Mechanical Properties of Aluminium Bracket Strengthening

The aim of the research is laboratory investigation of aluminium brackets employed to fasten lightweight curtain walls to building facilities. Tensile loads perpendicular to end plates (vertical) were applied here. The author focused on the solutions intended to increase the load-carrying capacity of aluminium brackets applying the plain washer form A (DIN 125; ISO 7089), plain washer with an outer diameter about 3d (DIN 9021; ISO 7093) and additional cover plates (straps) in the location of bolt anchoring on the base plate. The aluminium brackets were tested on a steel base and concrete substrate. The flexibility of anchoring strongly affects the increase of the end plate middle point displacement and movable crosshead displacement.

Accuracy of Merging Point Clouds at the Maximum Range of a Scanner with Limited Possibilities of Target Placement

The research was aimed at analysing the factors that affect the accuracy of merging point clouds when scanning over longer distances. Research takes into account the limited possibilities of target placement occurring while scanning opposite benches of quarries or open-pit mines, embankments from opposite banks of rivers etc. In all these cases, there is an obstacle/void between the scanner and measured object that prevents the optimal location of targets and enlarging scanning distances. The accuracy factors for cloud merging are: the placement of targets relative to the scanner and measured object, the target type and instrument range. Tests demonstrated that for scanning of objects with lower accuracy requirements, over long distances, it is optimal to choose flat targets for registration. For objects with higher accuracy requirements, scanned from shorter distances, it is worth selecting spherical targets. Targets and scanned object should be on the same side of the void.

Experimental Investigations of Concrete Filled Battened Steel Columns of Different Slenderness

The study investigates the axial load behaviour of concrete filled battened steel columns not covered by the design standards. A series of full scale tests on two I-sections connected together with intermediate batten plates and filled with concrete were carried out. The main parameters varied in the tests are length of the members and strength of the concrete filling. One bare steel member was also tested and results were compared with those filled with concrete. The tests results were illustrated by load-strain curves. The main objectives of these tests were twofold: first, to describe behaviour of new steel-concrete columns and second, to analyze the influence of slenderness on load-carrying capacity.

The Concept of Method of Detecting and Analyzing Construction Defects in Residential Buildings

The authors developed the definition of construction defect and fault and construction defect management based on Polish and foreign publications. In order to assist identification of faults and their analysis in the process of home collection, the authors applied the Case Based Reasoning (CBR) method. In the paper, the authors used Case Based Reasoning (CBR) to support acceptance of apartments. The CBR method allows to determine the magnitude of global similarity for the problem under consideration between the new and old case from the Case Base, using weighted sums of local similarities using criteria weights as coefficients. As a result of CBR-based solutions, an Employer’s representative receives information about the type of construction defects that can be expected, their location and significance, occurrence frequency, and estimated repair cost.

Effect of Selected Friction Stir Welding Parameters on Mechanical Properties of Joints

The article discusses the basic issues related to the technology of friction stir welding (FSW). A short description of technology is provided. The following section provides the analysis of effect of technological parameters (tool rotation and welding speed) on the mechanical properties of the prepared joint (strength, ductility, microhardness). In both cases the analysis refers to aluminum alloys (6056 and AA2195-T0). The comparative analysis showed the phenomenon of the increase in weld strength along with the increase in the rotational speed of the tool during welding. Similarly, with the increase in welding speed, an increase in weld strength was observed. Some exceptions have been observed from the above relations, as described in the article. In addition, examples of material hardness distribution in the joint are presented, indicating their lack of symmetry, caused by the rotational movement of the tool. The analyses were performed basing on the literature data.

Preliminary Evaluation of Seismic Performance of Engineering Structures with PERFORM 3D

This study analyzed the role of PERFORM 3D in the preliminary evaluation of seismic performance of engineering structures. Firstly, PERFORM 3D was briefly introduced, and its material constitutive model and basic model were analyzed. Then, taking a high-rise building project in Yulin, Shaanxi, China, as an example, PERFORM 3D was used to evaluate its seismic performance. After establishing the engineering model, five seismic waves were selected for simulation. The results showed that the maximum values of X-axis inter-story displacement angle and Y-axis displacement angle were 1/500 and 1/360 respectively, which were far less than the standard limit; the overall energy dissipation was good, the damping was small, the overall deformation was good, and the seismic performance was also good. In conclusion, PERFORM 3D has a good performance in the preliminary evaluation of seismic performance of engineering, and it is worth further promotion and application.

Parametric Analysis of the Sensitivity of a Prestressed Concrete Beam Using the DOE Simulation Technique

The paper presents the method of simplified parametric analysis of the sensitivity of a pre-tensioned concrete beam. The presented approach is based on the DOE (design of experiments) data collection which is simulation technique allowing for identification of variables deciding about the effectiveness and costs of designed structures. Additionally, application of the hyper-surface of the construction response allows designers to the development of multi-dimensional trade-off graphs to facilitate, the assessment of the scope of changes in random state variables permitted due to the adequate criteria and selection of their values close to optimum. Design basics, procedures and results of the presented considerations of sensitivity assessment and reliability of the structure has been shown on the example of a pre-stressed concrete beam designed in accordance with the requirements and procedures of Eurocode 2

Model of Construction Subcontractors Selection with Time Windows for their Availability

Most construction projects involve subcontracting some work packages. A subcontractor is employed on the basis of their bid as well as according to their availability. A viable schedule must account for resource availability constraints. These resources (e.g. crews, subcontractors) engage in many projects, so they become at the disposal for a new project only in certain periods. One of the key tasks of a planner is thus synchronizing the work of resources between concurrent projects. The paper presents a mathematical model of the problem of selecting subcontractors or general contractor’s crews for a time-constrained project that accounts for the availability of contractors, as well as for the cost of subcontracting works. The proposed mixed integer-binary linear programming model enables the user to perform the time/cost trade-off analysis.

Design Using Special Steel Sheet Profiles – Procedures Developed within the Framework of Grispe and Grispe Plus Projects

New computational procedures developed within the framework of international research projects „Grispe” and „Grispe Plus” are briefly presented and characterised here. Considered algorithms pertain to the verification of bearing capacity and serviceability of selected bearing structure components erected with especially shaped thin-walled sheet metal panels. Structural components of this type are so far rather absent from the codes, and as a result the unequivocal design requirements have not been developed for them. Key problems related to the detailed analysis of the following element classes: steel decks with embossments, indentations and/or outwards stiffeners; liner trays; corrugated sheeting; curved profiles; cladding and roof profile assemblies; perforated and holed profiles; external interlocking planks and their assemblies are indicated in the text. The procedures formulated as a part of the projects indicated above have been delivered to CEN as an official proposal of amendments and/or additions submitted for introduction to the new generation of Eurocodes currently under preparation, and especially as an extension to the code EN 1993-1-3.

The Structure of the Optimal Control in the Problems of Strength Optimization of Steel Girders

The paper concerns a strength optimization of continuous beams with variable cross-section. The continuous beams are subjected to a dead weight and a useful load, the six (seven) combinations of loads were analyzed. Optimal design problems in structural mechanics can by mathematically formulated as optimal control tasks. To solve the above formulated optimization problems, the minimum principle was applied. The paper is an introductory and survey paper of the treatment of realistically modelled optimal control problems from application in the structural mechanics. Especially those problems are considered, which include different types of constraints. The optimization problem is reduced to the solution of multipoint boundary value problems (MPBVP) composed of differential equations. Dimension of MPBVP is usually a large number, what produces numerical difficulties. Optimal control theory does not give much information about the control structure. The correctness of the assumed control structure can be checked after obtaining the solution of the boundary problem.