Infill Model Research Articles

High-resolution lake infill time modeling at Jackson Lake, Wyoming (USA)

With growing climatic, anthropogenic, and environmental pressures on lakes and reservoirs globally, accurate quantitative sediment infilling estimates, or lake/reservoir lifespans, are essential to the effective management of these systems. Current methods used to model lake and reservoir infill timescales are limited in scope. This study presents refined data-rich infill models of Jackson Lake, WY (USA). Basin-wide seismic reflection profiles were used to obtain lake volume and total sediment isopach measurements. Radionuclide-dated sediment cores were collected to capture variability in sedimentation patterns, due in part to the lake’s bathymetric complexity. Three infill models were produced, including: (1) a model that uses radionuclide-based sedimentation rates and a 1-D linear infill, (2) a model that uses radionuclide-based sedimentation rates and a 3-D mass-based infill, and (3) a model that relies on sediment volume calculations and assumptions of basin age only. A fill-and-spill approach was utilized to ensure conservation of mass through each time step. All three models exhibited strong agreement on an infilling time of ∼30,000 years from present. Models developed in this study emphasize the need to accurately determine lake volumes and capture basin-wide complexity in sedimentation patterns, both of which are commonly poorly resolved in similar studies. Further development of data-rich lake/reservoir infill models could greatly benefit global lake and reservoir research critical to understanding engineered reservoir lifespans and carbon cycling in these systems. Further, accurate infilling data can assist in the development and application of effective policies for freshwater resource management and conservation, promoting the long-term sustainability of lake/reservoir systems.

Feasibility Study on Infiltration of Sidetracking Horizontal Wells in Fuyu Tight Oil Field

Abstract The Fuyu oil layer in well area 1 is a tight reservoir. Due to poor reservoir properties, conventional fracturing production wells have low production and rapid decline, with a recovery rate of only 2.22%.. Moreover, the surface of the well area is a wetland protection zone along the river. Under the new safety and environmental protection policies, new drilling is not allowed in the protection zone. In order to improve the development effect of the well area and increase the recovery rate, based on the geological and development characteristics of the oil reservoir, and in response to the problem of fast water breakthrough in east-west oil wells and ineffective water injection in non east-west oil wells in the Fuyu oil layer, the main oil layer with high well control degree, small well network density, and well-developed reservoir is selected. The original development well points are used to sidedrill stepped horizontal wells, combined with volume fracturing of tight oil horizontal wells, to avoid adjacent reserve losses, Exploring a new infill model for sidetracking horizontal wells in tight oil reservoirs in Fuyu, providing reference for effective development of similar reservoirs.

Effects of Infill Panels with Various Configurations on the Non-Linear Dynamic Responses of Reinforced Concrete Structures

Abstract: This study presents the effects of including infill panels on the non-linear dynamic response of a hypothetical reinforced concrete frame when subjected to an earthquake. Infill panels are represented by equivalent diagonal struts using three different configurations, i.e., single, double with three different connection locations with the beams, and triple struts. The main goal is to determine the simplest and most appropriate representation of the infill panels by analogous struts. The effect of panel sizes on the non-linear dynamic response of the structure is also presented in this work. The main results showed that including infill panels in the analysis reduced the natural period, roof displacement, and story drift ratio, increasing the roof acceleration and shear forces at the structure base. Utilizing the triple model and the double strut joined at the midspan of the beams showed a good agreement with those using the complete infill model.

Numerical modeling of weak infills with a central opening in high-strength concrete frames under pseudo-static loading using applied element method

Numerical modeling of weak infills with a central opening in high-strength concrete frames under pseudo-static loading using applied element method

Seismic fragility assessment of low-rise reinforced concrete frame: A comparative study of bare and infill model

