Search Results (755)

During intense ground motion excitations, the pounding between adjacent buildings may result in extensive structural damage. Despite the provision of regulations regarding the minimum separation gap required to prevent structural collisions, the majority of existing structures are poorly separated. The modern seismic design and assessment of structures are based on the definition of acceptable response levels in relation to the intensity of seismic action, which is usually determined by an acceptable probability of exceedance. From this point of view, the seismic performance of a typical eight-storey reinforced concrete (RC) frame structure is evaluated in terms of pounding. In particular, the performance is evaluated using six different separation gap distances as a fraction of the EC8 minimum distance. As the height of the adjacent structure affected the required separation distance, the examined RC structure was assumed to interact with four idealized rigid structures of one to four storeys. The typical storey height was equal between the examined structures; therefore, collision could occur at the diaphragm level. To this end, incidental dynamic analyses (IDAs) were performed, and the fragility curves for different limit states were obtained for each case. Finally, the seismic fragility was combined with the hazard data to evaluate the seismic performance probabilistically. Full article

Considering the proposed strict new constraints of public authorities, decarbonization has become a key trend in recent years. Although several countries have started the process of decarbonization through the introduction of electric vehicles in their public services, for many countries, especially developing countries, transportation is still a hard sector to decarbonize. The presence of obsolete and polluting vehicles discourages citizens from using public transport and thus incentivizes the use of private vehicles, which create traffic congestion and increase emissions. Based on these considerations, this paper aimed to implement a simulation for a public service in Eritrea, evaluating whether it is possible to take a long trip using an electric minibus. A case study is implemented highlighting the barriers of electrifying transportation in this area, producing results on fuel consumption and service reliability. In the case study, four scenarios are presented to estimate the service. The scenarios evaluate the possibility to perform from three to five recharges. Fewer charges mean longer charging time, leading to a 2 h charging phase in Scenario 1, while recharging more than twice along the route will lead to shorter 30 min charges, as in Scenario 3. The case study also highlights the relevance of the slope in electric vehicle performance, as reported for the case of Asmara–Massawa travel ($E_{cons}=$ 6.688 kWh). Finally, an environmentally sustainable solution, such as a 92 kWh/day photovoltaic plant, is proposed to power the service. Full article

The assessment of concrete infrastructures’ functionality during natural hazards is fundamental in evaluating their performance and emergency response. In this work, the alkali–silica reaction (ASR) in concrete is evaluated under the climate change impact. The ASR is greatly influenced by the weather parameters, such as temperature and humidity. Climate change has led the quickening of global warming and has caused extreme weather events in recent years. These events can create anomalies in weather and thus convey potential threats to the concrete infrastructures affected by the ASR. Capturing these extreme events is the key prerequisite for the precise quantification of the ASR chemophysics. This work develops a novel stochastic approach to understand the influence of stochastic temperature and humidity on ASR expansion. To assess the stochastic weather impacts on concrete, a physics-informed domain is developed by capturing the variably saturated porous medium of concrete. This is an effort to analyze ASR kinetics that integrates chemo-physical damage under extreme weather events. Results elucidate that the ASR-affected concrete would experience 83.33% more damage in 10 years than from seasonal change due to the stochastic weather impacts from climate change. This improved predictive model will guide the durable infrastructure materials design practices and enhance the resiliency of concrete infrastructures. Full article

Connected and Autonomous Vehicles (CAV) will change how road engineers design road pavements because they can position themselves within a traffic lane, keeping their position in the lane more precisely than human-driven vehicles. These vehicles will have lower lateral wandering, which can induce more damage to pavements, such as cracking and permanent deformation, than the conventional vehicles, with consequences for the infrastructures due to the increased cracking and reduced safety due to the rutting. Thus, it is essential to assess the wander effect on pavement performance to define policies for its implementation on CAV. This paper studies the impact of the lateral wander of the traffic on pavement performance, considering its fatigue and permanent deformation resistance. This impact can be used to define limits for the wander to minimize distresses on the pavement. The results of this study allow us to conclude that for a pavement with a 10 cm asphalt layer, the wander effect is more significant for fatigue life. A pavement life increase of 20% was observed for a wander of 0.2 m, while for 0.6 m, the fatigue life can increase up to 48%. For the permanent deformation, a pavement life increase of 2% for a wander of 0.2 m was observed, but for 0.6 m, the pavement life can be increased up to 34%. Full article

