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Translation abstract Thermal load assumptions for precast insulated sandwich panels considering modern construction methods – Insights from experimental and numerical studiesPrecast insulated sandwich panels are an essential component of modern precast concrete constructions. From an engineering perspective, these multi‐layered components represent highly complex load‐bearing systems, with the facing shell often simplistically treated in practice. The increasing use of highly efficient facing panels with thicknesses of up to 20 mm requires an urgent revision of current practices and design guidelines. A precise consideration of thermally‐induced climatic influences is crucial for economical and safe structural design. As part of a research project funded by Zukunft Bau of the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB) and led by the Chair of Concrete and Masonry Structures at the Technical University of Munich (TUM), comprehensive experimental and numerical investigations into the thermal responses in the cross‐sections of the facing shells on sandwich walls have been conducted. The findings inform proposals for cross‐section‐dependent thermal load assumptions for sandwich panels. [ABSTRACT FROM AUTHOR]

Precast construction offers multiple benefits, encompassing heightened productivity, an enhanced working environment, and significant waste reduction. Timely delivery of precast components (PCs) is of paramount importance in the successful execution of construction projects, mainly because processes involving precast prefabrication are identified frequently as critical activities in the majority of cases. However, current scheduling models for precast production need to meet the demands of dynamic environments in which construction projects contend with uncertainties. Consequently, it is essential to investigate and develop more-resilient and flexible scheduling approaches to address these challenges effectively and guarantee the timely delivery of precast components in these dynamic construction scenarios. To address these challenges, this study introduces an approach that integrates precast tracking, positioning, progress monitoring, and analysis among the multiple stages undertaken by project communities. Each component's status is updated dynamically in the cloud-based Building Information Modeling (BIM) platform using radio-frequency identification (RFID) and ultrawideband (UWB) technologies. Moreover, the collected data are updated to a dynamic production planning engine to be analyzed more accurately and flexibly for prefabrication, fitting-out, installation resources, workerpower planning, scheduling, and execution. To verify the efficiency of the proposed system, on-site testing was performed on a prefabricated prefinished volumetric construction (PPVC) residential building project. The findings show that a precast component can be tracked precisely on-site and that the sensor network can deliver trustworthy data. This research adopted an innovative and comprehensive methodology, centering on the transmission of real-time data collected via RFID and UWB sensing to enable dynamic scheduling in precast construction. By facilitating dynamic planning, scheduling, optimization, and progress monitoring, the study introduces a paradigm shift in construction project management, markedly improving the efficiency and effectiveness of project execution. Practical Applications: Precast construction, known for its efficiency and sustainability, faces a key challenge in ensuring the timely delivery of precast components. This is crucial because PCs assembly often represents critical activities in construction projects. Current scheduling engines struggle to adapt to the unpredictable nature of construction environments, which frequently deal with uncertainties. This study presents an innovative approach that integrates tracking, positioning, and progress monitoring of PCs using advanced technologies. By employing radio-frequency identification and ultrawideband sensors, PCs' status is updated in real-time on a cloud-based Building Information Modeling platform. These data are uploaded into a dynamic production scheduling engine, enhancing the accuracy and flexibility of scheduling and execution, especially for prefabrication and installation stages. This approach was tested in a real-world prefabricated prefinished volumetric construction residential building project. The results demonstrate the system's ability to locate PCs on-site precisely and provide reliable data. This holistic strategy not only allows for dynamic scheduling, optimizing workerpower and resource allocation, but also enhances overall project management. This leads to more-effective planning, optimization, and monitoring of progress, significantly improving project execution in precast construction environments. [ABSTRACT FROM AUTHOR]

Load transfer in structural elements of RC constructions and the behavior of such constructions are basically dependent on the detailing of both the structural elements and their connections. Assessing analytically the characteristics and behavior of such structural elements and their connections under likely occurring loads is an important issue. For common detailing of footings in steel and precast structures, longitudinal reinforcement of foundation beams is bent horizontally and spliced with reinforcement of cast-in-place footings to insure an adequate juncture for load transfer. In this study, as concerned with reducing construction time and cost, instead of bending longitudinal reinforcement bars of both, beams and footings, headed reinforcement bars are adopted. By doing so, a discontinuity region is created where longitudinal bars of footings become eccentric to those of beams that are embedded in the footings. To allow the flow of tensile forces from longitudinal bars of beams to longitudinal bars of footings, a set of reinforcing ties is provided between them. As such setting of headed reinforcement bars is not common, thorough investigations have been carried out to confirm the relevance of the proposed tie reinforcement. In this paper, results of a finite element numerical investigation of pulled-out eccentrically spliced longitudinal headed bars with different detailing of transverse reinforcement, proposed for precast beam-cast-in-place footing connection, are presented and compared to test results. The elaborated modeling could fairly reproduce the global behavior of the six specimens, where the numerical results acceptably approached the experimental results in terms of initial stiffness, ultimate strength, crack pattern and strain of reinforcement.

