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Research area and topicality of the work. Large equipment such as pressure vessels, mining equipment, heat exchangers, steam generators and other structures are provided with bolted closures for the purpose of in-service inspection and maintenance of internal components. The serious stress concentrations existing at the thread roots often cause danger of low cycle fatigue failure of the connectors. The load distribution along the threads has a direct influence on the stress at the thread roots. Load distribution in thread is so very unequal that some turns may be over the plastic yield limit but other turns are only in an elastic state. It is very useful to find the load distribution laws within threaded connection for elasto-plastic state of turns because it gives primary data for predicting low cycle durability of whole connection. Up to now low cycle fatigue calculating methods directly do not use data of the load distribution in thread. Instead of it the influence of some structural features to the low cycle durability somewhere approximately are evaluated by constant factors. That is insufficient because many structural parameters of threaded connections which influence to load distribution are designed in wide range of dimensions. Trustworthy way for more exact calculation of the stress at the thread roots is direct use of load distribution data. It is unavoidable when in order to increase thread connections fatigue life advanced techniques for improvement of load... [to full text]

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Denna rapport undersöker hastighetsberoende friktionsbeteende i zinkpleterade 8.8 M12x1.75 skruvförband med en klämlängd på 82 mm och ett åtdragningsmoment på 120 Nm. Totalt 84 åtdragningar genomförs med nya skruvar, brickor och muttrar för varje åtdragning med utrustning tillhandahållen av Atlas Copco. All data importeras och analyseras i Matlab. Analysen visar att inom en standard avvikelse från medelvärdet kan klämkraften variera med så mycket som 90% beroende på var inom det 10-200 rpms hastighetsspannet skruven drogs åt. Vidare framgår även att restmomentet är mycket beroende av den hastighet som skruven drogs åt vid, med ett restmoment ~5 Nm över slutmomentet för 10 rpm och ~20 Nm över slutmomentet vid 200 rpm. En ursprunglig hypotes tas fram som antar att en utförlig modell av lastfördelningen i skruvensgänga och under skruvens skalle kan användas för att förutse skruvförbandets friktionsbeteende. Denna hypotes övergavs då mätresultat och analys visar att effekten av en förbättrad lastfördelningsmodell inte skulle märkas då spridningen i friktionen är för stor. / This report examines the speed dependency of frictional behavior in zinc plated 8.8 M12x1.75 bolt joints with an 82 mm clamping length at a tightening torque of 120 Nm. A total of 84 test tightenings have been performed with new bolts, nuts and washers for each tightening. The tests are performed using equipment supplied by Atlas Copco and all data is imported and analyzed in Matlab. It is found that within one standard deviation of the mean value the clamping force can vary as much as 90% depending on where in the 10-200 rpm speed range the bolt is tightened. Furthermore it is concluded that the residual torque is also highly speed dependent, registering at ~5 Nm above the final torque at 10 rpm and ~20 Nm above at 200 rpm. An initial hypothesis was developed regarding the pressure distribution in the thread and under the bolt head in the hopes that better understanding and modeling of this aspect could help predict frictional behavior in the bolt joint. This hypothesis was abandoned after it is concluded that the impact of an improved pressure model would be much too small to be noticeable due to the already large scatter in frictional coefficients.

The diploma thesis deals with the design of a steel technological structure in the locality of Štětí. The struture is used for the paper production technology. The geometry of the structure was customized to technological requests. The statistic system was considered in two versions – joint connections and frame – joint connections. The frame – joint connections system was chosen for detail processing. The steel structure was calculated by Scia Engineer 19 software. The connections were calculated by Idea statica software. The thesis is processed according to valid standars of ČSN EN.

The theme of the master’s thesis is to design steel structures sports hall. The proposal is developed in three variants according to ČSN EN. The work addresses the static effect of the steel structure and design of parts and materials design. Plan dimensions are 60x38m, max. internal height is 9,3m. The structure is designed for ultimate limit states and serviceability. The supporting structure is designed as roof arches surround an elliptical girder. In both gable walls are designed steel columns. The work also details and solution design. Sports hall was solved in Scia Engineer 2011 and includes a drawing documentation.

he master’s thesis consists of a case study of an observation tower design made of glue laminated timber and steel. There are two different tower shapes of anchored or free standing tower and these towers are compared. One of the design is chosen and elaborated into final detailing. A short review of main issues bound with the observation towers is given. The review deals mainly with loading (mainly priniples wind loads are analised) and evaluating of towers (ultimate limit states, service limit states and acceleration comfort). The height of final construction is up to 60m. The design is formed by a space lattice structure made of glue laminated timber and steel members of different class. The members are fastened mainly by means of dowel joints with slotted-in-plates . There is a light steel stairway inserted into the main structure.