Recently, in Chile, infrastructure asset value has been incorporated into highway concession contracts. However, the current valuation model used for rigid pavements is not adapted to the standards and conditions of such projects. This study develops a valuation model for rigid pavements of interurban highway concessions and evaluates it in a case study. The proposed model captures the loss in asset value associated with the performance degradation over time, considering a typical Jointed Plain Concrete Pavement (JCPC) configuration. The value is calculated using performance indicators that represent the structural capacity and level of service provided to road users. The model represents a significant improvement compared to current asset valuation models used in highway concessions. It enables the public agency to objectively evaluate the preservation of asset value carried out by the private partner during the concession. Additionally, it could also be used as a tool to establish payments between infrastructure stakeholders. Some of the concepts applied could also be relevant for other highway assets existing in Public–Private Partnership (PPP) projects. Full article

This work presents a discussion of the basic properties of broken mineral limestone aggregates with the specification of the properties affecting the fracture toughness of concretes made with these aggregates. To determine the influence of the grain-size distribution of coarse aggregates for each concrete series, two types of aggregate grain were used, with maximum grain sizes of 8 mm (series of concrete L1) and 16 mm (series of concrete L2). Fracture-toughness tests were carried out using mode I fractures in accordance with the RILEM Draft recommendations, TC-89 FMT. During the experiments the critical stress-intensity factor $\left(K_{\mathrm{I}\mathrm{c}}^{\mathrm{S}}\right)$ and crack-tip-opening displacements ($CTOD\mathrm{c}$) were determined. The main mechanical parameters, i.e., the compressive strength (f_cm) and splitting tensile strength (f_ctm), were also assessed. Based on the obtained results, it was found that the grain-size distribution of the limestone aggregate influenced the concrete’s mechanical and fracture-mechanics parameters. The obtained results showed that the series-L2 concrete had higher strength and fracture-mechanics parameters, i.e.,: f_cm—45.06 MPa, f_ctm—3.03 MPa, $K_{\mathrm{I}\mathrm{c}}^{\mathrm{S}}$—1.22 MN/m^3/2, and $CTOD\mathrm{c}$ —12.87 m10⁻⁶. However, the concrete with a maximum grain size of 8 mm (series of concrete L1) presented lower values for all the analyzed parameters, i.e.,: f_cm—39.17 MPa, f_ctm—2.57 MPa, $K_{\mathrm{I}\mathrm{c}}^{\mathrm{S}}$—0.99 MN/m^3/2, and $CTOD\mathrm{c}$ —10.02 m10⁻⁶. The main reason for the lower fracture toughness of the concretes with smaller grain sizes was the weakness of the ITZ in this composite compared to the ITZ in the concrete with a maximum grain size of 16 mm. The obtained test results can help designers, concrete producers, and contractors working with concrete structures to ensure the more conscious composition of concrete mixes with limestone aggregates, as well as to produce precise forecasts for the operational properties of concrete composites containing fillers obtained from carbonate rocks. Full article

The Department of Highways (DOH), Thailand, has adopted both empirical and mechanistic approaches for flexible pavement analysis and design. Recently, the deflection-based design approach has been comprehensively reviewed by the DOH for the possible adoption of national design standards and practices. One of the key reasons is that Thailand’s road authorities, i.e., the DOH and the Department of Rural Roads (DRR), have considered the falling weight deflectometer (FWD) for the new construction and rehabilitation of road pavements. In addition, the FWD is widely accepted as the non-destructive test for deflection measurement and structural capacity evaluation. Ultimately, the implication of FWD deflections for in-house pavement analysis and design shall be developed and proposed to Thailand’s road authorities. Therefore, this study presents the deflection-based approach of flexible pavement design in Thailand. The FWD and a standard Thai truck were selected as the main loading applications in this study. A typical FWD loading stress of 700–800 kPa was practically adopted by the DOH and compared with a standard 10-wheel 25-ton truck with a tandem axle-dual wheel configuration with a tire pressure of 690 kPa. The layered elastic analysis was performed to calculate the pavement responses. The results suggest that the flexible pavement design based on a deflection-based approach is simple, practical, and conservative. Full article

