Search Results (12)

To investigate the initial rotational stiffness and ultimate moment of fully bolted connections in panelized steel modular structures, a finite element analysis was carried out on 20 joint models. High-fidelity models were developed using ABAQUS, and their accuracy was confirmed through comparison with experimental tests. A parametric study was performed to systematically evaluate the effects of the column wall thickness in the core zone, internal diaphragm configurations, angle steel thickness, and stiffener layouts on the joint stiffness and ultimate strength, leading to practical optimization suggestions. Additionally, a mechanical model and a corresponding formula for predicting the initial rotational stiffness of the joints were proposed based on the component method in Eurocode EC3. The model was validated against the finite element results, showing good reliability. Three failure modes were identified as follows: buckling deformation of the beam flange, buckling deformation of the column flange, and deformation of the joint panel zone. In joints with a weak core zone, both the use of internal diaphragms and increased column wall thickness effectively improved the initial rotational stiffness and ultimate bearing capacity. For joints with weak angle steel connections, adding stiffeners or increasing the limb thickness significantly enhanced both the stiffness and capacity. The diameter of bolts in the endplate-to-column flange connection was found to have a considerable effect on the initial rotational stiffness, but minimal impact on the ultimate strength. This study offers a theoretical foundation for the engineering application of panelized steel modular structural joints. Full article

The construction of buildings using shipping containers (SCs) is a way to extend their useful life. They are constructed by modifying the structure, thermal, and acoustic conditioning by improving the envelope and creating openings for lighting and ventilation purposes. This study explores the architectural adaptation of SCs to sustainable residential housing, focusing on structural, thermal, and acoustic performance. The project centers on a case study in Madrid, Spain, transforming four containers into a semi-detached, multilevel dwelling. The design emphasizes modular coordination, spatial flexibility, and structural reinforcement. The retrofit process includes the integration of thermal insulation systems in the ventilated façades and sandwich roof panels to counteract steel’s high thermal conductivity, enhancing energy efficiency. The acoustic performance of the container-based dwelling was assessed through in situ measurements of façade airborne sound insulation and floor impact noisedemonstrating compliance with building code requirements by means of laminated glazing, sealed joints, and floating floors. This represents a novel contribution, given the scarcity of experimental acoustic data for residential buildings made from shipping containers. Results confirm that despite the structure’s low surface mass, appropriate design strategies can achieve the required sound insulation levels, supporting the viability of this lightweight modular construction system. Structural calculations verify the building’s load-bearing capacity post-modification. Overall, the findings support container architecture as a viable and eco-efficient alternative to conventional construction, while highlighting critical design considerations such as thermal performance, sound attenuation, and load redistribution. The results offer valuable data for designers working with container-based systems and contribute to a strategic methodology for the sustainable refurbishment of modular housing. Full article

A new concept of a 3D volumetric module, made up of six plane stiffened self-compacting fiber-reinforced concrete (SFRC) panels, is here studied. Experimental campaigns are carried out on SFRC material and on the thin-slab structures used for this modular concept. The high volume of steel fibers (80 kg/m³) used in the formulation of this concrete allow a positive strain hardening to be obtained in the post-cracking regime observed on the bending characterization tests. The high mechanical material characteristics, obtained both in tension and compression, allow a significant decrease in the module slabs’ thickness. The tests carried out on the 7 cm thick slab demonstrate a high load-bearing capacity and ductility under bending loading; this is also the case for shear loading configuration, although without any shear reinforcements. Numerical simulations of the material mechanical tests were conducted using Abaqus code; the results corroborate the experimental findings. Then, simulations were also conducted at the structural level, mainly to evaluate the behavior and the bearing capacity of the thin 3D module stiffened slabs. Finally, knowing that the concrete module truck transport can be a weak point, the decelerations induced during transportation were characterized and the integrity of the largest 3D module was demonstrated. Full article