Precast construction is a productivity-improving technology in the architectural, engineering, and construction industry that improves construction efficiency by combining factory-based manufacturing and lean assembly. Many international efforts have encouraged the adoption of this approach. This study presents an integrated Building Information Modelling (BIM) with technological automation interoperability to enable generative design and prefabrication for precast buildings. A generic BIM-based graph representation is established to explicitly formulate buildings' spatial and geometric features. Following this, a graph-constrained layout generator is developed, with a generative modelling algorithm and graph convolutional neural network, to extract pairwise spatial-geometric features for generating the optimal precast layout. This is followed by semantic enrichment of BIM data (i.e., Industry Foundation Classes) with precast data schema to facilitate data transformation for prefabrication automation until site delivery. The holistic approach presented in this study empowers pre-construction planning optimisation and fabrication automation in precast construction.

Fast construction method for bridges with long‐span precast girders made of C80/95 Fast‐track construction with the least possible disruption to traffic in connection with minimizing congestion‐related CO2 emissions represent a new design objective for concrete bridges in the context of sustainable construction and climate protection. The following article reports on the potential of the prestressed high‐strength concrete C80/95 for precast girders in an overpass structure over a 6‐lane motorway without the need for an intermediate support in combination with the use of precast elements also for the abutments as a pilot project. The article concludes with the remarkable result of a study on how much CO2 emissions can potentially be avoided by shortening the construction time for such structures. [ABSTRACT FROM AUTHOR]

A novel composite floor consisting of an upper chord of a grouted square steel tube truss and a lower chord of a reinforced concrete slab is proposed to address existing problems with precast composite floors, such as a complex construction process, high cost, significant resource consumption, and severe environmental pollution. Sixteen-point loading tests were carried out on five simply supported one-way slabs to simulate the stress state of the floor under a uniform load and to investigate the stiffness, cracking moment, load-carrying capacity, and failure mode of the composite floor system. The results showed that the composite floor system exhibited ductile failure, with cracks uniformly distributed at the bottom of the slab; additionally, the grouted steel tube did not experience uplift or out-of-plane buckling, and the truss welds did not fracture, indicating that the composite floor system still had further deformation capacity and load-carrying capacity with satisfactory stress conditions. After unloading, the residual deformation of the composite floor accounted for 28% to 36% of the maximum deflection, demonstrating good deformation recovery ability. The bottom slab thickness and truss height are key parameters that influence the new composite floor, and increasing the two parameters enhances the cracking load, deformation resistance, and flexural capacity of the composite floor, with a significant improvement achieved by increasing the truss height. The floor slab should have a minimum thickness of 60 mm, as required by China's Code for Design of Concrete Structures, and the truss height-to-span ratio should be 1:30, which meets the deformation and load-carrying requirements of the floor and conforms to the design concept of green buildings. [ABSTRACT FROM AUTHOR]

Production scheduling plays a crucial role in the prefabricated construction productivity and on-time delivery of precast components (PCs). However, previous studies mainly focused on the static scheduling of single production line without considering the demand variability in practice. To achieve dynamic production planning, a Two-level Rescheduling Model for Precast Production with multiple production lines is developed to minimise the rescheduling costs based on genetic algorithm, from the two levels of (1) selection of production line and (2) rescheduling of jobs based on PCs’ priority. Further, two scenarios of different and shared mould types are investigated to represent real-world production environments. Finally, a real case study is conducted to test the validity of proposed rescheduling model. 58.1 and 48.5% cost savings are achieved by comparison to no response to changes and heuristic rescheduling methods, respectively. This research contributes to the precast production theory by expanding the insight into dynamic rescheduling with multiple production lines. The methodology will promote the on-time delivery of PCs and enhance the dynamic precast production management. [ABSTRACT FROM AUTHOR]

A novel composite floor consisting of an upper chord of a grouted square steel tube truss and a lower chord of a reinforced concrete slab is proposed to address existing problems with precast composite floors, such as a complex construction process, high cost, significant resource consumption, and severe environmental pollution. Sixteen-point loading tests were carried out on five simply supported one-way slabs to simulate the stress state of the floor under a uniform load and to investigate the stiffness, cracking moment, load-carrying capacity, and failure mode of the composite floor system. The results showed that the composite floor system exhibited ductile failure, with cracks uniformly distributed at the bottom of the slab; additionally, the grouted steel tube did not experience uplift or out-of-plane buckling, and the truss welds did not fracture, indicating that the composite floor system still had further deformation capacity and load-carrying capacity with satisfactory stress conditions. After unloading, the residual deformation of the composite floor accounted for 28% to 36% of the maximum deflection, demonstrating good deformation recovery ability. The bottom slab thickness and truss height are key parameters that influence the new composite floor, and increasing the two parameters enhances the cracking load, deformation resistance, and flexural capacity of the composite floor, with a significant improvement achieved by increasing the truss height. The floor slab should have a minimum thickness of 60 mm, as required by China’s Code for Design of Concrete Structures, and the truss height-to-span ratio should be 1:30, which meets the deformation and load-carrying requirements of the floor and conforms to the design concept of green buildings.

