Operational Problems in Structural Nodes of Reinforced Concrete Constructions

Abstract

Reinforced concrete structures are frequently designed and executed in such facilities as: halls, warehouses, factories, multi-family buildings, single-family buildings, tanks, silos and many others. For this type of structures, it is particularly relevant to provide an appropriate thickness of concrete lagging, which aims at protecting reinforcement against corrosion, and to design it with appropriate spacing allowing the in-between space to be filled with a concrete mix. A frequent problem met while making reinforced concrete structures is such a density of reinforcing bars, particularly within structural nodes, that there is no possibility of filling the space between them with a concrete mix or it is not possible to vibrate the concrete mix in order to prevent segregation of mixture components. Structural nodes are points where special attention should be paid to careful compaction of concrete mixes and application of measures that prevent concrete from adhering to molds. The case study illustrates two structural nodes connecting a column with a bolt, located in a wall with a column-transom structure. During the modernisation works carried out in the production hall there were exposed two structural nodes completely unfilled with a concrete mix and with visible reinforcing bars that showed little buckling and the onset of corrosion. The columns, due to their location in the general static scheme of the wall, were subjected to compression or locally compressed and affected by bending. Particularly unfavourable was the fact that the columns did not feature the concrete lagging in the compression zone of the element. Removal of concrete lagging in the compression zone always results in decrease in the bearing capacity of a structure. It can be concluded that due to faulty workmanship the columns had a lower load bearing capacity than anticipated in the building permit design. The paper provides software-derived guidelines for repairing reinforced concrete columns so as to obtain the value of load bearing capacity equal or higher than expected in the design and on the assumption that repair works would be carried out on columns subjected to loading.

Numerical Analysis of the Impact of Thermal Spray Insulation Solutions on Floor Loading

“…Damage to floor plates caused by the adoption of incorrect reinforcement or the faulty execution of reinforced concrete structures is a serious problem for the user of the facility. Numerous authors have considered this subject [4,39,40]. Although the literature includes papers discussing issues related to the bending of plates on an elastic foundation, they refer to the stratified soil below the floor [9,13,14].…”

Numerical Simulation of Dynamic Response and Evaluation of Flexural Damage of RC Columns under Horizontal Impact Load

“…The concrete material is simulated using the concrete damaged plasticity (CDP) model in the ABAQUS material library, in which the constitutive relation under the uniaxial state is set according to the Code for Design of Concrete Structure (GB50010-2010) [17], as seen in Table 1. Meanwhile, since the paper simulates the impact load, instead of the long-term static load, the influence of the concrete aging [18] was not considered. To consider the enhancement effect of the strain rate on concrete material, the calculation equations of the dynamic compressive and tensile strengths suggested by the Comité Euro-International du Béton (CEB) [19] are utilized: ε is the strain rate; σ c,d and σ t,d are the dynamic compressive strength and dynamic tensile strength, respectively; and σ c,s and σ t,s are the compressive and tensile strengths under quasi-static conditions corresponding to the reference strain rates .…”

Optimal Design of Bubble Deck Concrete Slabs: Sensitivity Analysis and Numerical Homogenization

“…The idea of ceiling technology has remained unchanged in its general concept for years. Every floor should meet certain requirements whether revitalizing a building or building a new one, and the design requirements determine the choice of technology and construction [ 13 , 14 ]. These requirements can be divided into technical and economic requirements.…”