Hybrid building construction, in which the steel frame is filled with modular panels made of wood, is a relatively new technical solution. This type of structure allows the integration of large window surfaces. The aim of this study is to indicate the optimal glazing system, taking into account energy consumption, thermal comfort and economic indicators. A house made using new hybrid technology with an area of 152.4 m², located in Bialystok (Northeastern Poland) and in Kiruna (Northern Sweden), was selected as the reference object. Energy simulations of this building were performed with DesignBuilder v. 6.1.8.021 software. Due to the large format of the glazing, the assessment of the thermal environment was performed using the PMV index. An economic analysis aimed at selecting the optimal type of glazing was carried out. It was based on the most commonly used indicators such as LCC, NPV and IRR. The results of this study indicated that the selection of triple-glazed windows in the reference house reduced energy demand by over 22% for Bialystok and about 24% for Kiruna compared to double-glazed windows. Even greater effects can be achieved by using quadruple-glazed windows, as they provide energy savings of 36% and 39%, respectively, for these locations. The results of the analysis performed for a 2% increase in energy prices showed that triple and quadruple windows had a similar LCC value when the discount rate was lower than 2.5% for the Bialystok site. Quadruple-glazed windows were the best option for the Kiruna site when the discount rate was less than 5%. This research study found that, assuming a stable financial situation and a small increase in energy prices, it is recommended to use triple-glazed windows in the climate of Northeastern Poland. In more severe weather conditions, for example those characteristic of the area of Northern Sweden, quadruple-glazed windows are recommended. Full article

Single-sided formwork supporting systems (SFSSs) play a crucial role in the urban construction of retaining walls using cast-in-place concrete. By supporting the formwork from one side, an SFSS can minimize its spatial footprint, enabling its closer placement to boundary lines without compromising structural integrity. However, existing SFSS designs struggle to achieve a balance between mechanical performance and lightweight construction. To address these limitations, an innovative instrumented SFSS was proposed. It is composed of a panel structure made of a panel, vertical braces, and cross braces and a supporting structure comprising an L-shaped frame, steel tubes, and anchor bolts. These components are conducive to modular manufacturing, lightweight installation, and convenient connections. To facilitate the optimal design of this instrumented SFSS, a physics-constrained generative adversarial network (PC-GAN) approach was proposed. This approach incorporates three objective functions: minimizing material usage, adhering to deformation criteria, and ensuring structural safety. An example application is presented to demonstrate the superiority of the instrumented SFSS and validate the proposed PC-GAN approach. The instrumented SFSS enables individual components to be easily and rapidly prefabricated, assembled, and disassembled, requiring only two workers for installation or removal without the need for additional hoisting equipment. The optimized instrumented SFSS, designed using the PC-GAN approach, achieves comparable deformation performance (from 2.49 mm to 2.48 mm in maxima) and slightly improved component stress levels (from 97 MPa to 115 MPa in maxima) while reducing the total weight by 20.85%, through optimizing panel thickness, the dimensions and spacings of vertical and lateral braces, and the spacings of steel tubes. This optimized design of the instrumented SFSS using PC-GAN shows better performance than the current scheme, combining significant weight reduction with enhanced mechanical efficiency. Full article

