Search Results (62)

Ensuring vibration and impact isolation is crucial in industrial flooring design, especially where vibroacoustic comfort is a priority. Excessive vibrations can negatively affect sensitive equipment, structural durability, and personnel comfort. With the rise of automation and high-precision processes, effective vibration control in floor systems is increasingly important. Traditional solutions like elastomer pads, rubber mats, or floating floors often have high installation costs, complex construction, and long-term degradation. Therefore, there is growing interest in integrated, durable alternatives that can be incorporated directly into concrete structures. One such approach uses rubber granulates from recycled tires as a modifying additive in cementitious composites. This can improve damping, enhance impact energy absorption, and reduce the need for external insulating layers. However, adding rubber particles to concrete may affect its compressive strength, a key design parameter. This article presents experimental research on concrete and mortar mixtures modified with rubber granulates for vibration-isolating industrial floor systems. The proposed solution combines a conventional concrete subbase with a rubber-enhanced mortar layer, forming a composite system to mitigate vibration transmission. Laboratory tests and real-scale verification under industrial conditions showed that the slab with hybrid EPDM/SBR rubber granulate mortar achieved the highest vibration-damping efficiency, reducing vertical acceleration by 58.6% compared to the reference slab. The EPDM-only mortar also showed a significant reduction of 45.5%. Full article

To address the challenges of slow construction and high self-weight in steel–concrete composite floors for rural light steel frame structures in China, a new prefabricated floor system was developed. This system features prefabricated slabs made from recycled concrete, connected via reinforced shear pocket joints. In seismic environments, assembly floor joints often become vulnerable points, making their shear resistance particularly crucial. This study investigated the shear performance of this new type of floor joint, examining the effects of various parameters such as joint configuration, stud diameter, recycled concrete strength, and grout strength. A refined finite element model was established for an in-depth parameter analysis. The research revealed stud–shear failure as the mode of floor joint failure under different design parameters. The detailed design of the new joint structure ensures safety in the floor joint area. Increasing stud diameter, recycled concrete strength, and grout strength all contributed to enhancing the joint’s shear capacity and stiffness, with stud diameter having the most significant impact. Higher recycled concrete strength improved shear capacity, although its influence decreased beyond a certain threshold. Optimal reserved hole diameter proved beneficial for enhancing joint shear performance, with a diameter of 40 mm showing superior performance. Full article

In order to reduce the self-weight of steel sheet–concrete composite slabs and fully apply the superior performance of the composite slabs, this paper proposes a kind of open-profiled steel sheet–hollow concrete composite floor slab. Flexural behavior tests are conducted to five pieces of composite floor slabs with different parameters, and numerical simulation methods were applied to perform finite element analysis on the composite slabs with different hollow rates, reinforcement ratios, and steel sheet thicknesses. At the same time, the calculation methods were discussed for the flexural bearing capacities under different anchorage conditions. The results indicate that, when the profiled steel sheet is in a low anchorage degree, end debonding is one of the important failure modes for the composite floor slabs, and the flexural bearing capacity of the composite floor slabs is significantly reduced. The reinforcement arrangement in the tensile zone has a significant impact on the bearing capacity, deflection, and ductility coefficient of the composite floor slabs. When the reinforcement ratio increases from 0% to 0.6%, the ultimate bearing capacity is increased by 182.5%, and the ductility coefficient is increased by 246.0%. The ultimate deflection of specimens with a reinforcement ratio of 0.6% is 22.4 times of that of the specimens without reinforcement arrangement. When the hollow rate is less than 20%, the influence of the concrete hollow radius on the flexural bearing capacity, ductility coefficient, and maximum crack width is relatively small. As the thickness of the steel sheet increases, the increasing range in ultimate bearing capacity gradually decreases, the deflection gradually decreases, and the ductility coefficient gradually increases; increasing the thickness of composite floor slabs can help reduce deformation. The theoretical calculation values obtained by applying the flexural bearing capacity calculation method proposed in the paper match with the test results, and the method has a certain reference value for the engineering practice. Full article

