Biocatalysis for the synthesis of fine chemicals is highly attractive but usually requires organic (co‐)solvents (OSs). However, native enzymes often have low activity and resistance in OSs and at ...elevated temperatures. Herein, we report a smart salt bridge design strategy for simultaneously improving OS resistance and thermostability of the model enzyme, Bacillus subtilits Lipase A (BSLA). We combined comprehensive experimental studies of 3450 BSLA variants and molecular dynamics simulations of 36 systems. Iterative recombination of four beneficial substitutions yielded superior resistant variants with up to 7.6‐fold (D64K/D144K) improved resistance toward three OSs while exhibiting significant thermostability (thermal resistance up to 137‐fold, and half‐life up to 3.3‐fold). Molecular dynamics simulations revealed that locally refined flexibility and strengthened hydration jointly govern the highly increased resistance in OSs and at 50–100 °C. The salt bridge redesign provides protein engineers with a powerful and likely general approach to design OSs‐ and/or thermal‐resistant lipases and other α/β‐hydrolases.
By removing unfavorable surface salt bridges, the organic solvent and thermal resistance of enzymes can be significantly improved. This design strategy results in locally refined flexibility and strengthened hydration.
This paper addresses the lifecycle cost assessment of a steel girder bridge considering the material costs and maintenance activities along the bridge's lifecycle. A reference highway bridge case ...study is chosen. It was initially designed using carbon steel S355. Two more steel grades are included in the comparison: high strength carbon steel S460 and duplex stainless steel EN 1.4162. For each design option, fatigue appears to be the driving design criterion for the following critical welded details: transversal stiffeners, cope holes and full penetration butt welds in the flanges. In addition to ultimate limit state verifications, specific attention is therefore given to fatigue through the use of different verification methods: the well-known nominal stress method and the hot spot stress method. It is concluded that the net present value of the lifecycle cost of the stainless steel option is attractive compared to painted the carbon steel options.
•Comparative design of a highway girder bridge was performed.•Designs made of S460 and EN 1.4162 were compared to the initial design of S355.•Ultimate, serviceability and fatigue limit states are considered.•Life cycle cost assessments are carried out for each design.•The feasibility of each option is discussed.
Der sechsstreifige Ausbau der A3 zwischen dem AK Fürth/Erlangen und dem AK Biebelried führte zum Neubau eines Überführungsbauwerks ohne Mittelunterstützung mit 70 m lichter Weite. Als Ergebnis eines ...Realisierungswettbewerbs wurde ein integrales Bogenfachwerk als Auftaktbauwerk ausgewählt. Die innovative Verknüpfung von Bogen und Fachwerk führte zu einem sehr effizienten und robusten Tragwerk und einer äußerst flachen Überspannung der Autobahn. Bei der Planung wurden alle Aspekte der Nachhaltigkeit berücksichtigt – Wirtschaftlichkeit, Dauerhaftigkeit, Umweltverträglichkeit und Ästhetik. Innovative Details wie eine Bordsteinlinienentwässerung oder eine besondere Gestaltung der Untersicht mit gevouteten Fertigteilen führten zu einem Maximum an Funktionalität und Dauerhaftigkeit in Kombination mit guter Gestaltung. Für diesen Beitrag zur Formenvielfalt im heutigen Brückenbau erhielt das Bauwerk den Deutschen Ingenieurpreis Straße und Verkehr 2023 in der Kategorie Baukultur.Herrn Prof. Dr.-Ing. Thomas Ummenhofer zur Vollendung seines 60. Lebensjahres gewidmet
Abstract
In the trend of information technology, BIM Technology has been widely used in the design, construction and maintenance stages of bridge engineering activities with its own advantages. At ...present, BIM Technology has made further development to realize the bridge life cycle information. In view of the shortage of information carrier in the application of EBS in BIM life cycle, this paper proposes a 2-dimensional EBS coding system component decomposition coding system. The 2-D EBS coding system is composed of component information and subsidiary information. Through the practical application of Shapotou Yellow River Bridge in Ningxia, the possibility of 2-D EBS coding system in bridge life cycle information integration, exchange and storage is further verified. It provides a link role for bridge life cycle informatization, and has strong engineering practice significance.