Most of the residential structures designed in Nepal are low-rise reinforced concrete (RC) frames. They are designed following the guidelines given in the Nepal Building Code, especially, the mandatory rule of thumb. In analyzing and designing most of the reinforced concrete structures in the urban and semi urban areas of Nepal, only bare frame model is considered. The additional effect caused by the infill walls are neglected. In this research, a comparative seismic fragility assessment of low-rise RC frame is conducted. Two cases are assumed; with and without the consideration of the unreinforced masonry infill. Macro modelling approach is followed for modelling the infill effect. Results clearly indicate that the inclusion of the infills drastically reduce the roof displacement compared to the bare frame model during a seismic shaking. This is attributed to the fact that the inclusion of the infill imparts more stiffness to the structure during a seismic-shaking compared to the bare frame model and hence the displacement is reduced. Furthermore, seismic fragility of the frame structure is also overstated when the effect of infill is not taken into consideration. The inclusion of infills reduced the structural fragility to significant extent. In this regard, the bare frame model was found to be more vulnerable to seismic shaking compared to the infill model.

Finite Element Analysis of Different Infill Patterns for 3D Printed Tidal Turbine Blade

The fabrication route for tidal turbine blades has been compounded with the appearance of additive manufacturing; with the use of infill patterns, improvement of mechanical strength and material reduction for 3D printed parts can be obtained. Through finite element analysis and three-point bend tests, the optimal infill lattice pattern, and the viability of the shell–infill turbine blade model as an alternative to the conventional shell-spar model was determined. Out of a selection of infills, the best infill pattern was determined as the hexagonal infill pattern oriented in-plane. A representative volume element was modeled in ANSYS Material Designer, resulting in the homogenized properties of the in-plane hexagonal lattice. After validation, the homogenized properties were applied to the tidal turbine blade. The shell–infill model was based on the volume of the final shell-spar model which had a blade deflection of 9.720% of the blade length. The difference in the deflection between the homogenized infill and the spar cross-section was 0.00125% with a maximum stress of 170.3 MPa which was within the tensile strength and flexure strength of the carbon fiber with onyx base material. Conclusively, the homogenized infill was determined as a suitable alternative to the spar cross-section. The best orientation of the infill relative to the horizontal orientation of the blade was 0 degrees; however, the lack of trend made it inconclusive whether 0 degrees was the absolute optimal infill orientation.

Bidirectional effect of earthquake on low-rise RC frames with and without the consideration of In-plane effect of unreinforced masonry infill

Low rise RC frames make up the majority of residential structures built in Nepal. They are created in accordance with the requirements outlined in the Nepal Building Code, particularly the mandatory rule of thumb. Only the bare frame model is taken into consideration while analyzing and designing the majority of reinforced concrete structures in Nepal's urban and semi-urban areas. The infill walls' additional impact is often completely disregarded. Furthermore, there are no separate guidelines and standards set by Nepal Building codes for considering the impact of infill masonry during the analysis. Hence, in this study, reinforced concrete frame structures that commonly represent Nepalese low-rise RC frames is subjected to bidirectional (XY) shaking. Four types of models are considered and for each model, two cases are taken: those with and those without taking into account the in-plane effect of unreinforced masonry infill. The infills’ in-plane impact is modeled using a macro modeling approach. The response parameters under investigation are column rebar strain ductility and roof displacement. The results of the analysis clearly indicate that, when the infills’ in-plane effect is taken into account, both the roof displacement and the strain ductility demand of the column are greatly reduced as compared to the situation where it is not. Furthermore, it is obvious from the analytical fragility curves produced for the bare frame and infill models that the structure's vulnerability is exaggerated when the in-plane impact of infill is ignored.

Seismic behavior of novel low‐damage precast infill walls with sliding joints for reinforced concrete frame

AbstractThe detrimental infill‐frame interaction and vulnerable nature of the traditional solid infill walls might change the seismic behavior of the infilled reinforced concrete frames. To mitigate the adverse infill‐frame interaction and protect the fragile infill walls, in this paper, an innovative solution by partitioning the infill wall panels with low‐strength mortar sliding joints and uncoupling the infill from the boundary frame by flexible materials is presented for the reinforced concrete frames. Three 1/2 scale specimens designed in this context were examined experimentally and numerically, and a simplified model is developed for the proposed infill system. Test results show that the presented low‐damage infill system could effectively mitigate the adverse infill‐frame interaction and considerably prevent corner crushing or damage to the infill wall panels so that the reinforced concrete frame with the proposed infill system behaves similarly to the bare frame. Thanks to the working mechanism of the infill system, the proposed wall panels have a relatively high energy conversion efficiency from inter‐story displacement to the energy dissipation capacity of the infilled frame. Moreover, the developed simplified infill model could well capture the hysteretic behaviors of the proposed low‐damage infill system and improve the calculation efficiency. Parametric analysis results indicate that the friction factor of the sliding joints plays a significant role in enhancing the seismic behavior of the novel low‐damage infilled system.

