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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.

In order to accurately monitor graft immunology, we have developed a method for performing intestine and abdominal wall transplantation heterotopically in miniature swine. The procedure consisted of simultaneous segmental terminal ileum and full‐thickness abdominal wall transplantation in Lanyu miniature swine, with the intestinal and the abdominal wall grafts being placed on the recipient's bilateral rear flank. Five transplantations were technically successful. One animal died on the first post‐transplant day due to anesthesia‐related issues, three abdominal wall and four intestinal grafts survived, while one abdominal wall graft failed due to vascular thrombosis. Acute cellular rejection (ACR) of the intestinal graft could occur preceding, simultaneously with or following ACR of the abdominal wall graft. Our experimental model demonstrates the technical feasibility of heterotopic intestine and abdominal wall transplantation in miniature swine without grafting in gastrointestinal continuity. This model could be suitable for further studies of graft immunology.

Cell wall disassembly occurs naturally in plants by the action of several glycosyl-hydrolases during different developmental processes such as lysigenous and constitutive aerenchyma formation in sugarcane roots. Wall degradation has been reported in aerenchyma development in different species, but little is known about the action of glycosyl-hydrolases in this process. In this work, gene expression, protein levels and enzymatic activity of cell wall hydrolases were assessed. Since aerenchyma formation is constitutive in sugarcane roots, they were assessed in segments corresponding to the first 5 cm from the root tip where aerenchyma develops. Our results indicate that the wall degradation starts with a partial attack on pectins (by acetyl esterases, endopolygalacturonases, β-galactosidases and α-arabinofuranosidases) followed by the action of β-glucan-/callose-hydrolysing enzymes. At the same time, there are modifications in arabinoxylan (by α-arabinofuranosidases), xyloglucan (by XTH), xyloglucan-cellulose interactions (by expansins) and partial hydrolysis of cellulose. Saccharification revealed that access to the cell wall varies among segments, consistent with an increase in recalcitrance and composite formation during aerenchyma development. Our findings corroborate the hypothesis that hydrolases are synchronically synthesized, leading to cell wall modifications that are modulated by the fine structure of cell wall polymers during aerenchyma formation in the cortex of sugarcane roots.

This experimental study evaluates the seismic performance of two vertical connection types in a novel precast grid composite wall structure (PGCWS): a steel bar anchorage (SW-1) and a mortar cushion connection (SW-2). Quasi-static cyclic tests were conducted on 1:2-scale specimens to assess failure modes, hysteretic behavior, stiffness degradation, and energy dissipation capacity. The results indicate that SW-1 maintains structural integrity and facilitates controlled damage distribution, demonstrating ductile failure with an ultimate drift of 1/45.5, stable hysteresis loops, and high energy dissipation (20,400 kN mm). In contrast, SW-2 exhibited premature interface slip, resulting in brittle failure characterized by significant hysteresis pinching, rapid stiffness loss, and substantially lower energy dissipation (11,400 kN mm), with a limited ultimate drift of 1/66.5. Based on these findings, performance-based design recommendations are proposed. The steel bar anchorage is advised for mid- to high-rise buildings in high-seismic regions due to its robustness and energy dissipation capability. The mortar cushion connection may be suitable for low- to mid-rise structures where construction efficiency is emphasized, provided that inter-story drift is strictly controlled. This research offers essential experimental evidence to support the practical implementation of PGCWS.

Precast concrete sandwich panels (PCSPs) are utilized for the external cladding of structures (i.e., residential, and commercial) due to their high thermal efficiency and adequate composite action that resist applied loads. PCSPs are composed of an insulating layer with high thermal resistance that is mechanically connected to the concrete. In the recent decades, PCSPs have been a viable alternative for the fast deployment of structures due to the low fabrication and maintenance cost. Furthermore, the construction of light and thin concrete wythes that can transfer and resist shear loads has been achieved with the utilization of high-performance cementitious composites. As a result, engineers prefer PCSPs for building construction. PCSP design and use have been examined to guarantee that a building is energy efficient, has structural integrity, is sustainable, is comfortable, and is safe. Hence, this paper reviews the expanding knowledge regarding the current development of the mechanical and thermal properties of the PCSPs components; subsequently, future potential research directions are suggested.