Under the impetus of achieving global sustainable development goals, the civil construction industry is accelerating its transition towards high-quality, green, and low-carbon practices. Prefabricated, modular building technology has become a key tool due to its advantages in energy conservation, emission reduction, and shortened construction periods. However, existing research on the seismic performance of prefabricated, modular, reinforced concrete column–beam (RCS) composite structures often focuses on the construction form of beam–column joints, paying less attention to the impact of floor slabs on the seismic performance of joints during earthquakes. This may make joints a weak link in structural systems’ seismic performance. To address this issue, this paper designs a prefabricated, modular RCS composite joint considering the effect of floor slabs and uses the finite element software ABAQUS 2023 to perform a quasi-static analysis of the joint. The reliability of the method is verified through comparisons with the experimental data. This study examines various aspects, including the joint design and the material’s constitutive relationship settings, focusing on the influence of parameters, such as the axial compression ratio and floor slab concrete strength, on the joint seismic performance. It concludes that the seismic performance of the prefabricated, modular RCS composite joints considering the effect of floor slabs is significantly improved. Considering the composite effect of the slabs, the yield loads in the positive and negative directions for node FJD-0 increased by 78.9% and 70.0%, respectively, compared to that of the slab-free node RCSJ3. The ultimate bearing capacities improved by 13.2% and 9.98%, respectively, and the energy dissipation capacity increased by 23%. Additionally, the variation in the axial load ratio has multiple effects on the seismic performance of the joints. Increasing the slab thickness significantly enhances the seismic performance of the joints under positive loading. The bolt pre-tensioning force has a crucial impact on improving the bearing capacity and overall stiffness of the joints. The reinforcement ratio of the slabs has a notable effect on the seismic performance of the joints under negative loading, while the concrete strength of the slabs has a relatively minor impact on the seismic performance of the joints. Therefore, the reasonable design of these parameters can optimize the seismic performance of joints, providing a theoretical basis and recommendations for engineering application and optimization. Full article

Bamboo is a fast-growing biomass material with excellent performance, making it a preferred choice for the development of green and low-carbon building materials. However, challenges such as combustibility and difficulties in processing and utilization persist. In this study, bamboo chips are wrapped in fiberglass cloth and cemented with magnesium oxychloride cement (MOC) to develop green, environmentally friendly, flame-retardant, and carbon-storing bamboo-based composite panels. Firstly, the optimal ratio of the inorganic adhesive MOC was systematically investigated, and flue gas desulfurization gypsum (FG) was added to enhance its water resistance. The flexural strengths of the composite board in the direction of the bamboo fiber and that perpendicular to it were found to be 15.71 MPa and 34.64 MPa, respectively. Secondly, numerical simulations were conducted alongside plate experiments, analyzing the floor and wall made from the boards. The results indicate that since the fiber-reinforced bamboo board as a lightweight wall can meet the requirements for a two-story building, it does not satisfy safety standards as a floor slab due to the higher loads. Despite this limitation, the fiber-reinforced bamboo board shows promising application prospects as a green and low-carbon alternative. Full article

This study investigates the influence of phosphogypsum (PG) content on the mechanical properties of concrete composite slabs reinforced with steel trusses. Static load tests were conducted on five one-way composite slabs with varying PG contents (0%, 2%, and 4%), and finite element analysis (FEA) was employed to simulate and analyze the structural behavior. The effects of PG content on crack distribution, ultimate failure mode, cracking load, and stiffness prior to ultimate load were systematically evaluated. The results demonstrated that the FEA simulations closely matched the experimental data, accurately capturing the failure mechanisms of the PG-based composite slabs. The optimal PG content was determined to be 2%, as the composite slab with 2% PG exhibited comparable strength to the conventional concrete slab (0% PG) while maintaining superior structural integrity during failure. These findings highlight the potential of PG as a sustainable additive in concrete composite slabs, offering a viable solution for reducing environmental waste and enhancing structural performance. This study provides valuable insights into the development of eco-friendly building materials and contributes to the advancement of sustainable construction practices. Full article

The building and construction sector accounts for nearly 40% of global greenhouse gas emissions, with steel-framed buildings being a significant contributor due to high CO₂ emissions during production. To mitigate this issue, integrating Cross-Laminated Timber (CLT) into structural systems has emerged as a sustainable alternative. CLT, known for its carbon sequestration properties, offers an environmentally friendly replacement for reinforced-concrete slabs, particularly when paired with steel structures to enhance material reuse and reduce lifecycle impacts. This study focuses on hybrid systems combining H-shaped steel beams and CLT floor panels connected using high-strength friction bolts. A four-point bending test, simulating a secondary beam, was conducted, demonstrating that the composite effect significantly enhances flexural stiffness and strength. Additionally, a simplified method for evaluating the flexural stiffness and yielding strength of these composite beams, based on material and joint properties, was shown to successfully evaluate the test results. Full article