Lagoonal reef island formation in Huvadhoo atoll, Maldives, highlights marked temporal variations in island building across the archipelago

Coral reef islands provide the only pedestals of human habitation in mid-ocean atoll archipelagoes. Understanding the environmental controls on island formation is critical for evaluating the future response of islands to environmental change and sea-level rise. This study examines the evolution of lagoonal reef islands in Huvadhoo atoll, southern Maldives. Using extensive ground penetrating radar (GPR) imaging of island sediment structure, combined with comprehensive analysis of island morphology, sedimentology, and 49 radiometric dates, detailed reconstructions of the evolution of two lagoonal islands is presented. A four-stage model shows a complex history of island formation across various stages of sea-level change during the late-Holocene: 1) lagoon infill occurring from ~3000–2000 years ago during a period of sea-level fall from the mid-Holocene highstand; 2) emergence of the island core through vertical aggradation during the latter stages of sea-level fall between ~2000 and 1500 yBP; 3) rapid lateral expansion of the islands between 1500 and 500 yBP coincident with the availability of sand-size sediments and during a period of sea-level oscillation; and, 4) subsequent minor expansion and modification of island shorelines through alongshore reworking of island sediments over the past 500 years. Results provide evidence of marked differences in the timing and mode of island formation within Huvadhoo atoll. Significantly, the formation of the lagoonal islands post-dates the formation of islands on the atoll rim by 1000–2000 years. Furthermore, the formation of sand islands over infilled shallow lagoons contrasts the formation of most atoll rim islands through the sequential deposition of storm-generated rubble deposited directly across reef surfaces that have reached their vertical growth limit. Results of lagoonal island formation in the southern Maldives provide comparative data for the northern Maldives. While the sequence of island formation follows the faro infill model identified in the northern archipelago, lagoonal islands in the south appear to have formed 2000 years after those in the north. This difference is likely to reflect lagged reef growth response from deeper foundations in the southern archipelago.

A new macro-model to analyse the combined in-plane/out-of-plane behaviour of unreinforced and strengthened infill walls

Reinforced concrete (RC) frame structures infilled with clay masonry walls represent a common construction practice worldwide. However, the significant interaction between in-plane (IP) and out-of-plane (OOP) response of the infill walls, and their brittle behaviour, can increase the seismic vulnerability of the building to both local and global mechanisms. Therefore, it is necessary to develop adequate tools to assess the seismic performance of infill panels. To this end, this paper presents a new macro-model for evaluating the IP/OOP behaviour of infill walls. The model consists of four strut elements, two for each diagonal of the wall, and two equal OOP masses placed in the centre of the panel; each strut is made of two beam-column elements that allow for the creation of a plastic hinge at the mid-span, where the non-linearity due to the IP/OOP interaction is concentrated and modelled through a nonlinear fibre section. The model is experimentally calibrated for four types of thin clay masonry panels, one unreinforced and three strengthened. To show the potential of the new infill model, a non-linear static analysis procedure is proposed for evaluating the lateral response of RC infilled frames. This simplified procedure is finally used in a parametric study that analyses various types of infilled frames. The results demonstrate the effectiveness of the proposed model, as well as of the strengthening solutions adopted to mitigate the IP/OOP interaction effects.

Bonding Strength Analysis of Multi-material and Multi-color Specimens Printed with Multi-extrusion Printer

This paper highlights the findings of multi-material application in 3D printed specimens. The work presents experimental results of multi-material, and multi-color-based 3D printed specimens by a multi-extrusion printer developed at the laboratory. It aimed to determine the bonding properties between the layers of various materials indicated with different colors. The samples were printed across multiple infill models and tested in the tensile and compression machine. The specimens were created with 10%, 25%, and 100% infill having single and dual colors material. Polylactic Acid (PLA), Acrylonitrile Butadiene Styrene (ABS), and Flex materials were used for printing various specimens with various colors. The layers were printed synchronously. The filaments were changed according to the predetermined algorithm. The experimental results showed that the mechanical properties of single, dual, and triple mate-rial specimens differed according to the reinforcement strategy. In addition, the mechanical property of the same material with different colors was identical.