Stone pavement structures (SPS), also known as stone roads or stone-paved roads, are road pavements constructed using stones as the primary surface material. Different types of SPS exist; historically, irregular-shaped stones with downward protrusions have been often exploited since regular-shaped stones were difficult to be produced. More recently, regular cuboid stones can be also used. Accordingly, in new construction and renovations of SPS, pavement designers must take an essential decision concerning the adoption of historical or regular stones. Nonetheless, it is often confusing which of the two types of stones should be employed, considering that historical and regular SPS follow the same theory and pavement design methods. Therefore, a comparison between the performance of these two types of SPS is required to support their design and maintenance. Moreover, SPS are limitedly investigated and, to the best of our knowledge, there are no research contributions that address this specific task. Accordingly, in the present study, after conducting a laboratory characterization and in situ structural survey by Falling Weight Deflectometer (FWD) on a SPS, a comparative analysis based on the Finite Element Method (FEM) was carried out for investigating the structural performance of the historical (H-SPS) and regular SPS (R-SPS) in urban trafficked areas, where SPS must withstand heavy traffic loads. Specifically, considering both typologies of SPS, the paper aims to model and investigate: (a) the mechanical behavior under loading (displacements, stress, and strain distribution), (b) failure criteria (stone warpage and separation between the stones and the mortar joint), (c) the joint efficiency between stones, and (d) to which extent the road subgrade stiffness may influence the performance of SPS. In addition to the pavement design perspective, the research also provides a short glance at the strengths and weaknesses of R-SPS and H-SPS from other sides, such as functionality, ease of maintenance, construction techniques, and cultural and historical values. Full article

Documentation of structural visual inspections is necessary for its monitoring, maintenance, and decision about its rehabilitation, and structural strengthening. In recent times, close-range photogrammetry (CRP) based on unmanned aerial vehicles (UAVs) and terrestrial laser scanners (TLS) have greatly improved the survey phase. These technologies can be used independently or in combination to provide a 3D as-is image-based model of the railway bridge. In this study, TLS captured the side and bottom sections of the deck, while the CRP-based UAV captured the side and top sections of the deck, and the track. The combination of post-processing techniques enabled the merging of TLS and CRP models, resulting in the creation of an accurate 3D representation of the complete railway bridge deck. Additionally, a 3D as-designed model was developed based on the design plans of the bridge. The as-designed model is compared to the as-is model through a 3D digital registration. The comparison allows the detection of dimensional deviation and surface alignments. The results reveal slight deviations in the structural dimension with a global average value of 9 mm. Full article

Transportation networks are one of the most vulnerable civil infrastructures during an earthquake and an estimation of traffic impacts in the post-earthquake scenario is a crucial aspect in the context of risk assessment and evaluation of remedial measures. In this paper, a methodology is presented, combining GIS tools, probabilistic seismic risk analysis and traffic simulation models, which is able to assess the direct and indirect (social) costs: bridge repairs, increase in travel time and a lack of accessibility. Operating issues related to the development and calibration of traffic models applicable to a damaged road network are carefully analysed and reviewed and an innovative approach to evaluate the social cost due to the lack of accessibility is also proposed. The developed modelling framework has been applied on a realistic bridge stock within a road transportation network in central Italy where local land-use data have been collected, extensive traffic surveys have been performed and a traffic model has been calibrated. A probabilistic risk analysis employing a ShakeMap derived from a historical real seismic event has been carried out. Full article

The structural performance of civil engineering infrastructures exposed to elevated temperatures has been investigated in many recent works. Some of these studies evaluated the residual mechanical behavior of masonry prisms subjected to high temperatures, as these specimens are simplified models (2–5 units in height) that can be easily produced and tested, in terms of operational and economic factors. However, there is no previous literature review on the mechanical properties of fire-damaged masonry prisms. Therefore, this paper presents an investigation of the current state-of-the-art on this topic. It provides a careful review of recent knowledge on the failure mechanisms, residual compressive strength, modulus of elasticity, and stress–strain behavior of masonry prisms made with different types of units, mortars, and/or grout after exposure to different types of thermal treatments. Based on the revised information, future research directions on the scientific field of masonry infrastructures are reported. Full article