Slender and elegant integral bridge in Leipzig – The New Messebrücke The new Messebrücke connects the old trade fair grounds and the Wilhelm‐Külz‐Park in front of the Leipziger Völkerschlachtdenkmal across the German Railway. The structure is part of the striking urban development and landmarked visual axis between the New Town Hall and the Völkerschlachtdenkmal, most of which has avenue architecture. The new bridge is an replacement for an old road bridge into the form of a 3‐span fully integral frame structure with high architectural requirements consisting of reinforced and prestressed concrete. The cross section is designed as a very slender twin rib deck with widely cantilevered deck slab. The inclined abutment walls were concreted directly against the hydraulic binder‐stabilized embankment. Self‐compacting concrete was used for the inclined piers and abutment walls. Due to short rail traffic closures and in order to avoid elevated and very costly construction with falsework the midspan above the railway consists of longitudinal and transverse precast elements, which were supplemented with in‐situ concrete. The side spans are casted‐in‐place on formwork. The following describes the architectural and structural design, the construction and erection of the fully integral frame bridge. [ABSTRACT FROM AUTHOR]

Effects of imperfections on joint bearing capacity of segmented tower structures Hybrid tower structures for wind turbines have become established in recent years, especially for turbines with large hub heights. The upper part of these towers consists of steel sections, whereas the lower part is made up of prestressed precast concrete rings. The horizontal joints between the precast concrete elements are usually designed as dry joints. Due to the lack of a compensation layer in the joint, increased demands are made on the accuracy of the joint surfaces. From measurement data of real segments of wind turbines, it could be deduced that the joint surfaces show imperfections with respect to the cross‐sectional shape and flatness. Numerical simulations were used to investigate the influence of these imperfections on the joint support behaviour under combined loading of prestressing, bending and torsion. It is shown that, depending on the type of imperfection and the degree of prestressing, imperfections can have a considerable influence on the joint load‐bearing behaviour. [ABSTRACT FROM AUTHOR]

Precast concrete pavement (PCP) has proven itself to be one of the most efficient methods for repair and replacement of concrete pavement, as well as for construction of new pavement in the areas of heavy traffic. The application of PCP ensures fast construction of concrete pavement without compromising the quality of concrete. This paper provides a brief of various types of PCP that have been used worldwide and their application in the repair of damaged pavement, continuous construction of pavement, Airfield application and temporary pavement construction. It further discusses critical aspects of PCP that require careful analysis prior to its field implementation. The paper specially focuses on panel dimensioning, load transfer mechanism, lifting arrangement, stacking arrangement, transportation and base preparation for PCP. Suitability of different types of PCP for varying site conditions has been discussed. Innovative developments related to PCP and the future scope of this technology have also been discussed.

This paper aims to explore the seismic performance of a novel earthquake-resilient bridge column with replaceable elements, including external ultra-high-performance concrete (UHPC) cover plates and internal steel dissipaters, based on a numerical model including local and overall levels. The overall model was established to assess the seismic behavior of the bridge columns considering the buckling behavior of steel dissipaters adopting the modified material constitutive relationship, of which the parameters were determined according to the results of the local model. The numerical model was verified with reported experimental results. A parametric analysis was conducted to investigate the effects of three parameters. The results show that the numerical model can effectively evaluate the seismic performance of the bridge columns. The buckling behavior of steel dissipaters dominates lateral deformation capacity of the bridge columns. The steel dissipater's initial defect direction and gap gradient can accelerate the failure of cover plates. Reasonable upper and lower limits are required for the length-to-diameter ratio of the fuse part as well as the gap between the fuse part and surrounding concrete, while only a suitable lower limit is needed for the thickness of cover plate to ensure the superior seismic performance of the bridge columns. [ABSTRACT FROM AUTHOR]

Critical path method (CPM) still remains the most commonly used scheduling technique, despite many studies confirming its shortcomings for scheduling repetitive construction projects. This research evaluated the case study of an alignment-based precast water canal erection project, which was originally planned with CPM and analysed the suitability of using linear scheduling method (LSM) for the same project. The case study project was scheduled using both CPM and LSM tools and the results were compared in terms of estimated total duration and resource cost. The results showed that LSM produced a saving of 10 days in total duration and 20.07% in estimated resource cost over CPM. LSM also proved to be the better tool in terms of other schedule attributes like resource assignment, levelling, visualisation, etc., for alignment-based projects. LSM can be highly efficient for scheduling different types of repetitive construction and offers benefits like better workflow and continuous resource usage. [ABSTRACT FROM AUTHOR]

Today's cement concrete industry is a major polluter. Cement, used as a binder in cement concrete, is made by high-temperature combustion, which raises atmospheric CO2 levels and contributes to climate change and natural resource depletion. As raw supplies diminish, several governments begin to levy carbon taxes. Numerous research have been undertaken to produce an innovative and ecologically advantageous construction material known as Geopolymer concrete (GC) in order to minimise and eliminate greenhouse gas emissions. In order to connect coarse aggregates (CA), fine aggregates (FA), and other materials in GC and improve concrete quality while using fewer natural resources, it is essential to replace cement with a byproduct substance rich in silicon and aluminium, such as red mud, fly ash (FA), rice husk ash (RHA), silica fume (SF), ground granulated blast furnace slag (GGBS), and others, activated by a high alkaline solution (AS). In this study were surveyed online and precast self-compacting geopolymer concrete's sustainability was examined. The data underwent factor analysis. Principal component analysis is used to extract factors. According to the research, there are 9 key variables to consider: Reduction in Carbon Footprint, Utilization of Waste Materials, Environmentally Friendly, Reduce Water usage during production, Low Maintenance, Augmentation of Mechanical Properties of Concrete, Natural Materials, Cost Effective, Reduction in Energy consumption during production. These are the nine primary sustainability criteria of Self-Compacting Geopolymer Concrete for Precast Construction.