QUANTIFYING THE IMPACT OF URBAN INFILL ON THE URBAN HEAT ISLAND EFFECT – A CASE STUDY FOR AN ALTERNATIVE MEDIUM DENSITY MODEL

Abstract. Urban Heat Islands (UHIs) impact the quality of life in many urban centres. Metropolitan areas of Australian cities and urbanised regional centres, in particular, show vulnerability towards UHIs due to challenging climatic conditions and the model of greater subdivision of established properties whereby backyards and mature trees are replaced with more residential dwellings and sealed areas. The measurements for the UHI mitigation, such as imposing reforestation, employing sustainable and medium density housing build form typology must be quantified. Simulation-based identification and mitigation of UHIs can be used for planning decisions. There are several advantages to use simulations. For instance, alternative subdivision design, building design and the placement of trees and other measures is only required in the digital twin. Experimenting with the digital twin saves resources and maximises the outcome by being able to quantify the heat reduction. The aim of this work is to quantify the impact of the current urban infill methods on UHI. We focus on an area that has gone through a process of re-subdivision that is bounded by roads within Perth, Western Australia. For the same area we propose an alternative design with an urban infill model based on a medium density housing guidelines with an improved green space allocation. While the current model shows significant effects of UHIs we could mitigate those effects in the alternative proposed model. In our simulation the hottest surfaces are roads with a temperature of approximately 45 °C at 2PM in the afternoon. In the current model close to 100% of the road surfaces reach this temperature. In contrast, in the alternative model only 45% of all road surfaces reach this temperature, significantly reducing the impact of UHI for pedestrian walking close by to those roads. At 2PM, the most frequent temperature of all surfaces for the current model is around 44 °C while the alternative’s model the most frequent temperature is approximately 28 °C – a difference of 16 °C.

Cyclic Numerical Modeling of Confined Masonry Walls Using Equivalent Strut Model

Confined masonry walls (CMWs) are generally used as a suitable type of lateral force resisting systems in earthquake prone regions. The RC confining members (tie-beams) in such walls are mainly used to provide integrity and increase the ductility of masonry buildings. Considering the inherent complexities of structural behavior of masonry materials and interaction between tie-beams and walls, modeling and analysis of CMWs is one of the challenging problems in the analysis of buildings under lateral loads. Among the building analysis methods, macro-modeling methods have always been considered by researchers due to their proper accuracy and efficiency. The purpose of this study is to modify and verify a suitable macro-model based on the equivalent strut model (Crisafulli infill model) for the cyclic analysis of CMWs. To this end, first, by comparing the behavior of CMWs with infilled frames and identifying their similarities and differences and using the relationships available in the literature, the specifications and parameters of this model are modified for CMWs (with and without opening) as well as CMWs with interior tie-beams. Then, based on the available experimental results of several CMWs and a 3D confined masonry building, the accuracy of the equivalent strut-based model in estimating the lateral stiffness and shear capacity of the specimens is discussed. The results show that it is possible to predict reasonably the overall response of CMWs by the modified equivalent strut model.

Assessment of existing steel frames: Numerical study, pseudo-dynamic testing and influence of masonry infills