Automation and robotics are integral parts of many industries but their potential for field implementation has not been significantly recognized by the construction industry. This is mainly ...attributed to conventional construction and design practices which undermine the benefits offered by these new technologies such as repetitions, precision, time savings, and increased safety. There is a need for advanced materials and 3D-printing systems which are capable of constructing structural elements with performance that emulates conventionally cast elements. This study presents a detailed framework and performance metrics for materials and 3D-printing systems for bridge applications. In addition, a study was carried out on ultra-high-performance concrete (UHPC) which showed sufficient extrudability and workability for 3D-printing applications. A 3D-printing system was developed for 3D-printing of continuous additive layers of UHPC with accelerated heat curing. Accelerated heat curing was used to enhance buildability, expedite the printing of the UHPC layers, and maximize the number of printed layers within the material open time. The effect of heat curing on material properties was also evaluated to obtain the optimal temperature to satisfy compressive strength requirements. This research effort aims to augment automated construction techniques and develop solutions to extend the applications of accelerated bridge construction.
High-pier railway bridges are mostly applied in mountainous areas. Due to the large spatial flexibility of the high piers under train dynamic loads, especially under braking conditions, the ...wheel-rail (WR) dynamic interaction may become more intense in the longitudinal direction, which could induce larger deformation and impact on the train-track-bridge (TTB) coupled system. To investigate the dynamic characteristics of such complex and large system during train braking condition, a 3D train-slab track-high pier bridge (TTHPB) coupled dynamics model is established and verified by considering the system longitudinal vibrations and the spatial flexibility of high piers. In this work, the influence of concerned bridge height from 60 to 160 m on the dynamic performances of the TTHPB system under train braking condition is studied. Results indicate that the operation speed has a significant effect on carbody acceleration and WR force. The longitudinal carbody acceleration due to its high-frequency vibration, as well as its noticeable amplitude induced by the long-time frequent braking, should be carefully considered in the evaluation of riding comfort index. The longitudinal dynamic behaviour of the high pier bridge is considerable and should be paid full attention to in bridge design compared with the other two directions.
•Effects of UHPC and stud diameters on shear behaviors of headed studs are studied.•Specimens with identical geometry showed different post-peak behaviors and large slip.•Existing formulae of shear ...capacity of headed studs are evaluated by data of collected 120 push-out specimens.•Formulae in existing codes overestimated the shear capacity of headed studs in UHPC.
Featuring high compressive and tensile strengths, ultra-high performance concrete (UHPC) is an efficient and durable alternative for conventional concrete in steel–concrete composite sections. However, few experimental studies to date have involved large diameter (≥ 25 mm) headed studs, UHPC with compressive strengths larger than 130 MPa, and relatively low strength but cost-effective UHPC. This study investigates the shear performance of steel headed studs embedded in UHPC through pushout tests with 24 specimens. Specimens included headed studs with diameters of 16 mm, 19 mm, 22 mm, and 25 mm, and either UHPC with compressive strength of 152.5 MPa or a cost-effective UHPC with a strength of 85.7 MPa (named as HPC hereafter). The results showed that smaller-diameter specimens (16 or 19 mm) failed with stud shank fracture, while the larger-diameter specimens (22 or 25 mm) failed at welding lines. Compared to HPC, UHPC did not notably increase the performance of headed shear strength. The load response consisted of a linear stage, a softening stage, and a post-peak stage lasting up to a slip of 10 mm or greater, with high variability in post-peak response among specimens with identical parameters. A global database of 120 push-out test specimens from this study and references was established, covering concrete strengths from 23.5 MPa to 152 MPa. The formulae given by AASHTO LRFD Bridge Design Specification, Eurocode-4, and Chinese code GB50017-2003 overestimated the shear capacity of headed studs by 52 %, 5 % and 53 %, respectively. The equation for the slip modulus slightly overestimated the slip modulus of headed studs. In conclusion, this study broadened the ranges of concrete strength and diameter of headed shear studs, and revealed that the existing equations of predicting shear capacity and slip modulus need improvement.
Drainage of road bridges Nikolov, Peter
IOP conference series. Materials Science and Engineering,
12/2023, Letnik:
1297, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
When designing bridges, the main focus is usually on the design of structural elements. However, some important issues related to the safe operation and maintenance of these facilities are ...sometimes ignored. One such issue is related to the drainage of bridge roadways. In some countries with a well-working system of inspection and maintenance of road networks and of bridges in particular, there are clear rules for the design of bridge drainage. Unlike the common practice in Bulgaria, the goal of bridge drainage design in these countries is to minimize the number of scuppers and to look for appropriate ways to minimize the amount of water in the bridge area. In this paper, the available requirements of Bulgarian design documents and regulations related to drainage systems are studied and a comparison with the bridge design manuals of some US transportation administrations is made
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