Straw–concrete combined floor slabs consist of straw boards, shear-resistant connectors, and concrete slabs. These slabs offer various advantages over traditional reinforced concrete slabs due to the straw boards’ properties of excellent insulation and sound absorption. Research using ABAQUS software created 15 composite floor models to study the impact of connection methods, bond strength, connector spacing, and thickness of straw and concrete on the flexural performance. Results indicated that the composite floor slab with adhesive bonding had a 7.34% and 17.34% higher load-carrying capacity than the bolt-connected and self-tapping screw-connected composite floor slabs, respectively. Increasing bond strength from 40 MPa to 60 MPa improved the load-carrying capacity of self-tapping nail-connected slabs by 80.84%. Connector spacing negatively correlated with slab capacity, while increasing the thickness of straw boards or concrete slabs enhanced the ultimate load-carrying capacity, with the latter having a more significant effect. Midspan deflection and flexural capacity were calculated using the converted cross-section method and static calculation formulas, with theoretical and simulated values showing good agreement, offering guidance for engineering applications. Full article

In order to solve the problems of high production cost and complex control of the inverted arch of an unsupported prestressed concrete composite slab, a flange truss high-ductility concrete composite slab floor is proposed to change the structure and pouring material to meet the requirements of no support during construction. The crack distribution and bending performance of the flange truss high-ductile concrete composite slab floor (CRHDCS) under different structures are clarified through the test and numerical analysis of four different rib plate structure floors. According to the analysis results, the calculation formulas of the cracking moment and short-term stiffness before cracking are modified, and the equivalent short-term stiffness formula of a single web member of the “V” truss to this kind of bottom plate is established. The results show that, unlike the short-term stiffness-change law of typical concrete composite slabs after cracking, the short-term stiffness of the designed bottom plate in this paper includes a short-term increase stage. The numerical simulation results are the same as the experimental ones; the maximum error is 10%. The maximum errors between the modified cracking moment and the short-term stiffness calculation formula are 6% and 8%, respectively. The influence rates of removing flange plate, truss-inverted binding, and adding rib plate on the cracking bending moment of foundation structure are −81.5%, 11.0%, and 22.2% respectively, and the influence rates on short-term stiffness are −87.6%, −1.5%, and 37.5% respectively. Full article

In order to explore the vibration mechanism of vibration damping composite floor slabs and further enrich the theory of floor slab vibration calculation, the free vibration characteristics of vibration damped composite floor slabs and the dynamic response of vibration damped composite floor slabs under multi-source excitation is analyzed using first type Chebyshev polynomials to construct the displacement function and derive an analytical solution. The three-dimensional laminated theory is employed, considering the interlayer interaction. Based on the proposed method, the influences of loading types, positions, magnitudes, and frequencies on the vertical vibration of floor slabs are calculated. The study illustrates that, under the action of multi-source excitation, the displacement and acceleration responses calculated by the method proposed in this paper are always greater than those calculated by the single-plate theoretical solution. The dynamic responses of the vibration damping composite floor slab decrease with the increase of the thickness and elastic modulus of the vibration damping layer. Under different thicknesses of the vibration damping layer, the peak accelerations of the vibration damping composite floor slabs increase linearly with the growth of the load amplitude. In addition, the load movement path has a significant effect on the vibration response of the floor slab. When the moving load moves along the short side of the floor, the displacement response of the floor is generally greater than that along the long side of the floor. Full article

Dynamic analysis of structures is a key challenge in structural engineering, especially in choosing effective and accurate numerical methods. Steel–concrete composite structures, commonly used in bridges and floors, require calculations of dynamic parameters to ensure safety and comfort. Few studies compare the effectiveness of the finite element method (FEM) and the rigid finite element method (RFEM) in the dynamic analysis of such structures. This study fills this gap by comparing the methods using experimental results. FEM and RFEM models were developed using Abaqus, Python, and Matlab. The main parameters were identified, i.e., the Young’s modulus of the concrete slab (E_C) and the stiffness of the connection (K_x, K_RX, K_v, K_h). Both methods closely matched the experimental results. The RFEM matched natural frequencies with 2–3% deviations, while the FEM showed 3–4% deviations for the torsional, axial, and first three flexural frequencies. The RFEM reduced the computation time by about 65%, making it suitable for large-scale applications. The FEM provided a finer resolution of local effects due to its higher element density. The results can be applied to the design of bridges, floors, and other structures under dynamic loads. It will also provide the authors with a basis for developing structural health monitoring (SHM). Full article