The purpose of this study is to investigate the applicability of the high-ductile fibre cementitious composite to develop seismically improved reinforced concrete columns. The high-ductile fibre cementitious composites were fabricated to exhibit high-ductile tensile strains as above 2.0% with sustaining the tensile stress after cracks and to develop multiple micro-cracks while avoiding crack localisation. In order to seismically improve the reinforced concrete column, the precast box made of the high-ductile fibre cementitious composite was locally used at the flexurally critical region in the column plastic hinge zone, and the construction process was also proposed. In seismic capacity evaluation of the developed column, cyclical loading tests were carried out by using four column specimens fabricated. It was revealed, from experiments, that the developed reinforced concrete and the high-ductile fibre cementitious composite columns showed an improvement of the seismic capacity of the column as well as a minimisation of flexural and shear cracks in the bending critical region of the column.

Advanced torsional bearing model of external prestressed circular ring segments with dry joints The frequent application of dry joints as connection technology in the field of wind turbine towers and prefabricated bridge construction demands improvement of the calculation model of these connections. This article describes the development of an interaction model for the determination of torsional load‐bearing capacity under shear forces and bending loads applied on circular ring segments. The model considers both the interaction with all loading conditions and the alternating effect of gaping joints due to the bending load. Previous models describe the load‐bearing capacity of circular ring segment joints insufficiently or without considering interactions with shear forces or the bending moment. Finally, the results of the developed model are compared to numerical calculations showing satisfactory agreement. [ABSTRACT FROM AUTHOR]

Model development for torsion stressed circular ring segments with dry joints The segment construction method for wind turbine towers has established itself in the production of large hub heights in the form of hybrid constructions. Hybrid towers consist of steel pipes in the upper part and usually pre‐stressed reinforced concrete segments in the lower part. The horizontal joints in the reinforced concrete structure are generally constructed as a grinded dry joint without shear serrations. Therefore, shear forces in the joints can only be transmitted by friction, especially for the calculation of the ultimate limit state (ULS), in which case torsion is relevant and the joints open due to a bending load. The current theories are based on the known torsion theories according to Saint‐Venant, which are not fully applicable to this construction method. Based on the theoretical considerations from [1], a torsion support model for circular ring segments with dry joints is developed in this paper. Subsequently, this model is compared with numerical simulations and experimental results. [ABSTRACT FROM AUTHOR]

Precast concrete pavement (PCP) has proven itself to be one of the most efficient methods for repair and replacement of concrete pavement, as well as for construction of new pavement in the areas of heavy traffic. The application of PCP ensures fast construction of concrete pavement without compromising the quality of concrete. This paper provides a brief of various types of PCP that have been used worldwide and their application in the repair of damaged pavement, continuous construction of pavement, Airfield application and temporary pavement construction. It further discusses critical aspects of PCP that require careful analysis prior to its field implementation. The paper specially focuses on panel dimensioning, load transfer mechanism, lifting arrangement, stacking arrangement, transportation and base preparation for PCP. Suitability of different types of PCP for varying site conditions has been discussed. Innovative developments related to PCP and the future scope of this technology have also been discussed. [ABSTRACT FROM AUTHOR]

Precast concrete building cores are a widely used lateral load resisting system in low and mid-rise multi-storey buildings. However, despite their widespread use in countries like Australia or New Zealand, a very little research or experimental testing has been undertaken to assess their lateral drift behaviour. This article will present the findings and observations of a recent experimental testing programme into reinforced concrete precast building cores, which included three large-scale 'box-shaped' precast building core specimens. Adjacent panels in each specimen were connected together using welded stitch plate connections and then connected to foundation blocks on the top and bottom using grout tube connections. The results of the testing showed that the welded stitch plate connections were too flexible to allow full composite action to be developed in the cross-section, which meant the precast building core specimens were around 25% more flexible than an equivalent cast in-situ version. The testing also highlighted common detailing and construction deficiencies that can severely inhibit the ductility of the core. [ABSTRACT FROM AUTHOR]

A novel connection adopting lap-spliced large-diameter bars and ultra-high performance concrete (UHPC) grout was developed to accelerate the assemble progress of precast bridge columns. The precast bridge column adopting the connections was testified to be on a par with the monolithic concrete counterpart in terms of seismic performance in previous research. This paper aims to develop a numerical model to further investigate the seismic behavior of the proposed bridge column considering the bar-slip effect. A finite element model was established for the bridge columns considering deformation components of flexure, shear, and bar-slip. The bond behavior between the deformed bar and UHPC was defined using a new practical model, which was developed based on a pullout test including five specimens in this research. The established finite element model was verified by the cyclic loading test in literature in terms of the overall hysteretic curve and local responses. The validated model was used to conduct parametric analysis to study the contributions of the different deformation components to lateral deformation as well as the effects of large-diameter bars on seismic performance. Results show that all the pullout specimens have the tensile fracture of bars, which indicates that the development length of 5 times bar diameter is sufficient for deformed bars in UHPC when the bar diameter is no more than 32 mm. The practical model is effective to consider the effects of the slip between the deformed bar and UHPC. The finite element model can predict the overall hysteretic curve and local responses at different drift ratios. The bar-slip has a considerable even dominative contribution to the lateral deformation of the proposed bridge column. Larger bar diameter can enhance deformation capacity as well as reduce energy dissipation and residual drift ratio. [ABSTRACT FROM AUTHOR]