Most of existing steel multi-storey frames in Europe have been designed before the introduction of modern seismic design provisions, hence they often exhibit low performance under earthquake loads due to their low lateral resistance and energy dissipation capacity. In addition, such structures often include rigid and brittle masonry infill walls that highly influence their lateral response and distribution of damage pattern. However, current procedures for the assessment of existing steel buildings in Europe, included in the Eurocode 8 – Part 3 (EC8–3), do not provide adequate guidance for the assessment of ‘weak’ steel frame with masonry infill walls. Moreover, most of available modelling approaches of masonry infills formerly developed for reinforced concrete (RC) structures do not properly represent the behaviour of infill walls in steel frames. An improved numerical has to be provided to satisfactorily mimic infill walls' behaviour in steel moment frames. To this end, an experimental and theoretical study was carried out within the framework of HITFRAMES (i.e., HybrId Testing of an Existing Steel Frame with Infills under Multiple EarthquakeS) SERA project. This paper firstly presents the limitations of current EC8–3 by conducting a code-based assessment on a case study steel moment frame using pushover analysis. Three different single strut models, widely used for simulating the presence of masonry infills in RC structures, are considered for the numerical analyses. The paper also presents the results of pseudo-dynamic (PsD) tests performed on a large-scale 3D steel frame with masonry infills. The capability of the different masonry infill models is successively evaluated by comparisons between numerical and experimental results. On the basis of the obtained results, recommendations on how to potentially improve the single strut model for masonry infills surrounded by steel frames are also provided.

Basin infill increases seaward sediment delivery in small, tide-dominated estuaries

Estuaries are sinks for sediment and evolve through a series of infill stages. In the early stages of infill, sediment is stored in the central basin due to ample accommodation space. In the late stages of infill, accommodation space decreases and a higher proportion of the sediment load is routed seaward. To predict changes in the seaward sediment delivery of estuaries, we must first understand how they evolve and how their storage capacity changes over time. In this study, we present an analysis of the current infill stage and relative importance of 15 small, tide-dominated estuaries draining into semi-enclosed Moreton Bay (MB), Australia. Our work shows that these estuaries all exist in a mature (i.e. late) stage of infill regardless of their catchment or antecedent basin size. Due to their high degree of infill and densely urbanised catchments, these estuaries are likely to be contributing a large amount of sediment into MB relative to their size. Using existing infill models from the literature, and Eprapah Creek estuary as a case study, we mapped vegetation and facies unit changes from 1955 to 2019 and collected sediment cores to develop a conceptual infill model for these small estuaries. We show there has been an increase in mangrove and alluvial units and a decrease in open water and saltmarsh habitats. These changes are likely a result of increased sediment bypassing due to the infilling of the estuary. Over 50 m of mangrove progradation at the shoreline has occurred on average since 1955, with progradation rates being highest adjacent to the estuary mouth. Our work illustrates that estuary morphology and infill stage can impact the seaward sediment delivery potential for small tide-dominated estuaries. This is of important for semi-enclosed shorelines globally as sediment is not as easily removed seaward compared to shorelines along the open ocean.

Effect of Masonry Infill Constitutive Law on the Global Response of Infilled RC Buildings

Masonry-infilled reinforced concrete frames represent a very common construction typology across the Mediterranean countries. The presence of infills substantially modifies the global seismic performances of buildings in terms of strength, stiffness, and energy dissipation. Although several research studies focused on the overall performances of infilled reinforced concrete frames, the modeling of infill panels remains an open issue due to the complex interaction between the infill and the frame and the uncertainties involved in the definition of the problem. In the present paper, an existing masonry-infilled RC frame designed according to obsolete seismic codes is chosen as a case study. A refined three-dimensional finite element model is built for performing nonlinear static and time-history analyses in order to investigate some significant aspects related to the modeling of infills. In particular, it is investigated the effect of different infill constitutive models on the seismic performance of infilled RC building expressed in terms of engineering demand parameters such as interstory drift ratios and peak floor accelerations, and on the generation of damage fragility curves.

Studies on Seismic Performance of Low, Medium and High Rise Reinforced Concrete Frame with Infill

This paper studies the pushover analysis of Low, Medium and High Rise Reinforced Concrete (RC) frame with infill. Pushover analysis is nonlinear static procedures for the seismic assessment of Low, Medium and High Rise Reinforced concrete (RC) structures, due to its simplicity, efficiency in modelling and low computational time. Four storey, Eight storey and Twelve storey RC frames with infill models were considered in this analysis. This pushover analysis was carried out for default hinge properties available in program based on FEMA 356. The seismic performance of RC frame with infill was measured in terms of base force and displacement curve, performance point, number of plastic hinges at different performance levels.