A top-chord-free Vierendeel-truss composite slab (TVCS) comprises a concrete slab, several vertical webs, and a steel bottom chord. In this study, static tests and finite element analyses were conducted based on an actual project to investigate the deformation, crack characteristics, ultimate bearing capacity, and failure mode of the composite slab. The findings indicated that the loading process of this type of floor can be divided into elastic, elastoplastic, and failure stages. The section stress distribution in the elastic stage was further analyzed. The crack development pattern exhibited a fine density in the pure bending sections of the concrete slabs, while demonstrating good overall flexural bearing capacity and ductility for the composite slab. Experimental results were compared with the ANSYS finite element model simulation to validate the accuracy of the simulation. Parametric analysis was conducted to assess the impact of concrete strength, steel strength, vertical web width, and distance ratios on the mechanical characteristics of the composite slab. By introducing an adjustment coefficient for the vertical web distance ratio, a revised calculation formula for flexural bearing capacity was proposed, which aligned well with the finite element analysis. Full article

The BlueDeck profiled steel sheeting system offers an innovative composite flooring solution, integrating high-strength steel sheets with reinforced concrete to form a unified structure. This study aimed to evaluate the development of full composite action, the ultimate bearing capacity, and the flexural stiffness of the system. A comprehensive experimental programme involving 18 four-point bending tests and 6 shear tests was conducted to quantify the mechanical interaction between the steel deck and concrete slab. This study specifically examined bending capacity and vertical deflection, comparing the results with predictions from AS/NZS 2327. It was found that the system consistently achieved full composite action, with composite specimens demonstrating higher flexural stiffness and load-bearing capacity as the concrete depth increased. For example, specimens with 200 mm slab depths exhibited a 60% improvement in ultimate capacity compared to those with 150 mm slabs, while those with 175 mm depths saw a 27% increase. Additionally, the BlueDeck system showed an 81% improvement in de-bonding resistance in thicker slabs. The experimental results exceeded the bending moment and deflection limits prescribed by AS/NZS 2327, confirming that the system is structurally sound for use in buildings. This study provides quantitative evidence supporting the system’s compliance with Australian standards, highlighting its potential for improving construction efficiency through reduced material use, while maintaining structural integrity under imposed loads. Full article

This study reveals the essential load-bearing characteristics of the steel–concrete composite floor system under fire conditions applying the structural stressing state theory. Firstly, the strain data in the entire process of the fire test are modeled as state variables which can present the slab’s stressing state evolution characteristics. Then, the state variables are used to build the stressing state mode and the parameter characterizing the mode. Further, the Mann–Kendall criterion is adopted to detect the leap points in the evolution curves of the characteristic parameters during the entire fire exposure process. Also, the evolution curves of the stressing state modes are investigated to verify the leap profiles around the leap/characteristic points. Finally, the detected leap points are defined as the failure starting points and elastoplastic branching points, which is unseen in past research focusing on the failure endpoint defined at the ultimate load-bearing state of the composite floor system. The failure starting point and the elastoplastic branching point are the embodiment of natural law from quantitative change to quality change in a system rather than an empirical and statistical judgment. Hence, both characteristic points avoidably exist in the strain data of the composite floor system undergoing the fire process, which can be revealed through the proper modeling methods and update the existing theories and methods on structural analysis and design in fire. Full article

In order to study how to improve the spatial action of precast monolithic composite floor slabs, and examine replacing the cast-in-place surface layer for reducing the weight of structure, we used pseudo-dynamic tests on one-quarter scale models of two-span and three-story frame structures. The lateral load tests compared the stresses and displacements with a cast-in-place floor frame–shear wall structure (SJ1) and a precast monolithic floor frame–shear wall structure with X horizontal braces at the bottom of the floor (SJ2). The results show the X horizontal braces can improve the spatial action. Structural integrity (SJ2) as well as the effective transmission of the horizontal force can be ensured by additional X bracing at the bottom of the rigidity of the floor without a cast-in-place concrete topping. The results show that X horizontal braces more effectively transfer horizontal stress, which provides a beneficial reference for similar research. Full article