Special Issue "Connections in Concrete Volume 2"

A special issue of CivilEng (ISSN 2673-4109). This special issue belongs to the section "Structural and Earthquake Engineering".

Deadline for manuscript submissions: 20 May 2023 | Viewed by 5589

Special Issue Editor

Prof. Dr. Akanshu Sharma
E-Mail Website
Guest Editor

Special Issue Information

Dear Colleagues,

Connections in a concrete structure are established either in the form of anchors (or fasteners) connecting structural or nonstructural components to the structure, or in the form of reinforcement embedded in concrete or as part of a steel–concrete composite construction. To ensure structural integrity, it is essential to form a reliable connection between steel and concrete. A well-performing anchorage (fastening) is a must to ensure the interaction between the components connected to the structure and the structure itself. The required flow of forces from concrete to steel and vice versa is established through a sufficient bond between reinforcement and concrete. The anchorage zones are crucial for desirable interaction between concrete and steel structural members in a composite construction. Thus, in principle, the integrity of the entire structure relies heavily on the connections between steel and concrete.

With the advancement in production technologies, new products such as post-installed anchors, anchor channels, high-strength-reinforcing bars, nonmetallic reinforcement, etc. are being developed, and it is essential to verify their performance in concrete. Similarly, the compatibility of newly developed concrete-based materials such as high-performance concrete, fiber-reinforced concrete, geopolymer concrete, etc. with anchorages and reinforcement must be verified.

Practical and innovative solutions are needed for connections in real-life situations, and corresponding reliable design models are needed. In particular, the design models for anchorages are rather limited in scope, and many design issues need to be addressed. Some of these include various geometric configurations, anchorages under seismic loading, anchorages with supplementary reinforcement, anchor channels under different loading combinations, fatigue behavior, long-term performance, influence of corrosion on performance of anchorages, anchorages under extreme loading, etc. Not only is experimental research needed to answer these questions, but new numerical modeling approaches also need to be developed for deeper understanding of the topics.

Another very important aspect is the harmonization of design methods. For example, post-installed reinforcement can be designed either as an anchorage following the principles of fastening technology or as a reinforcing bar following the principles of reinforced concrete. However, the two principles generally lead to quite different design solutions. Similarly, the fastening technology principles require the base plate connecting different anchors to be rigid and stiff elastic, while composite construction principles recommend designing the base plate for yielding. These approaches need harmonization.

Often, the performance of structures under extreme hazards of earthquakes, impact or fire is dominated by the performance of their connections. Reliable design of connections against such hazards calls for performance-based approaches where the compatibility requirements between different components are accounted for.

Every type of strengthening needs a certain type of anchorage. The performance of the strengthening largely depends on the performance of the anchorage itself. Extremely high and challenging demands are imposed on the anchorages used in strengthening (e.g., seismic strengthening). Some of these include high forces, large crack widths, combined load and crack cycling, limited area and depth to develop the required resistance, limited access due to existing reinforcement, etc. Innovative strengthening methods along with anchorage techniques need to be developed that would allow the strengthening to serve its desired function and ensure the safe functioning of the structure.

The proposed Special Issue targets the abovementioned issues in the field of connections in concrete and offers a platform to researchers and experts worldwide to showcase their work. Currently, there is no journal that is dedicated to the problems of connections in concrete, and therefore, publications in this field are often directed to journals that provide a more general scope. In the experience of the proposer, it is often quite difficult to find a suitable journal to present the work in the field of connections in concrete. This issue would offer a new chance to hundreds of researchers working in the field of connections in concrete to publish their work. Additionally, since connections in concrete are, in general, not widely covered in classroom teaching, practitioners and consultants often look for innovative answers and solutions to their problems. This issue would offer them a place to look for such innovative solutions.

Dr. Akanshu Sharma
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. CivilEng is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • cast-in anchorages including anchor channels
  • bond between reinforcement and concrete
  • anchorages in composite construction
  • anchorages in structural strengthening
  • post-installed mechanical anchors
  • adhesive anchors and post-installed reinforcement
  • bond of special reinforcement in concrete
  • anchorages in special concretes
  • numerical modeling of anchorages and bond
  • code-based design models
  • performance-based approaches for anchorages
  • connections under seismic actions
  • connections under extreme situations (fire, impact)
  • connections under special actions.