Precast reinforced concrete building structures are widely used in the Portuguese industrial stock and throughout Europe. Beam-to-column connections are a key component in this type of structure. However, they are also the source of significant damage, as reported in recent earthquakes. Different configurations are common, such as using a dowel, neoprene or just assuming a concrete-to-concrete interface. Both are characterized by a low deformation and strength capacity, presenting a significant vulnerability against seismic actions. Based on this motivation, a novel low-cost and easy-to-apply retrofit connection is herein proposed to reduce this vulnerability. Shear tests were performed to compare the performance of a retrofitted connection with the as-built configuration (i.e. concrete-neoprene interface). The experimental tests showed a good performance of the proposed retrofit solution, emphasizing the importance of this solution in frictional connections to control horizontal displacements. With the use of this solution, it was possible to overcome the resistance obtained in the connections with dowels in the most vulnerable direction, obtaining a 49% increase in the lateral resistance in the most vulnerable direction (loss of support of the beam on the column) concerning that which was verified in the friction-only connection. • The work addressed the vulnerability of precast RC beam-to-column connections. • A novel retrofit connection was proposed to enhance the deformation and strength capacity of precast RC connections. • The solution aimed to be low-cost and easy to apply. • The retrofitted specimens exhibited no damage in the beam and column, successfully protecting the reinforced concrete elements. • The retrofitting solution significantly increased the stiffness and strength in the pull direction. [ABSTRACT FROM AUTHOR]

Off-site construction is a rising topic in both academic research and industrial applications because of its potential to bring about high-level of industrialization, environmental benefits, and sustainability in the built environment. Precast supply chain, as a vital connection between construction sites and off-site plants, is the focus of many recent studies. While these studies have greatly advanced precast supply chain management (PSCM), a critical analysis to summarize the recent research, to identify research gaps, and to inform future research needs is largely missing in the field of precast supply chain management. The overarching goal of this paper is to create a taxonomy to properly classify existing studies in precast supply chain management so as to reveal research gaps and suggest future research opportunities. The specific tasks in this review project include: (1) conducting bibliographic categorizations with regard to journals, years and geographic distributions of publications; (2) identifying the citation correlations and formulating the keyword connection networks; (3) classifying the literature based on research topics and highlighting the state of the art pertaining to each subtopic. The in-depth analysis shows that the studies on precast production are dominant in the PSCM domain. The major research approaches used in existing studies include the genetic algorithm, simulation, RFID (Radio Frequency Identification), and BIM (Building Information Modeling). At last, the possible future research focuses are highlighted, such as dynamic disturbances management, smart precast supply chain, coordination among participants, simultaneously optimizing scheduling and resource allocation. • Conducting bibliographic categorizations with regard to journals, years and geographic distributions of publications. • Presenting the citation correlations of crucial publications and keyword connection networks. • The mainstream research is classified into four thrust areas and the state of the art pertaining to each subtopic is summarized. • The research gaps and possible future research focuses are highlighted [ABSTRACT FROM AUTHOR]

A novel pocket connection was put forward to be utilized in both ends of a precast bridge column to connect cap beam and foundation, respectively. The pocket connection adopted noncontact lap-spliced bars and ultra-high performance concrete (UHPC) grout. One 1:2.5 scale specimen was fabricated and tested to investigate the seismic performance of the precast bridge column with the proposed pocket connections. Based on OpenSees platform, a verified finite element model was utilized to simulate cyclic behavior of a monolithic reinforced concrete companion. The comparison was carried out to evaluate the precast bridge column in a comprehensive way. The results show that drift capacities of the two bridge columns are up to 5% and controlled by lateral force degradation. The lapped length of five times diameter is feasible when UHPC grout is used for longitudinal bars with a diameter no more than 32 mm. For the precast bridge column, the joint opening between column and foundation contributes over 30% to total lateral displacement and traditional equivalent plastic hinge model may be not suitable. With drift ratio over 1.5%, the precast specimen has larger secant stiffness than that of the monolithic companion, owing to the shorter shear length of the precast specimen caused by moving up of the actual plastic hinge region. The precast and monolithic bridge columns have good energy dissipation capacity, and the maximum damping ratios reach up to 19.8% and 22.6% at 5% drift ratio, respectively. The precast specimen has 18.8% less residual drift ratio at 5% drift ratio than the monolithic companion. [ABSTRACT FROM AUTHOR]

An assembling method of precast shear walls was previously proposed using steel–concrete composite bolted connectors. To further investigate the effectiveness and mechanical behavior of the proposed composite connector, 11 specimens were fabricated and tested under monotonic tensile loading. The test results provided comprehensive data (e.g. load, deformation, failure mode) on the effects of variation in the thickness of steel cap plate, concrete strength, bolt tension, and bolt diameter. Two typical failure modes were observed in the test: bearing failure and bolt shear failure. Finally, the equations for calculating the ultimate strength and yield strength of steel–concrete composite bolted connector are proposed in this article by reference to those of conventional bolted connection. The proposed calculations are demonstrated to be accurate enough through verification with the experimental data. [ABSTRACT FROM AUTHOR]