Stainless steel core plates (SSCPs) show great potential for modular construction due to their superiority of excellent mechanical properties, light weight, and low cost over traditional concrete and honeycomb structures. During the brazing process of SSCP joints which connect the skin panel and core tubes, it is difficult to keep an even heat flow of inert gas in the vast furnace, which can lead to partially missing solder defects in brazing joints. Pulsed eddy current imaging (PECI) has demonstrated feasibility for detecting missing solder defects, but various factors including lift-off variation and image blurring can deteriorate the quality of C-scan images, resulting in inaccurate evaluation of the actual state of the brazed joints. In this study, a differential pulsed eddy current testing (PECT) probe is designed to reduce the lift-off noise of PECT signals, and a mask-based image segmentation and thinning method is proposed to eliminate the blurring effect of C-scan images. The structure of the designed probe was optimized based on finite element simulation and the positive peak of the PECT signal was selected as the signal feature. Experiments with the aid of a scanning device are then carried out to image the interrogated regions of the SSCP specimen. The peak values of the signals were collected in a matrix to generate images of the scanned brazing joints. Results show that lift-off noise is significantly reduced by using the differential probe. Image blurring caused by the convolution effect of the probe’s point spread function with the imaging object was eliminated using a mask-based image segmentation and thinning method. The restored C-scan images enhance the sharpness of the profiles of the brazing joints and the opening in the images accurately reflect the missing solder of the brazed joints. Full article

Modular integrated construction (MiC) is a new type of assembled building structure system that consists of prefabricated concrete modules connected using post-cast concrete. To reduce material consumption and realize casting without supporting molds, thin and lightweight concrete formworks (MiC formworks) with a thickness of 30 mm are installed as part of the shear wall. Due to the thinness, concrete pouring tends to cause MiC formwork cracking, mold rising, and other problems. Its stress performance and damage mechanism are not clear. For this reason, three groups of MiC formworks with different material composition types are designed. The static load test is carried out in a graded partition loading mode, and parametric analysis is combined with numerical simulation to systematically study the influence of different material components on the mechanical properties of MiC formworks. The results show that the front cracks of the MiC formworks are mainly distributed under the truss tendons, and the back cracks are mainly distributed in the span position of the adjacent truss tendons. These cracks both occur along the span direction of the MiC formworks. Increasing the concrete strength has a significant effect on improving the load-bearing capacity of MiC formworks, while incorporating steel fibers can significantly improve its deformation and crack resistance. Parametric analysis showed that the steel fiber admixture exhibited limited improvements in the cracking resistance of the panels as the concrete matrix grade increased. The research results provide a practical basis for optimizing the production process of MiC formworks. Full article

Modular steel buildings show high assembly degree and fast installation speed. The inter-module connection (IMC) is one of the key technologies that restrict the robustness of modular steel buildings. An innovative IMC with a cross-shaped plug-in connector is proposed, and the connection consists of end plates of columns, the cross-shaped plug-in connector, bolts, cover plates, and one-side bolts. The proposed IMC is easily constructed, and the cross-shaped plug-in connector can improve the shear resistance of the core area. The mechanical model of the proposed IMC is presented, and the panel zone volume modified factor and initial rotational stiffness modified factor are proposed for calculating the shear capacity of the panel zone and the initial rotational stiffness. Numerical simulation was conducted considering the influences of axial compression ratios, sections of beams and columns, and the thickness of the tenon plate of the connector. The bearing capacity of the proposed IMC was analyzed, and the values of the two factors mentioned above were calculated, and their regression formulas are presented. The results show that the sections of beams and columns and the axial compression ratios show great influences on the bearing capacity of the proposed IMC, while the thickness of the tenon of the cross-shaped plug-in connector shows almost no effect. In addition, the sections of beams and columns show great influences on the shear capacity of the panel zone, as well as the initial rotational stiffness of the proposed IMC, while the thickness of the tenon of the cross-shaped plug-in connector and the axial compression ratios show little effect and almost no effect, respectively. Furthermore, the bending moment limit of the beam end of the proposed IMC is suggested to be 0.6 times the resistance bending moment, and the proposed IMC is considered to be a rigid connection or inclined to a rigid connection The proposed IMC has good mechanical performance, and design recommendations are presented. Full article