Published Papers (8 papers)

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Research

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Article
Utilizing Polypropylene Fiber in Sustainable Structural Concrete Mixtures
CivilEng 2022, 3(3), 562-572; https://doi.org/10.3390/civileng3030033 - 25 Jun 2022
Viewed by 247
Abstract
Polypropylene fiber reinforced concrete (PFRC) is becoming more popular for structural purposes due to its durability, electrical resistivity, and mechanical properties. In this study, the influence of polypropylene fiber on the mechanical properties and ultrasonic pulse velocity (UPV) of fiber reinforced concrete (FRC) [...] Read more.
Polypropylene fiber reinforced concrete (PFRC) is becoming more popular for structural purposes due to its durability, electrical resistivity, and mechanical properties. In this study, the influence of polypropylene fiber on the mechanical properties and ultrasonic pulse velocity (UPV) of fiber reinforced concrete (FRC) were determined. Six different fiber volume fractions of polypropylene were considered in the experimental investigation with varying water–cement ratios and curing conditions. Non-destructive testing methods were utilized to determine the UPV of the PFRC. Available equations in literature for predicting the RFC’s compressive strength based on UPV values were selected. However, the computed values did not show good agreement with the compressive strengths obtained from the compression testing machine. It was confirmed that polypropylene fibers alter the propagation of UPV, and as a result, the existing equations do not accurately predict the compressive strength for PFRC. Therefore, a practical equation is proposed to accurately evaluate the compressive strength of PFRC with regard to UPV. Full article
(This article belongs to the Special Issue Connections in Concrete Volume 2)
Article
SC Wall-to-RC Basemat Over-Strength Connection: Behavior and Design
CivilEng 2022, 3(2), 503-524; https://doi.org/10.3390/civileng3020030 - 13 Jun 2022
Viewed by 258
Abstract
This paper presents results from experimental and analytical investigations conducted to evaluate the lateral load behavior and capacity of steel-plate composite (SC) wall-to-reinforced concrete (RC) basemat connections. Two SC wall-to-reinforced concrete basemat connection specimens were tested. These SC wall specimens had a height-to-length [...] Read more.
This paper presents results from experimental and analytical investigations conducted to evaluate the lateral load behavior and capacity of steel-plate composite (SC) wall-to-reinforced concrete (RC) basemat connections. Two SC wall-to-reinforced concrete basemat connection specimens were tested. These SC wall specimens had a height-to-length ratio of 0.6 and did not include boundary elements. The experimental results include the lateral force-displacement (V-Δ) responses of the specimens and observations of local damage such as steel plate local buckling and concrete crushing. 3D finite element models were developed and benchmarked using the experimental results. The benchmarked models were used to conduct analytical parametric studies, expand the database, and gain additional insights into the behavior of SC wall-to-RC basemat connections. The parameters included in analytical investigations were the wall aspect ratio (h/lw), reinforcement ratio (ρ), and wall thickness (T). Full article
(This article belongs to the Special Issue Connections in Concrete Volume 2)
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Article
Freeze-Thaw Behaviour of Post-Installed Bonded Anchors under Changing Climate Conditions
CivilEng 2022, 3(2), 332-346; https://doi.org/10.3390/civileng3020020 - 10 Apr 2022
Viewed by 565
Abstract
The freeze-thaw behaviour of bonded fasteners in concrete is assessed according to the European Assessment Document 330499-01-0601 with freeze-thaw condition tests, which include 50 temperature cycles with a duration of 24 h between −20 °C and +20 °C on constantly loaded anchors. It [...] Read more.
The freeze-thaw behaviour of bonded fasteners in concrete is assessed according to the European Assessment Document 330499-01-0601 with freeze-thaw condition tests, which include 50 temperature cycles with a duration of 24 h between −20 °C and +20 °C on constantly loaded anchors. It is assumed that one cycle is equivalent to the temperature difference, which a bonded fastener undergoes in one year. Based on an analysis of a 28-year time series of air temperature data for Austria respecting the Alpine region, a modified test protocol with a temperature amplitude of 65 °C between −20 °C and +45 °C is compiled without a predefinition of the number of cycles, in order to simulate temperature differences that occur under real climatic conditions. The experimental test results obtained for both test procedures demonstrate that the stabilization of the displacements for the modified test series occurred after 185 temperature cycles, compared to the 50 cycles for the standard method. This means that an increase in the temperature amplitude of 25 °C in the higher temperature range leads to an approximately 3.5 times higher number of required temperature cycles until displacement stabilization is reached. It is concluded that the definition of the used temperature range for freeze-thaw testing in conjunction with climatic data should be critically considered, in order to possibly adapt pure freeze-thaw tests towards experiments that take into account real annual temperature differences. Full article
(This article belongs to the Special Issue Connections in Concrete Volume 2)
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Article
Numerical and Experimental Investigation of Anchor Channels Subjected to Tension Load in Composite Slabs with Profiled Steel Decking
CivilEng 2022, 3(2), 296-315; https://doi.org/10.3390/civileng3020018 - 08 Apr 2022
Viewed by 537
Abstract
In curtain wall applications, anchor channels are frequently installed near the edge of composite slabs with profiled steel decking. The complex concrete geometry of these floor slabs affects the capacity of all concrete failure modes, but there are currently no guidelines or investigations [...] Read more.
In curtain wall applications, anchor channels are frequently installed near the edge of composite slabs with profiled steel decking. The complex concrete geometry of these floor slabs affects the capacity of all concrete failure modes, but there are currently no guidelines or investigations available on this topic. The main objective of the present research is to investigate how the position of anchor channels and the complex slab geometry influence the tensile capacity of anchor channels. For this purpose, an extensive numerical parametric study was performed using the 3D nonlinear FE code MASA, which is based on the microplane constitutive model. In order to validate the numerical results, an experimental program was carried out for some of the configurations possible in practice. Based on the results, recommendations are given for the reduction in the tensile capacity of anchor channels in composite slabs with profiled steel decking. Full article