With the rising demand of clean wind energy, concrete and hybrid segmental towers have been frequently constructed in recent years. In the area of very high towers, they have replaced the traditional steel towers due to better transportability and economy. However, the joints between adjacent segments have led to questions, which are not satisfactorily resolved by current models or calculation approaches. The transmission of shear forces and torsion moments take place exclusively inside the so‐called horizontal dry joint. Current calculations are carried out according to the torsion theories of Bredt for ring cross sections and Saint‐Venant for open thin‐walled cross sections. However, these approaches, which are used to describe the bearing and deformation behavior of such joints, are insufficient. Depending on the loading situation, this leads to both unsafe results and unused strength. In this paper, an actual wind tower construction with a ring cross section is thoroughly analyzed based on current theory. Additionally, numerical simulations are carried out. The torsion resistance of segmental tower structures is investigated in detail. The inaccuracy of current theories is demonstrated. [ABSTRACT FROM AUTHOR]

Design and construction of a railway bridge in reinforced UHPFRC – World's first UHPFRC bridge on a main railway line On November 11, 2017, the world's first railway bridge built in reinforced UHPFRC on a main railway line lane was put in service. The building project of the Swiss Federal Railways was realized within a replacement project of a double‐lane railway bridge of short span at Sempach in the Canton of Lucerne, Switzerland. UHPFRC is a novel cementitious fibre‐reinforced composite material of high strength and durability that provides ideal properties for application to structures of transportation infrastructure. In addition to lower life cycle costs, the modular construction method including a high prefabrication degree allows for shorter construction time and thus reduced service restrictions. The UHPFRC structure with a span of 6.0 m was equipped with a monitoring system to capture the structural behavior due to train crossings. First results of the measurements confirm the expected values that lie significantly below the calculated values. This article describes the design, dimensioning, execution and monitoring of this novel bridge structure. [ABSTRACT FROM AUTHOR]

Torsional behavior of a segment tower with an alternative joint design Based on the most commonly constructed segment wind turbine towers at present, a further developed design of joints is described in this article. The dry joint which works without balancing layer of epoxy or cement mortar has been applied to wind turbine towers in the horizontal direction for many years. It should also be applied in the vertical direction. The evenness in the joint will be assured with the help of a high‐precision milling machine. Therefore, the compactness and force transmission of the construction can be guaranteed. However, a decrease of structural resistance is still observed through numerical simulation. By changing the integral cross section to an open half‐ring segment, the weak part can be easily pointed out in the structure design itself and also by current design approaches. There are currently no suitable theories or regulations for this kind of structural design. [ABSTRACT FROM AUTHOR]

A series of non-linear analyses is presented in this article investigating the differences in mechanical characteristics of the common concrete shear wall, the concrete shear wall with concealed vertical slits, and the concrete cavity shear wall under monotonic loading. The numerical analyses define monotonic capacity curves and ductility. The results indicate that reasonable matching can be achieved in stiffness, capacity, and ductility, and non-linear behavior can be improved in cavity shear wall by changing the parameters of the cavity. A theoretical model of cavity shear wall structure is proposed to estimate the lateral displacement curve and the equivalent lateral stiffness. The effectiveness of the theoretical formula was validated by the results from numerical models with different parameters. The influence of cavity parameters on equivalent lateral stiffness is discussed, and the effect of different parameters is investigated. The results indicate that equivalent lateral stiffness of the shear wall can be reduced by increasing the length or the thickness of the cavity; the cavity’s effect on squat shear walls is significantly larger than that on slender walls. [ABSTRACT FROM AUTHOR]

Despite a great deal of research into precast production scheduling published in academic journals worldwide, little attention has been given to environmental performance related to precast construction transportation and assembly scheduling problems. To address this issue, this paper studies the Just-in-Time (JIT) strategy for supply chain management of precast construction while considering time-dependent transportation time and on-site assembly time. There are two main contributions of our work. First, our analysis expands the current batch-scheduling model of minimizing earliness/tardiness penalties, by incorporating environmental impact considering the time-dependent transportation time and economic impact of resources wasted by waiting for on-site assembly. Second, we quantify the economic and environmental performance using our research objective, consisting of earliness/tardiness penalties, an additional transportation time penalty, and a resource waste penalty. The optimal results show that, compared with the supplier's intuitive minimax optimization with deliveries on the earliest due date, there is an average 10.7% reduction of the objective value of a one-day assembly task by our proposed method. The results also show that the objective of achieving additional environmental performance conflicts with that of obtaining economic performance. However, sensitivity analysis further shows it is not always true to consider only additional environmental performance for the suppliers to achieve ‘green’ value. For a sustainable business, the customer's service-JIT delivery should also be considered. Thus, when the policy makers assign importance weights to different objectives, they should fully consider both the economic and environmental impacts. The research contributes to batch delivery theory by expanding the approach to a time-dependent delivery model by considering both the economic and environmental effects. The method developed is of practical value for precast building projects to help in the successful implementation of sustainable development. [ABSTRACT FROM AUTHOR]