Stainless steel core panel is a novel structure for fast modular building, but its brazing foils are susceptible to defects due to the difficulty of precisely controlling the brazing process. An automated, nondestructive testing technique is highly desirable for quick inspection of the brazing defects buried in the stainless-steel core panel. In this paper, pulsed eddy current testing (PECT) was employed to inspect local incomplete brazing defects. Finite element simulation and experiment verification were conducted to investigate the feasibility and effectiveness of the proposed method. The peak value of the PECT signal was found to be sensitive to the presence of the defect. With the aid of an industrial robotic arm, line and two-dimensional scans were performed of the PECT probe above the panel specimen. The prefabricated incomplete brazing foil was successfully imaged as a notched ring, whose opening coincides with the physical length of the missing brazing. The proposed method shows potential to serve as an effective tool for in-line or off-line automated nondestructive testing of the brazing defects in stainless steel core panels. Full article

A newly developed innovative steel–geopolymer concrete composite floor slab for use in modular construction is investigated in this study. We present experimental results on the flexural behaviour of eight modular sandwich composite floor slabs with different configurations containing self-compacting geopolymer concrete (SCGC) as infill and Basalt FRP (BFRP) bars as reinforcement. The use of sustainable infill material such as SCGC and non-corrosive BFRP in the proposed composite floor slabs is beneficial from the perspective of environmental sustainability. This study also compares the performance of these composite floor slabs against their hollow counterparts. The overlap between the cells in multi-cell panels acts as additional partitioning walls. The infill material offers the sandwich composite floor slabs significant advantages by improving their load-carrying capacity. A critical analysis of the composite floor slabs for load displacement, failure modes, and strain behaviour is also conducted. The study concludes that the sandwich panels with multiple smaller cells and infill materials exhibit a sound structural performance, reporting a 6–8 times higher load-carrying capacity than their hollow counterparts. A comparison of hollow and infilled panels shows that the infill sandwich panels are suitable as structural slabs. At the same time, the former is more suitable for temporary formworks, shelter, and pedestrian platform applications. Full article

Lightweight modular construction has become an increasing need to meet the housing requirements around the world today. The benefits of modular construction ranging from rapid production, consistency in quality, sustainability, and ease of use have widened the scope for the construction of residential, commercial, and even emergency preparedness facilities. This study introduces novel floor panels that can be flat-packed and built into modular housing components on-site with minimal labour and assistance. The flooring system uses hollow cellular panels made of various configurations of trapezoidal steel sheets. The structural performance of three different configurations of these hollow flooring systems as a modular component is presented in this study by analysing the failure modes, load-displacement parameters, and strain behaviour. The study confirms significant advantages of the proposed hollow floor systems, with multi-cells reporting higher load-carrying capacity. The hollow flooring system performed well in terms of structural performance and ease in fabrication as opposed to the conventional formworks and commercial temporary flooring systems. The proposed flooring system promises efficient application as working platforms or formworks in temporary infrastructural facilities and emergency construction activities. Full article

The modal properties of modular structures, such as their natural frequencies, damping ratios and mode shapes, are different than those of conventional structures, mainly due to different structural systems being used for assembling prefabricated modular units onsite. To study the dynamic characteristics of modular systems and define a dynamic model, both the modal properties of the individual units and their connections need to be considered. This study is focused on the former aspect. A full-scale prefabricated volumetric steel module was experimentally tested using operational modal analysis technique under pure ambient vibrations and randomly generated artificial hammer impacts. It was tested in different situations: [a] bare (frame only) condition, and [b] infilled condition with different configurations of gypsum and cement-boards light-steel framed composite walls. The coupled module-wall system was instrumented with sensitive accelerometers, and its pure and free vibration responses were synchronously recorded through a data acquisition system. The main dynamic characteristics of the module were extracted using output-only algorithms, and the effects of the presence of infill wall panels and their material are discussed. Then, the module’s numerical micromodel for bare and infilled states is generated and calibrated against experimental results. Finally, an equivalent linear strut macro-model is proposed based on the calibrated data. The contribution of this study is assessing the effects of different infill wall materials on the dynamic characteristics of modular steel units, and proposing simple models for macro-analysis of infilled module assemblies. Full article