Due to the low density and stiffness of wood, traditional timber floor systems are prone to producing large vibration responses. By combining timber beams with concrete floors, timber–concrete composite (TCC) floor systems show stronger bearing capacity, higher bending stiffness, and better thermal and sound insulation behaviors when compared with traditional timber floor systems. In this study, the vibration performance of TCC beams with crossed inclined coach screw connectors was investigated using dynamic tests. The influence of the screw diameters and slab dimensions on the dynamic performance of the composite beams was evaluated. The test results demonstrated that TCC beams show good dynamic performance when used as a floor component and meet the preliminary requirements of floor vibration comfort for fundamental frequency. The fundamental frequency and damping ratio of TCC beams decreases with the increase in slab dimensions. The bending stiffness and natural frequency of TCC beams decrease smoothly when reducing the screw diameter from 16 to 12 mm. Additionally, two theoretical models were used to predict the natural frequencies of the TCC beams, and the predicted values show good consistency with the measured ones.

Timber–concrete composite structure is a type of efficient combination form composed of concrete floors and timber beams or floors through shear connectors, and shows good application potential in the floor system of timber buildings. The long-term performance of the timber–concrete composite structures is complex and is affected by the creep of timber and concrete, as well as the long-term slip of the shear connectors. This article presents a comprehensive overview of the research status on the long-term behavior of timber–concrete composite members and different shear connectors. For the shear connectors, the effects of loading levels, environments, and component materials on their creep coefficients are summarized. As to the timber–concrete composite members, both the experimental and numerical investigations are gathered into discussions: the connection types, component materials, loading conditions, and durations in the long-term tests are also discussed; various models for describing long-term behavior of timber, concrete, and connection systems are provided, and then a comprehensive description of the progress of numerical investigations over the last decades is made. In addition, the suggestions for future research are proposed to reach a clearer understanding of the bending mechanisms and mechanical characteristics of timber–concrete composite structures.

This paper presents the push-out experimental results of hybrid notch-screw (HNS) connections for timber-concrete composite structures. A total of 7 groups of specimens were designed and tested. The experimental parameters included the loading constraint conditions (i.e., the test specimens were loaded either in local compression or in uniform compression), shapes of notches in the wood, screw number in notch, notch width, and the inclusion of a self-tapping screw reinforcement for timber or not. The experimental results were discussed in terms of failure modes, ultimate strength, slip moduli, and ductility. The yield strengths and ductility factors were determined based on the load-slip curves according to existing standards. The experimental results showed that both the shear timber width and the self-tapping screw reinforcement played important roles in terms of the ultimate strengths, ductility, and deformability. Rectangular notched connections with screw reinforcements displayed timber shear failure coupled with brittle failure. With the trapezoidal notch, the ductility of the connections improved, coupled with a decrease in the slip modulus. The self-tapping screw reinforcement for shear timber could greatly improve the ductility performance of the HNS connections. The slip modulus models for the connection with vertical deep notches were provided, which were in agreement with the experimental results.

In this study, the human-induced vibration performance of an innovative Deltabeam–CLT composite floor system was investigated. The Deltabeam–CLT composite floors were modelled using the finite element software package ABAQUS 6.14, the dynamic performance of the composite floors was evaluated, and the simulation results were benchmarked against prior simulation data in the other literature. In order to investigate the effect of the stiffness of Deltabeam composite steel beams on the vibration performance of Deltabeam–CLT composite floors, the acceleration of the Deltabeam–CLT composite floors under the excitation of a single person walking was measured. As per the acceleration, serviceability factors, namely, response factors (RFs) and vibration dose values (VDVs), were analyzed. The results showed that an increase in the height of Deltabeam composite steel beams can decrease the RF and VDV by 53.7% and 57.7%, respectively. This study also developed an optimization scheme with steel trusses pre-embedded inside Deltabeam composite steel beams. The effects of different truss spacing and rod diameters on the vibration performance of the Deltabeam–CLT composite floors were investigated; the results showed that the RF and VDV of Deltabeam–CLT composite floors can decrease to below 4 and 0.4 m/s^−1.75, respectively, with a truss spacing smaller than 200 mm. These findings can significantly enhance the future design of the Deltabeam–CLT composite floor system, improving its serviceability and ensuring better performance in practical applications.

Screwed connections are widely adopted in timber–concrete composite (TCC) structures. Owing to the diverse connection configurations and complex shear mechanisms, existing empirical models or theoretical formulas cannot accurately and efficiently predict the shear modulus of a screwed connection. Therefore, this study develops machine learning (ML) algorithms to accurately predict the slip modulus. A data set including 222 sets of testing results was established by collecting the values of the slip modulus and associated ten features. Four ML methods, including decision tree (DT), random forest (RF), adaptive boosting machine (AdaBoost), and gradient boosting regression tree (GBRT), are adopted to develop the ML algorithm. The Shapley Additive Explanation (SHAP) framework was employed to interpret the effects of related features on the slip modulus. GBRT demonstrated the best accuracy compared with the other three ML methods in terms of four popular quantitative metrics. Moreover, all ML methods showed an evident accuracy advantage compared to existing analytical methods. Through a SHAP analysis, it was found that concrete strength, screw inclination, timber density, and timber type have a large impact on the slip modulus of a screwed connection compared to other input features.