(This article belongs to the Special Issue Connections in Concrete Volume 2)
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Article
Assessment of Quality of Fresh Concrete Delivered at Varying Temperatures
CivilEng 2022, 3(1), 135-146; https://doi.org/10.3390/civileng3010009 - 12 Feb 2022
Viewed by 776
Abstract
Concrete is increasingly utilized in the construction field in Southern Nevada. This area has an arid and hot summer and freezing cold winter conditions. These extreme conditions affect the properties of fresh concrete, which can cause cracking. Hot weather conditions may adversely affect [...] Read more.
Concrete is increasingly utilized in the construction field in Southern Nevada. This area has an arid and hot summer and freezing cold winter conditions. These extreme conditions affect the properties of fresh concrete, which can cause cracking. Hot weather conditions may adversely affect both fresh and hardened concrete properties. Even though practices can minimize the detrimental effects, good quality control of fresh concrete, from mixing to finishing, is crucial under hot weather conditions. The objective of the present study is to evaluate the seasonal consistency of concrete quality, considering strength and slump properties. Another objective of this research is to determine the relationship between the seasonal air temperature variations and those of freshly batched concrete. Results indicate that strength and slump remain constant with varying air and concrete temperatures during pour. Additionally, during the hot season (air temperature above 27 °C (80 °F)), fresh concrete’s temperature is lower than the air’s temperature, in contrast during the cold season (air temperature below 16 °C (60 °F)), fresh concrete’s temperature is higher than the air’s temperature. Fresh concrete temperature and air temperature are similar in the range of 60 to 80 °F. Therefore, to limit the use of additional water or admixtures it is recommended to pour concrete when the air temperature is in the range of 16° and 27 °C (60 to 80 °F). Full article
(This article belongs to the Special Issue Connections in Concrete Volume 2)
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Article
Concrete Overstrength: Assessment of Field Strength Seeking Insights for Overdesign Optimization
CivilEng 2022, 3(1), 51-65; https://doi.org/10.3390/civileng3010004 - 10 Jan 2022
Viewed by 775
Abstract
This study investigates the high contents of cementitious materials in Portland cement concrete and assesses the required (f’cr) and actual (σ) compressive strength of concrete specimens. A linear optimization technique identifies the required binder content to reach f’ [...] Read more.
This study investigates the high contents of cementitious materials in Portland cement concrete and assesses the required (f’cr) and actual (σ) compressive strength of concrete specimens. A linear optimization technique identifies the required binder content to reach f’cr. Standard specifications have required concrete overdesign (OD) for decades, but few studies have evaluated the actual magnitude of OD from field data. The compressive strength of 958 cylinders prepared in the field represented 8200 m3 of ready-mixed concrete with 300 and 450 kg/m3 of cementitious are analyzed. The actual OD appears to be 7 to 21% higher than required. The required 28-day compressive strength of concrete was achieved in less than seven days. Therefore, the content of the cementitious materials could be reduced by 6 and 17% so that concrete could reach f’cr without cementitious overconsumption. Reducing cementitious content is recommended to improve construction quality and optimize resource utilization. Among the main reasons for this recommendation are the estimated substantial long-term savings, increased concrete durability and more rational use of natural resources required to build the structures. Full article
(This article belongs to the Special Issue Connections in Concrete Volume 2)
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Article
Numerical Investigations on Non-Rectangular Anchor Groups under Shear Loads Applied Perpendicular or Parallel to an Edge
CivilEng 2021, 2(3), 692-711; https://doi.org/10.3390/civileng2030038 - 28 Aug 2021
Viewed by 1116
Abstract
Anchorages of non-rectangular configuration, though not covered by current design codes, are often used in practice due to functional or architectural needs. Frequently, such anchor groups are placed close to a concrete edge and are subjected to shear loads. The design of such [...] Read more.
Anchorages of non-rectangular configuration, though not covered by current design codes, are often used in practice due to functional or architectural needs. Frequently, such anchor groups are placed close to a concrete edge and are subjected to shear loads. The design of such anchorages requires engineering judgement and no clear rules are given in the codes and standards. In this work, numerical investigations using a nonlinear 3D FE analysis code are carried out on anchor groups with triangular and hexagonal anchor patterns to understand their behavior under shear loads. A microplane model with relaxed kinematic constraint is utilized as the constitutive law for concrete. Two different orientations are considered for both triangular and hexagonal anchor groups while no hole clearance is considered in the analysis. Two loading scenarios are investigated: (i) shear loading applied perpendicular and towards the edge; and (ii) shear loading applied parallel to the edge. The results of the analyses are evaluated in terms of the load-displacement behavior and failure modes. A comparison is made between the results of the numerical simulations and the analytical calculations according to the current approaches. It is found that, similar to the rectangular anchorages, and also for such non-rectangular anchorages without hole clearance, it may be reasonable to calculate the concrete edge breakout capacity by assuming a failure crack from the back anchor row. Furthermore, the failure load of the investigated groups loaded in shear parallel to the edge may be considered as twice the failure load of the corresponding groups loaded in shear perpendicular to the edge. Full article
(This article belongs to the Special Issue Connections in Concrete Volume 2)
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Review

