPF in concrete significantly enhances the mechanical properties compared to the control mix. The mix proportion of 15% DE and 0.15% of PPF exhibited a noticeable influence on mechanical properties as well as durability properties compare to control concrete.
This paper focuses on reviewing publications related to wheel performance tests and simulation of these tests using finite element analysis to evaluate the service life. Publications from the last ...five decades are studied. A brief introduction on the evolution of wheel performance tests and their importance is discussed. Developments related to experiments and finite element analysis performed by considering material and manufacturing aspects are summarized. Performance tests and simulations performed using different methodologies and adapted optimization procedures are presented to provide readers with a quick overview of past and recent trends in the wheel industry. Different statistical approaches to validate the wheel's reliability to withstand the service loads are also discussed.
Air leaks have a considerable impact on the energy load and durability of buildings, particularly in cold climates. In wood construction using cross-laminated timber (CLT), air leaks are most likely ...to be concentrated at the joints between panels and other elements. This study used simulations of heat, air, and moisture transfers through a gap between two CLT panels causing air leakage in winter conditions under a cold climate. A real leakage occurrence was sized to validate the simulations. The aim of this work was to assess the impact on the energy loads and the durability of an air leak, as either infiltration or exfiltration, for different gap widths and relative humidity levels. The results showed that infiltrations had a greater impact on the energy load than exfiltrations but did not pose a threat to the durability, as opposed to exfiltrations. Gap sizes in CLT may vary, but the effect on the energy load was sensitive to the leakage path in the rest of the wall. As expected, a combination of winter exfiltration and a high level of interior relative humidity was particularly detrimental.
Continuous rigid-frame bridges across valleys are often at risk of rockfalls caused by heavy rainfalls, earthquakes, and debris flow in a mountainous environment. Hollow thin-walled bridge piers ...(HTWBP) in valleys are exposed to the threat of impact from accidental rockfalls. In the current research, ANSYS/LS-DYNA is used to establish a high-precision rockfall-HTWBP model. The rockfall-HTWBP model is verified against a scaled impact test performed in previously published research. A mesh independence test is also performed to obtain an appropriate mesh size. Based on the rockfall-HTWBP model, the impact force, damage, and dynamic response characteristics of HTWBP under a rockfall impact are studied. In addition, a damage assessment criterion is proposed, based on the response surface model, combined with the central composite design method and Box–Behnken design method. The main conclusions are as follows: (1) the impact force of the rockfall has a substantial impulse characteristic, and the duration of the impulse load is approximately 0.01 s. (2) The impacted surface of the pier is dominated by the final elliptic damage, with conical and strip damage areas as the symmetry axis. The cross-sectional damage mode is from compression failure in the impact area and shear failure at the corner. (3) The maximum displacement occurs in the middle height of the pier. The maximum displacement increases with impact height, impact velocity, and rockfall diameter and decreases with the uniaxial compressive strength of the concrete. (4) The initial impact velocity and diameter of the rockfall are the most significant parameters affecting the damage indices. In addition, a damage assessment method, with a damage zoning diagram based on the response surface method, is established for the fast assessment of the damage level of impacted HTWBP.
In this paper a system of the Rędziński bridge will be described. The Rędziński bridge is the biggest object along the A8 motorway around the city of Wrocław and the biggest concrete cable-stayed ...bridge in Poland. For the purposes of the bridge monitoring a system of 222 sensors was installed. Results from the first 5 years of work of the SHM will be presented below.
This paper performs the durability assessment of concrete structures during construction phase in the ongoing large-scale Hong Kong-Zhuhai-Macau (HZM) project with a service life of 120 years. The ...background of this project is first introduced and the durability design at preliminary study phase is recalled. Then, the durability model for assessment is established for HZM and the statistical properties of the model parameters are given. From the collected data on the chloride diffusion coefficients and concrete cover thickness, the statistical properties of these parameters are updated. With the design options adopted in design phase and the updated parameter properties, the achieved reliability levels are calculated for structural elements under different exposure conditions for both normal and accidental working cases. On the basis of the achieved reliability level of durability, a preliminary maintenance planning is performed for the RC/PC elements in the concrete structures, and the corresponding recommendations are given.
This study aims to analyze the engineering properties and durability of binary blended concrete incorporating pulverized coal combustion ash (PCC ash) produced in local areas and assesses the ...sustainability. For this, tests and evaluations were carried out under conditions in which the unit binder weight and unit water weight were fixed at 330 and 175 kg/m3, respectively, while the replacement ratio of PCC ash increased from 0% to 70% at 10% intervals. The results showed that the replacement ratio of PCC ash should be less than 38.9% in order to secure the target compressive strength (fck = 24 MPa) at the age of 28 days in field application. The durability test found that as the replacement ratio of PCC ash increased, the carbonation depth and relative dynamic elastic modulus increased, while the chloride penetration depth decreased. However, the weight–loss ratio remained similar. It was also found that the optimum PCC ash replacement ratio, which satisfies four durability parameters and can ensure the target compressive strength (fck = 24 MPa) in the case of mix proportion conditions set in this study, ranges from 20.0% to 38.9%. The sustainability assessment results showed that as the replacement ratio of PCC ash increased, the global warming potential (GWP), ozone layer depletion potential (ODP), acidification potential (AP), eutrophication potential (EP), photochemical ozone creation potential (POCP) and abiotic depletion potential (ADP) decreased. Therefore, it was proven that the replacement of PCC ash instead of ordinary Portland cement (OPC) under the same concrete mix proportions is effective at reducing environmental impacts.
The durability design of reinforced concrete (RC) structures that are exposed to aggressive environmental attacks (e.g., corrosion due to chloride ingress in marine environment) plays a vital role in ...ensuring the structural serviceability within a reference period of interest. Existing approaches for the durability design and assessment of RC structures have, for the most part, not considered the spatial distribution of corrosion-related structural properties. In this paper, a closed-form approach is developed for durability assessment of RC structures, where the structural dimension, spatial variability, and correlation of structural properties such as the concrete cover thickness and the chloride diffusion coefficient are taken into account. The corrosion and crack initiations of an emerged tube tunnel segment that was used in the Hong Kong-Zhuhai-Macau bridge project were assessed to demonstrate the applicability of the proposed approach. The accuracy of the method was verified through a comparison with Monte Carlo simulation results based on two-dimensional random field modeling. The proposed method can be used to efficiently assess the durability performance of RC structures in the marine environment and has the potential to become an efficient tool to guide the durability design of RC structures subjected to corrosion.
Conducted research is focused on the validation of numerical results of in-house finite element analysis of chloride ion concentration at reinforced concrete bridge deck with cracks and epoxy-coating ...reinforcement protection. The steel reinforcement corrosion is caused by penetration of chloride ions. The chloride ingress analysis is conducted with a special description of the effect of cracks in the directly exposed bridge deck. The diffusion coefficient of concrete in the crack is changed in order to simulate faster penetration of aggressive agents through cracks. The model focuses on the estimation of chloride ion concentration and corrosion initiation in particular locations of the embedded reinforcing steel bars or damaged areas of epoxy-coated bars. The paper deals with evaluation of the chloride concentration with respect to the time to corrosion initiation. The results obtained by in house model are compared with the analytical formula as well as with the commercial software ANSYS.
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