To avoid iterative calculation, an explicit analytical model was developed for the deformation capacity of an unbonded post-tensioned precast segmental rocking hollow pier and divided into three statuses: decompression status, yield status and large deformation status. The pier was regarded as an equivalent reinforced concrete monolithic pier at the decompression status, and the compression zone height at the base section was computed explicitly to make deformation calculation non-iterative at the other two statuses. A verified fiber model based on the OpenSees platform was proposed. The proposed deformation capacity model was validated with existing cyclic loading tests and the verified fiber model. A parametric study was conducted to determine the effects of the main design parameters on four coefficients of the idealized flag-shaped hysteretic model based on the proposed deformation capacity model. New formulas were proposed to determine the four coefficients through regression analysis. The flag-shaped hysteretic model with the coefficients determined by the proposed formulas was validated with cyclic loading tests and dynamic history analysis based on the fiber model. The results of this research show that the proposed model for deformation capacity may be simplified into two statuses, and it can serve as a tool to provide loading-deformation curves that have good agreement with experiments and the fiber model. The flag-shaped hysteretic model with the proposed coefficients can accurately predict the maximum displacement response and conservatively predict the dissipation energy capacity for the rocking pier under a strong earthquake shock. [ABSTRACT FROM AUTHOR]

The advancement of prefabricated buildings has become a prominent trend in the construction sector. Disturbance events as a significant obstacle to the production of prefabricated components, restricting the realization of green, efficient, and sustainable advantages in prefabricated construction. This study examines how different disturbance events can affect precast production rescheduling and the selection of rescheduling schemes based on different carbon emissions scenarios. To attain dynamic disruption management while simultaneously considering carbon emissions in production, a three-layer scheduling disruption management model which includes two production lines is established, which seeks to minimize the maximum completion time, the earliness and tardiness penalty, and carbon emissions. Then an improved non-dominated sorting genetic optimization algorithm is devised to tackle the proposed model. Furthermore, two scenarios, specifically increased PC production types and advanced PC due dates, are explored to accurately depict real-life production environments. A case study is subsequently utilized to validate the efficacy of the proposed model. The disruption management rescheduling model result in cost savings of 16.5% and 50%, as well as carbon emissions reductions of 1.5% and 9.1%, respectively. The empirical findings from the case study reveal that both the developed model and the refined algorithm are practical and efficient. This research contributes to the development of rescheduling schemes for prefab manufacturers, addressing both customer satisfaction and demands for green production, ultimately improving overall project performance. [ABSTRACT FROM AUTHOR]

• Precast concrete T-beams with a cast-in-place slab on top are tested in shear. • The contribution of the slab to shear strength is experimentally analysed. • The shear strength mechanisms of monolithic and composite T-shaped beams are analysed. • The tangential stresses at the interface and the interface shear strength are key. • Current codes' shear formulations underestimate composite elements' shear strength. Precast concrete T-beams with a cast-in-place slab on top are structural elements that are often employed in composite construction. Despite their widespread use, some aspects of their structural behaviour upon shear forces have not yet been studied in depth. Six composite specimens with different T-shaped cross-sections and concrete qualities, and with web reinforcement, were tested to analyse the shear transfer mechanisms and to assess the contribution of the cast-in-place slab to shear strength. The shear strength mechanisms deriving from experimental observations and measurements are provided. This study indicates that: placing a concrete cast-in-place slab on top of a prefabricated T-beam increases its shear strength; interface shear strength plays an essential role in concrete composite elements' vertical shear strength; widening the cast-in-place slab width does not increase shear strength in this test programme specimens; the compressive strength of the precast beam's concrete significantly influences composite beams' shear resistances. The ACI 318-19 formulation best captures the influence of concrete strength on shear strength of the three formulations considered (EC2, MC-10 (Level III) and ACI 318-19). However, all of them tend to underestimate shear strengths compared to the experimental results. [ABSTRACT FROM AUTHOR]

Recent research has shown that reinforced concrete (RC) beams with concrete-to-concrete casting interfaces where plastic hinges are likely to develop, may experience reduced ductility in comparison to similar structural elements casted at once, due to a potential shear slippage along the casting interfaces. Although of relevant importance for both precast and cast in situ RC structures, this problem is still not addressed in current codes and standards, which limit the safety check of casting interfaces to the verification of their strength based on improved expressions of the “ shear friction theory ”, the latter proposed in the 60’s. However, recent research has shown that friction strength of casting interfaces depends on interface width opening, and it is significantly reduced after the yield of the bending reinforcement. During the formation of plastic hinges, shear stresses run preferentially across the compressed zones of the interfaces, reducing their strength, and ultimately the specimens’ ductility. In this paper, different and alternative details for interfaces are proposed to improve global behaviour, and in particular, ductility of RC beams with casting interfaces located on plastic hinges regions. An experimental campaign was carried out to study the effect of: (i) epoxy and latex based adhesion promoters’ usage between castings; (ii) web reinforcement; (iii) geometry of interfaces; (iv) and shear level. Results show that both epoxy and latex based adhesion promoters, currently used in construction, hardly improve the tensile strength of casting interfaces, to a point that the interface presence has negligible impact on the cracking pattern. A much better result was observed from the use of a web reinforcement crossing the interface perpendicularly. Although this solution revealed itself also incapable to avoid preferential cracking along the interfaces, it proved to be efficient in limiting shear slippages. The adoption of inclined interfaces either perpendicular or parallel to the expected direction of shear cracks proved also to be an efficient solution. Finally, the likelihood of experiencing a shear slippage along the interface is strongly dependent on the existing shear level after the formation of a plastic hinge. [ABSTRACT FROM AUTHOR]

