Improving construction processes of concrete building structures using load limiters on shores

Abstract

_____________________________________________________________________________________ AbstractThis paper describes a computer tool for calculating and validating loads on floor slabs and shores in the construction of multistorey buildings with in situ casting. Its chief novelty lies in its optimization unit, designed to produce appropriate and optimum construction processes, which was created by applying exact and heuristic methods: Random Walk (RW), Descent Local Search (DLS) and Simulated Annealing (SA). The system has shown that it can improve three of the most important aspects involved in construction: time, cost and safety. In some cases the optimal solutions were achieved while reducing up to 53% of the cost of the shoring system, in shorter construction time, and meeting all the usual requirements for the construction of this type of building.

Maximum loads on shores during the construction of buildings

“…The building was fitted with test instrumentation (Alvarado, 2009;Alvarado et al, 2009) and analysed by finite-element method (FEM) and simplified calculation methods in terms of mean loads (Alvarado, 2009;Alvarado et al, 2010;Buitrago et al, 2015;Calderón et al, 2011). The maximum loads on the shores in each construction phase were determined from these recordings and results, which were also used to validate the simplified calculation procedure for maximum loads proposed in the present paper.…”

“…3.1 Description of the test building The building used for the study was the one studied by Alvarado (2009), Alvarado et al (2009) and Buitrago et al (2015), consisting of three 0·25 m thick reinforced concrete floor slabs, 2·75 m inter-floor height and an inter-column distance of 6·00 m. Figure 3 shows a view of the building under construction and a scheme of its geometric definition.…”

“…In this case, the loads given by the simplified method also show a good fit with the FEM results for the different levels: 20·72 kN as opposed to 21·37 kN on level 1, 9·03 kN as opposed to 9·25 kN on level 2, and 8·42 kN as opposed to 8·33 kN on level 3. A summary of both options for setting the shore design load is given in Table 2, in which it can also be seen that the simplified maximum load calculation method (NSP) shows a good Alvarado et al (2009Alvarado et al ( , 2010 and Buitrago et al (2015). Finally, it is fundamental to highlight the importance of considering the calculation of maximum loads on shores instead of only considering load transmission in terms of mean loads.…”

“…The evolution of the elasticity modulus with time was estimated by the maturity technique described in detail in Alvarado (2009) and applied by Waller et al (2004), Adam et al (2007), Gasch (2012) and Buitrago et al (2015). Additionally, the stiffness matrix method was considered to calculate the necessary M 1 and M 2 moments.…”

Stage of construction: An essential consideration in designing reinforced concrete building structures

“…Following previous studies and including the effect of creep in the concrete, the considered hypotheses in the stage of construction were as follows: Linear elastic behavior of concrete in slabs, columns, and beams with variations of stiffness with time. Formwork boards, straining pieces, and shores with linear elastic behavior and finite stiffness. Infinitely stiff foundations. Effects of creep as in ETABS using the expressions proposed in the Model Code Shrinkage and temperature variations in the different structural elements were not considered. …”