The NES (nonlinear energy sink) is a new type of nonlinear tuned mass damper that is connected to the shock-absorbing main structure through strong nonlinear stiffness and viscous damping. The vibrational energy in the main structure is transferred to the NES oscillator by means of target energy transfer. A shaking table test of a 1:4 scaled RC (Reinforced Concrete) frame structure model with a new type of NES shock absorber was conducted to study the damping effect of the NES shock absorber, especially for the influence of joint strength and deformation. The NES used in this experiment has a relatively large nonlinear stiffness and a wide vibration absorption frequency band. The variation of reinforcement strains, node failure mode, and structural natural frequency of 1 story and two-layer joints of the model frame structure with NES were studied. The test results showed that NES could effectively reduce the strains of longitudinal reinforcement and stirrup in beams and columns and delay the plastic hinge development at the bottom and the top of the column. The frame model with NES installed has failures at the beam ends and shear failures at the nodes, realizing the seismic mechanism of solid columns and weak beams. Compared with ordinary seismic structures, the NES can effectively reduce the shear stress of concrete at the joints and alleviate the shear failure of joints. The final failure of the NES shock absorbing structure was the yielding of the steel bars at the bottom of the column and the crushing of the concrete at the foot of the column, and the connection between the column foot and the backplane became loose simultaneously. The decreasing rate of the vibration frequency declined due to the NES with varied broadband absorbing capability. It can be seen that the NES shock absorber not only has a good effect on reducing the seismic response of the structure, but more importantly, the damage of the structural nodes is greatly reduced, and therefore, the seismic capacity of the structure improved.

This paper proposes a new type of composite box beam combined with cold-formed thin-walled steel and glued laminated timber to develop green building structures while improving the load-carrying capacity of a single steel girder and glued timber girder. Two composite beams composed of laminated timber and Q235 cold-formed thin-walled steel were designed and fabricated. Then, the shear performance test with quadratic loading was carried out to analyze the load carrying capacity, damage modes, and deformation characteristics of the test beams, as well as their influencing factors. Subsequently, a finite element model of the composite beam was established, and the loading mode was the same as that of the test to further study the parameters affecting the shear performance of the composite beam. The results of the study indicate that steel and glued timber in composite beams connected by adhesive bonding can work and deform together under load and each give full play to its material properties, especially the composite beams, which exhibit higher shear strength than a steel or timber beam. The effects of parameters such as steel cross-sectional area, shear span ratio, steel skeleton form, and steel cross-sectional strength on the shear capacity of the composite beams were observed, among which the shear span ratio had the greatest effect on the shear capacity of the composite beams. The shear capacity decreased by 14.3% and 19.5% when the shear span ratio was increased from 1.5 to 2.0 and 2.5, respectively. The shear capacity of the combined composite beams increased by 10.6%, 6.3%, and 5.8% when the thickness was increased from 1.5 mm to 2.0 mm, 2.5 mm, and 3.0 mm, respectively. When the combination of the steel cross-section was a box beam, the overall shear-bearing capacity could be increased by 12% compared with the “I” type composite beam, although its shear stiffness was close to that of the “I” section composite beam.

Based on an engineering project, this paper initially establishes an observation point for foundation pit and then determines monitor warning value. During project construction, we carried out an experiment on the horizontal movement and settlement and inclination of adjacent buildings and promptly monitored the foundation pit., Scientific analysis of the data is presented. This work is designed to provide for effective measures to implement security alerts for foundation construction.. Detailed analysis examines the causes of deformation of foundation pit and offers a reasonable treatment measure. Results offer some scientific basis and technical measures to guarantee deep foundation project construction security and more knowledgeable engineering construction. With the rapid development of urbanization in China, the deep excavation works requirehave been put forward strict demand regulations concerningdue to the requirements of the spatial location, structural stability and using function. Deep excavation engineering is mostly carried out in areas of heavy traffic and dense construction. The complexity associated with deep excavation depth and difficult construction creates environments where serious accidents can occur. The deep excavation work is a wide-ranging and integrated engineering process. Previous research on accidents in national deep foundation pit engineering found the general accident ratio was about 20% of that of the deep excavations work (Tang, 1997),. Most accidents in urban areas were caused by foundation pit support. In deep excavation engineering, both the strength and deformation of the supporting structure and the surrounding environment affected by pit deformation should be considered (Sun, 2006). The pit support systems are always temporary facilities with fewer safety considerations and more hazards. Working status and conditions are more complicated and uncertain. Thus, during the construction process, dynamic monitoring and control is very important. The content of deep excavation-site monitoring generally includes the horizontal displacement of supporting structure, tilt displacement of neighboring buildings, sedimentation of adjacent roads and so on. A monitoring crew should provide timely feedback information (Liu, 2006) to detect any problems and provide early warnings for reducing disasters. A monitoring program that provides critical information and manages deep excavation construction scientifically and effectively is the key to successful deep excavation construction (Liu et al., 2007).