This article addresses the issue of developing designs of resilient hydrological infrastructures for cities facing sea level rise in the Anthropocene. It undertakes short case studies of differently scaled cities, three in the Global North and three in the Global South. The aim is to investigate the current water management situations in order to reveal potentials for increased urban and environmental resilience. Cities are approached as complex adaptive systems (CAS) negotiating uncertainty that concerns designing for resilience, understood as viable transitions for their interlinked social, ecological, and technological systems (SETS). The main finding is that, despite obvious differences, the six cases are surprisingly similar. Potentials for increased hydrological resilience reside in design approaches that work differently with what is currently deprivileged and considered ‘merely’ peripheral. Peripheral cities and the peripheries of coastal cities are found to be of key rather than minor adaptive infrastructural import. To reprivilege the peripheral here means to adopt more dynamically flexible, long-term, decentralized, and nonanthropocentric urban design approaches to water and infrastructures. Specifically, this article advocates thinking about water via at least four critical displacements. These displacements point toward alternatives concerning excessively static and land-based designs, short-term planning, overly anthropocentric conceptions of the city environment distinction, and undue centrism in planetary urbanization of the Global North and Global South. In conclusion, this article presents a brief outlook to other cases which suggest that greater resilience potentials are likely to be found in planning for the complexly ecotone city. This works mostly bottom-up from the local regimes for water sensitive infrastructures to regional network designs that can engage with larger climatic and ecological landscapes. Full article

Vibratory rollers are mainly used for the near-surface compaction of granular media for a wide variety of construction tasks. In addition to the pronounced depth effect, vibratory rollers have offered the possibility of work-integrated compaction control (intelligent compaction) for decades. State-of-the-art measurement values for intelligent compaction (ICMVs) only take into account, if at all, a constant geometry of the contact area between the drum and soil. Therefore, this paper introduces a comparatively simple mechanical model, which describes the dynamic interaction between the vibrating drum and the underlying soil during compaction to investigate the influence of the changing geometry of the contact area on the motion behavior of the vibrating drum. The model is tested on realistic soil and machine parameters, and the results of the simulation with varying drum contact geometry are compared to a conventional simulation with a fixed contact geometry. The analysis shows that only a consideration of the varying drum contact geometry can map the dynamic interaction between the vibrating drum and soil sufficiently and provide a motion behavior of the drum that is in good accordance with the field measurements. Full article

Continuous research efforts have been developed in the literature to raise the sustainability components of the road infrastructure industry, i.e., reduce potential contaminants and augment financial profitability. In this regard, this investigation aims to explore the feasibility of producing Hot Mix Asphalt (HMA) with the inclusion of Recycled Concrete Aggregate (RCA) as a partial substitute for coarse Natural Aggregates (NAs). Thus, four different HMAs were considered, namely HMAs with coarse RCA contents of 0, 15, 30, and 45%. Specifically, the mechanical and sustainability properties of the asphalt mixtures were determined. On the one hand, the Marshall design parameters, resilient modulus, moisture susceptibility, rutting resistance, and fatigue life were addressed as mechanical properties. Meanwhile, regarding the sustainability properties, the environmental impacts and production costs were estimated using the Life Cycle Assessment (LCA) and the Life Cycle Cost Analysis (LCCA) methodologies, respectively. Consequently, the following conclusions were obtained: (i) as the coarse RCA content increases, the mechanical behavior of the HMA progressively deteriorates; (ii) this decrease in mechanical performance is acceptable up to a 15% RCA of coarse RCA, whereas for higher dosages this alteration is abrupt; and (iii) the RCA only generates sustainability benefits at a 15% replacement amount. Full article

A current problem in the construction industry is the lack of complex, scientifically based technological materials and design solutions for universal types of building materials, products, and structures, especially in terms of structures operating under conditions of aggressive chloride exposure. The aim of the study was to compare and evaluate the differences in the durability of conventional and variotropic concretes made using three different technologies, vibrating, centrifuging, and vibro-centrifuging, modified with the addition of microsilica, under conditions of cyclic chloride attack. Laboratory experiments and analyses using scanning electron microscopy were conducted. Vibro-centrifuged concrete showed the highest resistance to cyclic aggressive chloride exposure, which was expressed by a lower percentage drop in compressive strength compared to vibrated (87%) and centrifuged concrete (24%). The use of a microsilica as a modifying additive in the amount of 2–6%, instead of as a part of the binder, had a positive effect on the resistance of concrete to cyclic chloride attack. The most effective intervention was the introduction of additives in the amount of 4%. There was a reduction in the loss of strength of vibrated, centrifuged, and vibro-centrifuged concrete after 90 “dry-wet” cycles, as a result of the use of a modifying additive, in an amount between 45% and 55%, depending on the type of technology being used for producing a composite. The combined effect of the use of vibro-centrifuged concrete and microsilica led to a 188% decrease in strength loss resulting from cyclic chloride exposure. Full article