The tensile capacity of bored piles in frictional soils

2008 ◽  
Vol 45 (12) ◽  
pp. 1715-1722 ◽  
Author(s):  
Sven Krabbenhoft ◽  
Allan Andersen ◽  
Lars Damkilde

Three series of 10 piles each were installed in two different locations. The lengths of the piles varied from 2 to 6 m and the diameters were 14 and 25 cm. The piles were constructed above the groundwater table using continuous flight augers and the concrete was placed by gravity free fall. The piles were tested to failure in axial uplift and the load–displacement relations were recorded. The results from the tests have been compared with theoretical values based on current design practice and the method proposed by Fleming et al. seems to produce the best match with the test results.

Author(s):  
R. C. Fenwick ◽  
L. M. Megget

In regions, described as plastic hinge zones, in beams and columns, tensile yielding of the reinforcement through flexural action can occur in severe earthquakes. Where the beams and columns are lightly loaded, axially, member elongation can occur. Test results show that axial extensions of the order of several percent of the member depth may be expected. This deformation, which is ignored in current design practice, can have a major influence on the distribution of forces in a structure and its ability to survive without collapse. This paper describes the way in which elongation develops in plastic hinge zones together with the form of load deflection characteristics associated with the development of different types of plastic hinge zone.


Author(s):  
L. Xu ◽  
J. Liu ◽  
S. Fox ◽  
Y. Liu

Lapped joints of cold-formed steel Z-shaped purlins are extensively used in metal building roof construction to create multi-span purlin systems. Conventionally, round holes are used in the lapped purlin connections. With the advantage of providing extra installation tolerance, vertical slotted holes are widely used in the lapped joints of cold-formed steel Z-shaped purlin systems to simplify and expedite the erection of multi-span purlin roof systems. However, the current design practice is based on the research for the lapped connections with round holes. Almost no research has been conducted to investigate effects of vertical holes on the flexural behaviour of cold-formed steel Z-shaped purlins. To investigate the effects of vertical slotted holes on the structural behaviour of lapped cold-formed steel Z-shaped purlins, tests were performed on the lapped purlins with different lap lengths, purlin depths, thicknesses and spans. The results show that the flexural strength and stiffness of the lapped purlins with vertical slotted holes are primarily influenced by three parameters, i.e., the ratio of lap length to purlin depth, the ratio of lap length to purlin thickness, and the ratio of purlin depth to purlin thickness. Based on the test results, design recommendations are proposed for designing lapped cold-formed steel Z-shaped purlins with vertical slotted holes.


1991 ◽  
Vol 18 (6) ◽  
pp. 926-932 ◽  
Author(s):  
Seshu Madhava Rao Adluri ◽  
Murty K. S. Madugula

The concept of schifflerization of 90° equal-leg angle is presented and its application in triangular-base latticed steel towers is explained. The similarities and differences between schifflerized angles and regular 90° angles are discussed. The current design practice for schifflerized angles is reviewed and its limitation is highlighted. A design method which includes the effect of the torsional-flexural buckling mode of failure is proposed. For ready use of designers, the factored axial compressive resistances of schifflerized angles are tabulated for both the present and proposed design methods. Key words: buckling, compressive resistance, design criteria, schifflerized angles, stability, standards, steel, struts, towers, guyed towers.


2011 ◽  
Vol 243-249 ◽  
pp. 258-262
Author(s):  
Jun Chen ◽  
Jia Lv ◽  
Qi Lin Zhang ◽  
Zhi Xiong Tao ◽  
Jun Chen

Laminated glass has been increasing widely used in high rise buildings as a kind of safety glass in recent years. So we should analyze its material property. In this paper, we use flexural experiments and ANSYS program to analyze the main factors that affect the flexural capacity of the laminated glass. The test results show that the flexural capacity is closely related to film. And the ANSYS program had got good agreement with the experimental results. Comparison of experimental results with calculated ones indicates that the current design code will lead to conservative results and the equivalent thickness of laminated glasses provided in the code should be further discussed.


1981 ◽  
Author(s):  
Deborah W. Berman

This study develops a simplified comparative procedure for use in preliminary yacht design to predict Equilibrium sideforce, resistance, leeway angle and speed made good to windward for a canoe hull sailing yacht within specific form parameters on any of five standard series keels. These forces, angles and speeds are predicted for any yacht hull resembling one of nine models - ranging from light to medium-heavy length to displacement ratio - (190 to 351) - of the Delft Systematic Series for which there is numerical data. The forces are calculated at speed to length ratio of 1. 3 and heel angle of 30° to enable the designer to make use of existing comparative sail plan and rigging data. The five keels of varying aspect and area ratio, spanning current design practice, are part of a matrix developed at the Davidson Laboratory. In this paper, a canoe yacht hull form similar to Model 7 of the Delft Series is tank tested on 3 Standard Series keels and compared to results obtained from testing a 5.5 m hull, which is similar to Model 8, on the same keels. A prediction procedure is developed and checked against test results. A few Equations, selected values from included tabulations, a calculator, pencil and paper will yield quantitative information for the yacht designer in the selection of a keel for the hull of a sailing yacht.


PCI Journal ◽  
2022 ◽  
Vol 67 (1) ◽  
Author(s):  
Jörn Remitz ◽  
Martin Empelmann

Pretensioned concrete beams are widely used as bridge girders for simply supported bridges. Understanding the fatigue behavior of such beams is very important for design and construction to prevent fatigue failure. The fatigue behavior of pretensioned concrete beams is mainly influenced by the fatigue of the prestressing strands. The evaluation of previous test results from the literature indicated a reduced fatigue life in the long-life region compared with current design methods and specifications. Therefore, nine additional high-cycle fatigue tests were conducted on pretensioned concrete beams with strand stress ranges of about 100 MPa (14.5 ksi). The test results confirmed that current design methods and specifications overestimate the fatigue life of embedded strands in pretensioned concrete beams.