Five kinds of herbaceous plants commonly distributed in cold regions were selected as experiment plants for protecting slopes. According to the study of coverage, proportion of the root system, and shear strength of root-soil composite in the growth period of plants, the affectivity of slope protection of herbaceous plants in cold regions was verified. By experimentation of the root system, the Lucerne and June grass have a large extent of root system sand robust main roots. In the experiment of the shear strength of root-soil composite, the Lucerne had the largest shear strength and was followed by the White clover. The results of experiments verified that the herbaceous plants selected with good adaptability could protect slopes and enhanced slope stability, which produces better landscape effects under representative soil conditions in cold regions.

An objective function directing the characteristics of herbs slope was built by using the theory of AHP and Fuzzy math theory, and based on it, a Fuzzy Optimization model for comprehensive assessment of Herbs Slope project was built. Five plant species, Festuca rubra L., Medicago sativa L., Trrifolium repens L., Coronilla varia L. and Poa pratensis L. were tested. Using the model based on the index of growth rate, coverage, drought resistance, leanness resistance, shear strength of soil, which containing plant roots in anti-drawing strength of different herb, the conclusion is that the effectiveness of Festuca rubra L. slope is the best. Coronilla varia L. is better by applying a model selected to comprehensive assessment, which provides a scientific and effective decision-making method of designing and assessing the effectiveness of herbaceous plants on the slope of highways.

Purpose: The purpose of this paper is to describe the structure of nonlinear dampers and the dynamic equations, and nonlinear realization principles and optimize the parameters of nonlinear dampers. Using the finite element method to analyze the seismic performance of the frame structure with shock absorber. Design/methodology/approach: The nonlinear shock absorber was installed in a six-storey reinforced concrete frame structure to study its seismic performance. The main structure was designed according to the eight degree seismic fortification intensity, and the time history dynamic analysis was carried out by Abaqus finite element software. EL-Centro, Taft and Wenchuan seismic record were selected to analyze the seismic response of the structure under different magnitudes and different acceleration peaks. Findings: Through the principle study and parameter analysis of the nonlinear shock absorber, combined with the finite element simulation results, the shock absorption performance and shock absorption effect of the nonlinear energy sink (NES) nonlinear shock absorber are given as follows: first, the damping of the NES shock absorber is satisfied, and the linear spring stiffness and nonlinear stiffness of the shock absorber are based on the relationship k1=kn×kl2, so that the spring design length is fixed, and the linear stiffness of the shock absorber can be obtained. The nonlinear shock absorber has the characteristics of high rigidity and frequency bandwidth, so that the frequency is infinitely close to the frequency of the main structure, and when the mass of the shock absorber satisfies between 0.056 and 1, a good shock absorption effect can be obtained, and the reinforced concrete with the shock absorber is obtained. The frame structure can effectively reduce the seismic response, increase the natural vibration period of the structure and reduce the damage loss of the structure. Second, the spacer and each additional shock absorber have a small difference in shock absorption effect. After the shock absorber parameters are accurately calculated, the number of installations does not affect the shock absorption effect of the structure. Therefore, the shock absorber is properly constructed and accurately calculated. Parameters can reduce costs. Originality/value: New shock absorbers reduce earthquake-induced damage to buildings.