Strengthening of existing RC buildings by using autoclaved aerated concrete infill wall

ABSTRACT The objective of this study is to use autoclaved aerated concrete (AAC) for infill walls in existing buildings that are unsafe for earthquakes to increase their stiffness. The study included two topics; the first topic introduced six models using AAC in buildings resistance to earthquakes and the effect of self-weight of the buildings comparing bare frame clay partition masonry model (1), bare frame AAC partition masonry model (2), reinforced concrete frames clay infill wall model (3), reinforcement concrete frames AAC infill wall model (4), reinforcement concrete frames AAC infill wall core model (5), reinforcement concrete frames AAC infill wall first and second floors model (6). ETABS software was used to investigate all frame models. Results of the study revealed that AAC infill wall decreases base moment, base shear and displacement. On the other hand, second topic presented five models of single reinforcement concrete frame under lateral loading, considering effect of anchored and unanchored AAC infill wall and clay infill wall. These models are bare frame model (a), RC frame with clay infill wall unanchored model (b), RC frame with AAC infill wall unanchored model (c), RC frame with clay infill wall with anchors model (d), RC frame with AAC infill wall with anchors model (e). Using finite element software (ANSYS WORKBENCH 18.2) failure load, displacement and ductility were presented for all five frames. The results showed that the ‘RC frame with AAC infill wall with anchors’ model gives the biggest failure load whereas displacement and ductility are the lowest.

Triassic sand supply to the Slyne Basin, offshore western Ireland – new insights from a multi-proxy provenance approach

To assess provenance data and derive basin infill models with a higher level of certainty it is vital to understand how minerals used in sedimentary provenance behave in the sedimentary system. A multi-proxy approach helps ensure rigour in how provenance data are interpreted. U–Pb geochronology of refractory zircon and relatively less stable apatite, and Pb isotopic analysis of labile K-feldspar are employed in this study to reassess the provenance of Triassic sandstones in the Slyne Basin, offshore western Ireland. This approach aims at reducing the potential bias in each method, producing a complementary dataset. U–Pb zircon and apatite geochronology yields Archean–Paleoproterozoic ages, Caledonian ages and previously unrecognized Permo-Triassic ages. Pb isotopic analysis of K-feldspar does not identify the Permo-Triassic as a source. The detection of Permo-Triassic-aged detritus may suggest that volcanism was more widespread than previously recognized. These results support the hypothesis of a Triassic drainage divide between the basins offshore western Ireland and those onshore Britain and in the Irish Sea. Sand supply was dominantly from the north, with significant input from the flanks of the basin, and previously unrecorded sources, such as Permian-aged rocks, playing an important role. The provenance signal is consistent and homogenized throughout the sampled sequence indicating that the drainage system was long-lived. Supplementary material: Details of laboratory and sample preparation, data tables and summary pie charts for each sample are available at https://doi.org/10.6084/m9.figshare.c.4571096

A new macromodel for the assessment of the seismic response of infilled RC frames

SummaryNumerous research studies have proved that numerical models aiming at an accurate evaluation of the seismic response of RC framed buildings cannot ignore the inelastic behaviour of infills and the interaction between infill and frame elements. To limit the high computational burden of refined non‐linear finite element models, in the latest decades, many researchers have developed simplified infill models by means of single or multiple strut‐elements. These models are low time‐consuming and thus adequate for static and dynamic analyses of multi‐storey structures. However, their simulation of the seismic response is sometimes unsatisfying, particularly in the presence of infill walls with regular or (particularly) irregular distributions of openings. This paper presents a new 2D plane macro‐element, which provides a refined simulation of the non‐linear cyclic response of infilled framed structures at the expense of a limited computational cost. The macro‐element consists of an articulated quadrilateral panel, a single 1D diagonal link, and eight 2D links and is able to model the shear and flexural behaviour of the infill and the non‐linear flexural/sliding interaction between infill and surrounding frame. The proposed macro‐element has been implemented into the open source software OpenSees and used to simulate the response of single‐storey, single‐span RC infilled frame prototypes tested by other authors. The above prototypes are selected as made of different masonry units and characterised by full or open geometric configuration.