To explore the optimization seismic design of frame-multi-ribbed composite wall structure, firstly the finite element model of a six story frame-multi-ribbed composite wall structure is established based on the software of SAP2000. Secondly the critical design parameters of multi story frame-multi-ribbed composite wall structure under seismic action are analysised using finite element analysis software. Finally the seismic response of the structure under different rib combinations and the optimal arrangement rule of the structure are studied. The results reveals that the lateral stiffness of the structure cannot be effectively improved by increasing the number of rib grids of the multi ribbed composite wall. The results can provide a theoretical basis for the design of the multi story frame-multi-ribbed composite wall structure in the medium and high earthquake intensity area.

Polypropylene fibers (PPFs), characterized by their low density, cost-effectiveness, and superior corrosion resistance, can be effectively incorporated into concrete to enhance the impact resistance of wall panels. This study introduces an innovative composite wall panel utilizing polypropylene fiber-reinforced concrete (PFRC) as the core material. Initially, an experimental investigation into the mechanical properties of PFRC was conducted, and based on these results, a constitutive model for PFRC was established. Subsequently, the impact-induced mechanical behavior of the innovative composite wall panel was investigated through finite element simulations employing ABAQUS, version 2020, software. The findings indicate that polypropylene fibers significantly improve both the compressive strength and ductility of concrete, with an optimal coarse fiber content of 1%. The inclusion of glass fiber grids and polypropylene fibers reduced the number of cracks and the overall deformation of the composite wall panel. The integration of glass fiber grids coupled with fiber reinforcement resulted in 7.2% and 27.8% enhancements in impact resistance, respectively. Parametric studies demonstrated that greater concrete panel thickness effectively diminishes post-impact peak and residual displacements in composite wall systems. Furthermore, the impact resistance was found to be weaker at the panel edges and stronger at a quarter of the panel height.

The multi ribbed composite wall structure is also known as the multi ribbed wall panel light frame structure. This structure is suitable for housing construction in the residential field. The special structural failure process and mode of multi ribbed composite walls are different from traditional walls. To fully utilize the excellent structural performance in building construction and improve the seismic performance of the building, based on the transformation principle of subset optimization algorithm for optimization problems, a constrained subset simulation optimization algorithm suitable for optimizing the maximum displacement angle of multi ribbed composite wall panels is designed. The Bayesian algorithm is used to construct a restoring force model for multi ribbed composite wall panels. The constrained subset simulation optimization algorithm and resilience model are used to optimize the seismic performance of 4-layer multi ribbed composite wall panels. The results show that the section height and the equivalent slant support width of the continuous column for the 4-story multi ribbed composite wall panel change from discrete distribution to aggregation with the increase of iteration. Finally, the sampling is stable in the 9th floor. At this time, the section height of the continuous column is 230 mm, and the equivalent slant support width is 525. After optimization, the failure probability of both extreme displacement angle states has decreased. When the peak ground acceleration is 1.0 g, the optimized second limit state failure probability is less than 100%. When the peak ground acceleration value is between 0.2 g and 0.6 g, both limit states show a rapid upward trend. The constrained subset simulation optimization algorithm and Bayesian quantitative resilience model proposed in the research can effectively optimize the seismic performance of multi ribbed composite walls.

This paper develops a new exterior prefabricated composite wall panel composed of light-gauge steel studs, profiled steel sheet and steel fiber-reinforced concrete. To investigate its performance, static loading tests are conducted on five wall panel specimens. The failure modes, load–displacement curves and cross-sectional strain distributions of the specimens under uniformly distributed loads are obtained and analyzed. The influences of stud spacing, wall panel section configuration and loading patterns on the flexural performance of the composite wall panels are systematically examined. Relevant finite element models are established and comparative analyses are conducted between the test results and the numerical simulation results. A theoretical analytical model is developed for the composite wall panels and an approximate method for calculating deflection is proposed based on the principle of minimum potential energy.

According to the special forms and mechanical behavior of frame-composite walls, displacement calculation method for frame-composite walls under horizontal loads is proposed in this paper. The model of frames and composite walls in parallel is adopted for considering working together of them. Cracking of filling blocks at middle and end elastic stages is taken into account. Based on material and structure mechanics theories, the displacement calculation method of frame-composite walls is derived from that of frame structures. The calculation results of the proposed method agree well with the test results of multi-grid composite wall with edge frame columns reinforced by steel. The displacement calculation method of frame-composite walls is compatible with that of frames and that of RC shear walls. The shear deformation of the frame-composite wall contributes most to the whole deformation. And the lateral displacement curves of middle to high-rise frame-composite wall structures are characterized by flexure-shear deformation. The proposed displacement calculation method for frame-composite wall structures can be used as a reference for structural design