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Review
Carbonation Potential of Cementitious Structures in Service and Post-Demolition: A Review
CivilEng 2022, 3(2), 211-223; https://doi.org/10.3390/civileng3020013 - 23 Mar 2022
Viewed by 580
Abstract
The construction sector is responsible for a great environmental impact. The cement industry, which is included in this sector, emits about 650 to 800 kg of CO2 per each tonne of cement produced, being one of the most polluting industries in terms [...] Read more.
The construction sector is responsible for a great environmental impact. The cement industry, which is included in this sector, emits about 650 to 800 kg of CO2 per each tonne of cement produced, being one of the most polluting industries in terms of greenhouse gas emissions. The cement manufacturing process releases about 7% of the total worldwide CO2 emissions. However, concrete and cement-based materials present CO2 uptake potential during their service life and post-demolition through carbonation processes. The carbonation reactions rate depends on several factors, namely type and content of cement, porosity of concrete, temperature, relative humidity and exposure conditions area. Therefore, to estimate the CO2 capture of concrete during its life cycle is not a straightforward calculation. Some studies have been developed using different methodologies in order to evaluate the CO2 potential of cementitious elements in service and post-demolition. This paper reviews the documented approaches that quantify the CO2 uptake of concrete over time, summarizing the assumptions adopted for each previous work. Overall, it was concluded that part of the CO2 emissions released during cement production are reabsorbed by concrete products during their life cycle, which partially offsets the environmental impact and reduces the CO2 footprint of the cement industry. Full article
(This article belongs to the Special Issue Connections in Concrete Volume 2)
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