Joint Layout Design: Finding the Strongest Connections within Segmental Masonry Arched Forms

Segmental arched forms composed of discrete units are among the most common construction systems, ranging from historic masonry vaults to contemporary precast concrete shells. Simple fabrication, transport, and assembly have particularly made these structural systems convenient choices to construct infrastructures such as bridges in challenging environmental conditions. The most important drawback of segmental vaults is basically the poor mechanical behaviour at the joints connecting their constituent segments. The influence of the joint shape and location on structural performances has been widely explored in the literature, including studies on different stereotomy, bond patterns, and interlocking joint shapes. To date, however, a few methods have been developed to design optimal joint layouts, but they are limited to extremely limited geometric parameters and material properties. To remedy this, this paper presents a novel method to design the strongest joint layout in 2D arched structures while allowing joints to take on a range of diverse shapes. To do so, a masonry arched form is represented as a layout of potential joints, and the optimization problems developed based on the two plastic methods of classic limit analysis and discontinuity layout optimization find the joint layout that corresponds to the maximum load-bearing capacity.

Prenatal murine skeletogenesis partially recovers from absent skeletal muscle as development progresses

Skeletal muscle contractions are critical for normal growth and morphogenesis of the skeleton, but it is unclear how the detrimental effects of absent muscle on the bones and joints change over time. Joint size, shape and cavitation, and rudiment length and mineralisation were assessed in multiple rudiments at two developmental stages (Theiler Stage (TS)24 and TS27) in the splotch-delayed 'muscleless limb' mouse model and littermate controls. As development progressed, the effects of absent muscle on all parameters except for cavitation become less severe. All major joints in muscleless limbs were qualitatively and quantitatively abnormal in shape at TS24, while, by TS27, most muscleless joint shapes were normal, or nearly normal. In contrast, any joints which were fused at TS24 did not cavitate by TS27. Therefore, recovery in joint shape over development occurred despite absent cavitation. Mineralisation showed the most pronounced changes between TS24 and TS27 in the muscleless limbs. At TS24, all muscleless rudiments studied had less mineralisation than the controls, while at TS27, muscleless limb rudiments had either the same or significantly more mineralisation than controls of the same age. We conclude that the effects of absent muscle on prenatal murine skeletogenesis are most pronounced in early skeletal development and reduce in severity prior to birth. Understanding how mammalian bones and joints continue to develop in an environment without muscle contractions, but with mechanical stimulation due to the movement of the mother, provides important insights into conditions affecting human babies such as developmental dysplasia of the hip and arthrogryposis.

Strength & Conduct of Reinforced Concrete Corner Joint under Negative Moment Effect

The aim of our study is to reveal the effect of steel reinforcement details,tensile steel reinforcement ratio, compressed reinforcing steel ratio,reinforcing steel size, corner joint shape on the strength of reinforcedconcrete Fc' and delve into it for the most accurate details and concreteconnections about the behavior and resistance of the corner joint ofreinforced concrete, Depending on the available studies and sources inaddition to our study, we concluded that each of these effects had a clearrole in the behavior and resistance of the corner joint of reinforced concreteunder the influence of the negative moment and yield stress. A studyof the types of faults that can be reinforced angle joints obtains detailsand conditions of crushing that are almost identical for all types of steelreinforcement details and the basic requirements for the acceptable behaviorof reinforced concrete joints in the installations and the efficiency of thejoint and this may help us to prepare for disasters, whether natural or other,as happens with tremors The floor and failure that may occur due to wrongdesigns or old buildings and the possibility of using those connections totreat those joints and sections in reinforced or unarmed concrete facilitiesto preserve the safety of humans and buildings from sudden disasters andreduce and reduce risks, as well as qualitative control over the productionof concrete connections and sections free from defects to the extreme.

An Experimental Investigation on the Repairing Performance and Fatigue Life of Asphalt Pavement Potholes With an Inclined Interface Joint

A pothole is a typical structural damage of asphalt pavements that significantly influence the life of asphalt pavements and driving safety. The durability of the existing pit repair methods is generally low. The existing studies in the context of pothole repair mainly focus on the selection and the amount of tack coat materials, nonetheless, very limited studies emphasize the effect of the joint interface shape. This study aims to investigate the influence of the interface joint shape on the service life of pothole repair by experimental testing. The strength and fatigue behavior of the joints were studied and the effectiveness of pothole repairs was evaluated under various conditions, including four temperature levels (5, 10, 15 and 25°C), four strain levels (750 με, 1,000 με, 1,250 με, and 1,500 με) and three loading frequencies (2, 5, and 10 Hz). The optimal interface joint shape was obtained by orthogonal tests. The results indicated that the bond strength and fatigue life of the high viscoelastic emulsified asphalt with an area density of 0.6 kg/m2 in the form of a 30° inclination joint was 473 and 80 times higher than those of traditional pothole repair (i.e., vertical joint form and no tack coat), respectively. Finally, a prediction model was proposed for the interface joint fatigue life considering external parameters through multiple regression analyses. This prediction model can provide a reference for the further study of asphalt pavement pothole repair.

Biogeography a key influence on distal forelimb variation in horses through the Cenozoic

Locomotion in terrestrial tetrapods is reliant on interactions between distal limb bones (e.g. metapodials and phalanges). The metapodial–phalangeal joint in horse (Equidae) limbs is highly specialized, facilitating vital functions (shock absorption; elastic recoil). While joint shape has changed throughout horse evolution, potential drivers of these modifications have not been quantitatively assessed. Here, I examine the morphology of the forelimb metacarpophalangeal (MCP) joint of horses and their extinct kin (palaeotheres) using geometric morphometrics and disparity analyses, within a phylogenetic context. I also develop a novel alignment protocol that explores the magnitude of shape change through time, correlated against body mass and diet. MCP shape was poorly correlated with mass or diet proxies, although significant temporal correlations were detected at 0–1 Myr intervals. A clear division was recovered between New and Old World hipparionin MCP morphologies. Significant changes in MCP disparity and high rates of shape divergence were observed during the Great American Biotic Interchange, with the MCP joint becoming broad and robust in two separate monodactyl lineages, possibly exhibiting novel locomotor behaviour. This large-scale study of MCP joint shape demonstrates the apparent capacity for horses to rapidly change their distal limb morphology to overcome discrete locomotor challenges in new habitats.