Author(s):  
Ирина Рыбникова ◽  
Irina Rybnikova ◽  
Александр Рыбников ◽  
Aleksandr Rybnikov

One of the methods of improving the bearing capacity of bored piles is giving them a taper. The feature of these (wedge-type) piles is that under load they work "as a thrust" and transfer part of the load due to the normal component to the inclined side surface. Three sizes of tapered bored piles were tested, with the length of 4.5 m, head diameter 0.4; 0.5; 0.6 m and with cone angle 1o and 2,5o. The test results were compared with the test results of cylindrical piles, 4.5 m long, with head diameter 0.4 m and 0.6 m. It has been discovered that with the increasing cone angle, the bearing capacity of piles against the pressing load, especially the specific load capacity for 1 m3 of material, as compared to cylindrical piles, increases significantly. It has been determined that the larger is the diameter of the head of the pile, the higher is the bearing capacity against the horizontal load, and the bearing capacity against the pullout load is equal to the breakout force of a pile from the soil.


2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Lara Furniss

Since 2000, design practice in the UK has changed dramatically. Boundaries between design disciplines have dissolved, and many contemporary design studios now defy classification. These studios are reconfiguring the design landscape, yet a uni-disciplinary structure still dominates undergraduate education. This is creating a disconnection between practice and education and posing critical questions for the current design education system. This article outlines the findings of a PhD research study exploring this disconnection, and although situated within the UK, the findings have international relevance. An initial scoping exercise draws on interviews with leading commentators from the UK design sector, examining the evolution of design practice over the past 10 years, and possible future directions for undergraduate education. Findings highlight that UK policy for creative education has placed undergraduate design courses in potential crisis. Arguably, the current university system for design education is outdated. It is now necessary to redefine the skills and processes twenty-first-century designers need. The body of the research is situated within five internationally renowned creative studios which defy classification. In-depth ethnographic studies cross-analyse the creative processes of these studios and their views on education. Findings identify key components of each studio’s processes, while also exploring studio members’ educational experiences, and reflections on future implications for pedagogy. This article argues that this growing disconnect between practice and education calls for existing pedagogic models to be challenged, proposes alternative approaches and highlights the need for policymakers, practitioners and educators to work together to best prepare young designers to meet today’s challenges.


Author(s):  
Mahadi Mahadi ◽  

This article contains a study report on the manufacturing of bicycle helmet models that use polymeric foam composite materials strengthened by oil palm empty fruit bunch (OPEFB). The test results of mechanical polymeric foam obtain tensile stress (σt) 1.17 MPa, compressive stress (σc) 0.51 MPa, bending stress (σb) 3.94 MPa, modulus of elasticity (E) 37.97 MPa, density ( ρ) 193 (kg / m3). The testing results of thermal conductivity (k) with ASTM C177-04 standard obtain 0.096 W/mK. Aerodynamic simulation is carried out on 5 bicycle helmet models with different variations of air ventilation formations and obtained the M4A model that best met the ergonomic criteria. The simulation results of the M4A helmet model are max 65.668 Pa of air pressure (Pu), 26,8 0C of inner wall temperature (Ti), 11.0724 m/s of air velocity (vi) and 0.89 of drag coefficient (CD). Bicycle helmet manufacturing is carried out by hand lay up method for shell layer and casting mold for liner by using GFRP polymer composite molds. Both layers are made by sandwich method with the composition of the shell layer is 100 grams resin, 15 grams glass fiber and 5 grams catalyst. The composition of the liner layer is 275 grams (50%) of unsaturated Polyester 157 BQTN-EX resin, 27.5 grams (5%) of OPEFB fiber, 247 grams (45%) of Blowing Agent Polyurethane and 27.5 grams (5%) of Methyl Ketone Perokside catalyst (MEKPO). The toughness of the helmet is tested by using a free fall drop test with the standard of Consumer Product Safety Commission (CPSC) with the height of impact 1.5 meters. The free fall drop test results are max 2.02 MPa of the impact stress of the M4A bicycle helmet model (σi) and max 283.77 joules of energy impact (Ei) which is close to the Consumer Product Safety Commission’s (CPSC) standard value of 110 joules.


2014 ◽  
Author(s):  
Elzbieta M. Bitner-Gregersen ◽  
Torfinn Hørte ◽  
Lars Ingolf Eide ◽  
Erik Vanem

Global warming and extreme weather events reported in the last years have attracted a lot of attention not only in academia and media but also in the shipping industry. Three important questions have been in focus: will occurrence of extreme weather events increase in the future, which geographical locations will be most affected, and to what degree will climate change affect future ship traffic and design of ship structures. Observed and projected changes in wave conditions are expected to have the largest effect on ship design and operations in comparison to other environmental phenomena. The present study briefly summarizes recent investigations addressing changes of significant wave height in the North Atlantic, including the last findings of IPCC (Intergovernmental Panel on Climate Change), and discusses how these changes can be included in environmental description used for ship design. It is also interesting to notice that climate changes resulting in some ocean regions in increase of storm activity (intensity, duration and fetch) and changes of storm tracks may result in secondary effects such as increased frequency of occurrence of abnormal waves, also called rogue or freak waves. This study shows how the scientific findings on climate change and rogue waves can be incorporated in the risk-based approach used in current design practice of tankers, and ships structures in general. Further, it demonstrates the effect of climate change and rogue waves on tanker design, particularly on the safety level of current design practice. Finally, the present paper discusses how structural design of ships can be upgraded to account for climate change and rogue waves but economic consequences do not need to be significant.


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