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Currently, new housing in city centers is more and more often developed on small plots of land, or existing buildings on such plots are rebuilt to such an extent that only their façade walls remain. In both cases, as a rule, a deep excavation is also made, either at the existing object or within its area. Serious damage often occurs because of the carried out work. It is not possible to accurately determine the response of a building to the deformation associated with the excavation due to the variability of many factors that influence it. As a result, the response of the building must be estimated on the basis of constant monitoring and approximate calculations. Depending on the size of the predicted ground displacements and the technical condition of buildings, it is often necessary to protect or strengthen their structural elements. In the paper, the authors analyzed various risk factors for the implementation of infill buildings and the revitalization of historic buildings using only their façade walls. In addition, examples of contemporary solutions for securing the walls of existing buildings, and the method of monitoring vertical deformations using the Hydrostatic Levelling Cell (HLC) system, are presented. [ABSTRACT FROM AUTHOR]

Currently, new housing in city centers is more and more often developed on small plots of land, or existing buildings on such plots are rebuilt to such an extent that only their façade walls remain. In both cases, as a rule, a deep excavation is also made, either at the existing object or within its area. Serious damage often occurs because of the carried out work. It is not possible to accurately determine the response of a building to the deformation associated with the excavation due to the variability of many factors that influence it. As a result, the response of the building must be estimated on the basis of constant monitoring and approximate calculations. Depending on the size of the predicted ground displacements and the technical condition of buildings, it is often necessary to protect or strengthen their structural elements. In the paper, the authors analyzed various risk factors for the implementation of infill buildings and the revitalization of historic buildings using only their façade walls. In addition, examples of contemporary solutions for securing the walls of existing buildings, and the method of monitoring vertical deformations using the Hydrostatic Levelling Cell (HLC) system, are presented.

In this paper the temporary support structures in construction are classified into frame support structures, truss support structures，hybrid support structures and special support structures based on their assembly patterns and mechanical behaviors. Frame support structures are classified into structures with and without X-bracing. The units for each type of structure are determined. The simplified calculation models which consider the rotational stiffness of joints and the continuity of horizontal tubes are put forward according to analysis of overall three-dimensional structures. Corresponding stability equations are derived. The calculation formulas for effective length factors of frame support structures are obtained. Some correction coefficients which consider the influence of the height of bottom transom, the length of U-head, the height of structures, etc. are proposed. The method for overall and local stability calculation of truss support structures is given. A unified theory for stability analysis of temporary support structures assembled with tubes and couplers, buckle bowls, disk locks or other fittings is established. The research contributes to the work on 'Technical code for temporary support structures in construction' (JGJ 300--2013). [ABSTRACT FROM AUTHOR]

• The dynamic response laws of the central diaphragm structure after the explosion were studied according to the field monitoring. • The damage characteristics of the central diaphragm near the blasting source were investigated and the four stages of the failure evolution were summarized. • The vibration response and the failure modes of the central diaphragm structure under the condition of different charge quantities and blasting distances were simulated. • The relation function containing the blasting tensile stress index was obtained through dimensional analysis. The blasting impact poses a serious threat to the safety of temporary support structures in tunnel blasting construction, such as a temporary middle wall. Thus, this study investigated and explored these problems. First, the dynamic response results of the temporary middle wall after the explosion were studied according to the field monitoring data. Subsequently, the damage characteristics of the temporary middle wall near the blasting source were investigated on field, and the development stages of the failure evolution were summarized. Furthermore, combined with the explicit finite element software LS-DYNA, the fluid–solid coupling algorithm was used to simulate the vibration response and the failure modes of the temporary middle wall under the condition of different charge weight and blasting distances. According to the field investigation, the closest blasting holes away from the temporary middle wall had a much more significant impact on its damage than other holes. The failure reason of the sprayed concrete of the supporting structure is caused by the excess high peak tension or compression stress. The failure process of supporting structure can be divided into four development stages with the reduced distance away from the blasting source: the appearance of the cracks, the cracks interconnect to form large X-shaped cracks, structural bending-shear coupling failure, and instability failure. The displacement values of the steel arch in the temporary middle wall continuously exceed 7 cm, 20 cm, 28 cm, and 34 cm, respectively, corresponding to the above four failure stages. The relation function containing the blasting tensile stress (BTS) parameter is obtained through dimensional analysis, which can be directly used to design and the damage evaluated of temporary support structures subjected to blasting at close range. [ABSTRACT FROM AUTHOR]