The article presents the ideas of flexible design in the construction sector. Flexibility in the construction sector was discussed and defined between typical and flexible approaches to design. The idea applied during the economic effectiveness analysis of construction projects was introduced. The issue of flexibility was discussed based on the example of construction of a sports facility - The National Stadium in Warsaw. An effectiveness analysis was applied for variant solutions.
The study deals with stability and dynamic problems in bar structures using a probabilistic approach. Structural design parameters are defined as deterministic values and also as random variables, which are not correlated. The criterion of structural failure is expressed by the condition of non-exceeding the admissible load multiplier and condition of non-exceeding the admissible vertical displacement. The Hasofer-Lind index was used as a reliability measure. The primary research tool is the FORM method. In order to verify the correctness of the calculations Monte Carlo and Importance Sampling methods were used. The sensitivity of the reliability index to the random variables was defined. The limit state function is not an explicit function of random variables. This dependence was determined using a numerical procedure, e.g. the finite element methods. The paper aims to present the communication between the STAND reliability analysis program and the KRATA and MES3D external FE programs.
In the paper, the Hasofer-Lind index is applied for determining the probability of stability loss oftruss structure under random load. In 1974 Hasofer-Lind proposed a modified reliability index thatdid not exhibit the invariance problem. The “correction” is the evaluation the limit state functionat a point known as the “design point”, instead of the mean values. The design point is generallynot known a priori, an iteration technique must be used to find out the reliability index. The papershows how the reliability index changes under the influence of different variables mean value,standard deviation, and probability density function.
The objective of the milk-run design problem considered in this paper is to minimize transportation and inventory costs by manipulating fleet size and the capacity of vehicles and storage areas. Just as in the case of an inventory routing problem, the goal is to find a periodic distribution policy with a plan on whom to serve, and how much to deliver by what fleet of tugger trains travelling regularly on which routes. This problem boils down to determining the trade-off between fleet size and storage capacity, i.e. the size of replenishment batches that can minimize fleet size and storage capacity. A solution obtained in the declarative model of the milk-run system under discussion allows to determine the routes for each tugger train and the associated delivery times. In this context, the main contribution of the present study is the identification of the relationship between takt time and the size of replenishment batches, which allows to determine the delivery time windows for milkrun delivery and, ultimately, the positioning of trade-off points. The results show that this relationship is non-linear.