The manufacture, transportation and on-site assembly sectors of precast construction projects are often considered separately and managed by rule of thumb, causing an inefficient use of resources and postponed delivery. This study views these sectors as a whole from the perspective of a single machine batch-scheduling problem. A dynamic programming algorithm, which aims to search for solutions that entail maximum production efficiency, was developed accordingly with the constraints of changeover costs and production deadlines. We tested the method’s ability by processing as many products as possible simultaneously using real data collected from a precast factory in a simulation and compared the effect with a previous study. We found that our method possesses great potential to improve the efficiency of precast production. [ABSTRACT FROM AUTHOR]

Production scheduling plays a key role in the prefabricated construction productivity and on-time delivery of precast components (PCs). However, the processes before and after the production of PCs were ignored in previous scheduling studies. These operations account for a large proportion of the PCs' processing time in practice. To ensure the accurate calculation of PC's completion time and its on-time delivery, this study integrates the mold manufacturing, PC storing, and transportation processes to modify the traditional productionscheduling model from the perspective of the whole PC supply chain. Further, the three scenarios of daytime, night, and all-day transportation are analyzed to conform to the practice. Based on the genetic algorithm, two case studies are conducted to test the validity of the proposed scheduling model. The modified schedule could achieve 17.7, 35.7, and 15.4% cost savings in the three scenarios, respectively. The methodology will enhance the feasible production scheduling and promote on-time delivery of PCs. [ABSTRACT FROM AUTHOR]

This study serves as a practical model for optimizing production planning, allocation of precast component storage, and transportation sites as well as for making timely adjustments for contracted projects. To ensure that the structure of the research model is reasonable and matches actual applications, the study uses a field survey to directly observe the largest precast concrete plants in Taiwan for a period of 6 months, followed by in-depth interviews with experts involved with the planning, design, installation, and manufacturing for precast projects. The mathematical model is then established and evaluated using the data containing over 90% of national production in Taiwan. The results show that the tested corporate profits increase by an impressive 38.4% and performance is significantly increased by 97.75%. The proposed model can not only make up for oversights in human decision-making but improve the decision-making process boosting corporate competitiveness. [ABSTRACT FROM AUTHOR]

The shear strength of concrete-to-concrete interfaces subjected to either shear or normal forces perpendicular to the interface, or to a combination of both, has been predicted using the “ shear-friction theory ” developed in the 60’s for connections for the precast construction. The “ shear-friction theory ” has been developed considering shear failure as pure slippage, and not in combination with a tension crack, and it has been adopted in most design codes worldwide. Although several improvements have been made to the original theory in the last 50 years, few have addressed the behaviour of interfaces subjected to a combination of shear and bending moment, where a shear slippage may occur along a tension crack and a compression zone. This is a relevant issue for the design of both cast-in-place and precast reinforced concrete structures. This paper, presents an experimental work addressed to the study of the behaviour of concrete-to-concrete interfaces subjected to a combination of shear and bending moment. The influence of the interface on the global behaviour and shear and bending strengths of a beam specimen are addressed, as well as the application of the design expressions. Results show that the load transfer capacity across the interface is reduced due to the bending moment crack opening, but it has no influence on the shear and the bending strengths of the beam specimen. However, the bending ductility of the latter is partially reduced due to a shear slippage occurred after the formation of a plastic hinge, and the collapse of the compression zone. It was not possible to evaluate the accuracy of the design expressions to predict the interface maximum friction strength. However, the general application of these expressions to this situation is doubtful, as they are incapable to predict the strength deterioration occurred after the yielding of the longitudinal reinforcement. [ABSTRACT FROM AUTHOR]

Resource scheduling of construction proposals allows project managers to assess resource requirements, provide costs and analyse potential delays. The Manufacturing, transportation and Assembly (MtA) sectors of precast construction projects are strongly linked, but considered separately during the scheduling phase. However, it is important to evaluate the cost and time impacts of consequential decisions from manufacturing up to assembly. In this paper, a multi-objective Genetic Algorithm-based (GA-based) searching technique is proposed to solve unified MtA resource scheduling problems (which are equivalent to extended Flexible Job Shop Scheduling Problems). To the best of the authors' knowledge, this is the first time that a GA-based optimisation approach is applied to a holistic MtA problem with the aim of minimising time and cost while maximising safety. The model is evaluated and compared to other exact and non-exact models using instances from the literature and scenarios inspired from real precast constructions. [ABSTRACT FROM AUTHOR]

The seismic performance of unbonded posttensioned (PT) precast segmental bridge columns (PSBCs) with circular sections was investigated. Two precast segmental columns with/without energy dissipation (ED) bars were tested under quasi-static cyclic loading. Their damage patterns and hysteretic curves were compared. Three single-degree-of-freedom hysteretic models were formulated with the key parameters identified from the tests. Cyclic loading analyses of the two tested specimens were conducted using these hysteretic models. Time history analyses were also conducted utilizing the proposed three hysteretic models to observe their applicability in modeling the dynamic responses of PSBCs. Finally, parametric analyses of PSBCs were performed under the excitation of an ensemble of 20 history ground motions to study the influences of relative yield force, elastic period, and energy dissipation coefficient on the earthquake responses of displacement ductility demand, maximum absolute acceleration, and maximum absorbed energy. [ABSTRACT FROM AUTHOR]