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A strut-and-tie model (STM) for unsymmetrically-loaded deep beams is proposed in this paper through simplifying the unsymmetrical problem into symmetrical and anti-symmetrical problems. This analytical solution starts with derivations of principal compressive stress fields based on the theory of elasticity. Furthermore, a minimum-strain-energy criterion is adopted to define the optimal STM geometry from the stress field, including the dimensions of struts and nodal zones, and strut angles. The proposed STM is validated against 140 test results, including 14 unsymmetrically-loaded deep beams and 126 symmetric deep and short beams, and finite element models (FEMs) for the 14 unsymmetrical deep beams. The FEM is also used to simulate the load-displacement relationships of unsymmetrical deep beams that could not be modelled by STM. In addition, a worked example is presented to demonstrate in detail the procedure of analysing an unsymmetrically-loaded deep beam using the proposed solution. In summary, the STM predictions are in good agreement with experimental results and FEM predictions. Therefore, the proposed STM is capable of giving accurate and consistent predictions for both symmetrical and unsymmetrical deep and short beams. Ministry of National Development (MND) National Research Foundation (NRF) The authors wish to acknowledge the first authors scholarship from the Singapore Ministry of National Development and National Research Foundation under L2 NIC Award No. L2NICCFP1-2013-4.

Circular RNAs (circRNAs) play a significant regulatory role during skeletal muscle development. To identify circRNAs during postnatal skeletal muscle development in chickens, we constructed 12 cDNA libraries from breast muscle tissues of Chinese Gushi chickens at 6, 14, 22, and 30 weeks and performed RNA sequencing. In total, 2112 circRNAs were identified, and among them 79.92% were derived from exons. CircRNAs are distributed on all chromosomes of chickens, especially chromosomes 1–9 and Z. Bioinformatics analysis showed that each circRNA had an average of 38 miRNA binding sites, 61.32% of which have internal ribosomal entry site (IRES) elements. Furthermore, in total 543 differentially expressed circRNAs (DE-circRNAs) were identified. Functional enrichment analysis revealed that DE-circRNAs source genes are engaged in biological processes and muscle development-related pathways; for example, cell differentiation, sarcomere, and myofibril formation, mTOR signaling pathway, and TGF-β signaling pathway, etc. We also established a competitive endogenous RNA (ceRNA) regulatory network associated with skeletal muscle development. The results in this report indicate that circRNAs can mediate the development of chicken skeletal muscle by means of a complex ceRNA network among circRNAs, miRNAs, genes, and pathways. The findings of this study might help increase the number of known circRNAs in skeletal muscle tissue and offer a worthwhile resource to further investigate the function of circRNAs in chicken skeletal muscle development.

This paper focuses on the condition where a reinforced concrete (RC) deep beam is subjected to two concentrated loads (P1 and P2), which are positioned at respective distances a and c from bottom supports. In general, equal shear spans (a = c) and equal point loads (P1 = P2) are commonly assumed in most experimental programmes. Nevertheless, such cases are rare in practice. In contrast, due to the fact that deep beam floor normally subjects to irregular layout of column grid, deep beams are usually subjected to unequal load magnitude (load inequality or P1 ≠ P2) and unsymmetrical load positions (load asymmetry or a ≠ c). Although previous research has demonstrated the significant influences of load asymmetry and inequality on the structural performance of deep beams at room temperature, no research programme has been performed to study their influences on the fire performance of deep beams. As a result, this study is proposed to investigate the shear behaviour of unsymmetrically-loaded deep beams at fire condition, analytically and experimentally. The current research first derives a strut-and-tie-model (STM) to predict the shear capacity of RC deep beams under unequal/unsymmetrical loading conditions and at elevated temperatures. The STM takes into account the effects of unsymmetrical loading configurations, contribution of steel reinforcement on strut capacity, and thermal-induced gradient. Additionally, a test programme on six RC deep beams under fire condition is conducted for verification of the proposed model. Observations from this experimental programme show that load asymmetry and inequality have different effects on the fire performance of deep beams. To be more specific, an increase in load inequality leads to an alteration in failure mode of the deep beams, whist load asymmetry does not affect the failure mode as much. On the other hand, increasing load inequality can result in a significantly increased mid-span deflection at failure and a slightly increased failure time. Besides, effect of load inequality on deflection and failure duration depends on the loading positions. Furthermore, the proposed STM yields good agreement between test data and model predictions for unequally- and/or unsymmetrically-loaded deep beams, at both room and high temperatures. Ministry of National Development (MND) National Research Foundation (NRF) This research work is supported by the Singapore Ministry of National Development and National Research Foundation under L2 NIC Award No. L2NICCFP1-2013-4.

Several recent studies investigated the role of the miR-29 family in muscle development. However, only a few studies focused on chicken skeletal muscle. In the present study, cell cycle, 5-ethynyl-2’-deoxyuridine (EdU), cell counting kit-8 (CCK-8), and other assays indicated that miR-29b-1-5p can inhibit the proliferation of chicken primary myoblasts (CPMs); the western blot assay and immunofluorescence detection of MYHC demonstrated that miR-29b-1-5p can promote the differentiation of myoblasts. The functional enrichment analysis revealed that the target genes of miR-29b-1-5p may be involved in muscle tissue development, muscle organ development, and striated muscle tissue development, which are biological processes related to muscle development. The correlation analysis showed that these 6 genes, that is, ankyrin repeat domain 9 (ANKRD9), lactate dehydrogenase A (LDHA), transcription factor 12 (TCF12), FAT atypical cadherin 1 (FAT1), lin-9 homolog (LIN9), and integrin beta 3 binding protein (ITGB3BP), can be used as effective candidate target genes of miR-29b-1-5p. Moreover, miR-29b-1-5p inhibits the expression of ANKRD9 by directly binding the 3′UTR of ANKRD9. Overall, these data indicate that miR-29b-1-5p inhibits the proliferation of primary chicken myoblasts, stimulates their differentiation, and is involved in the process of muscle development and that its effective target gene is ANKRD9. This study identified the molecular mechanism of miR-29b-1-5p in chicken muscle development.

Circular RNAs (circRNAs) play important roles in adipogenesis. However, studies on circRNA expression profiles associated with the development of abdominal adipose tissue are lacking in chickens. In this study, 12 cDNA libraries were constructed from the abdominal adipose tissue of Chinese domestic Gushi chickens at 6, 14, 22, and 30 weeks. A total of 1,766 circRNAs were identified by Illumina HiSeq 2500 sequencing. These circRNAs were primarily distributed on chr1 through chr10 and sex chromosomes, and 84.95% of the circRNAs were from gene exons. Bioinformatic analysis showed that each circRNA has 35 miRNA binding sites on average, and 62.71% have internal ribosome entry site (IRES) elements. Meanwhile, these circRNAs were primarily concentrated in TPM < 0.1 and TPM > 60, and their numbers accounted for 18.90% and 80.51%, respectively, exhibiting specific expression patterns in chicken abdominal adipose tissue. In addition, 275 differentially expressed (DE) circRNAs were identified by comparison analysis. Functional enrichment analysis showed that the parental genes of DE circRNAs were primarily involved in biological processes and pathways related to lipid metabolism, such as regulation of fat cell differentiation, fatty acid homeostasis, and triglyceride homeostasis, as well as fatty acid biosynthesis, fatty acid metabolism, and glycerolipid metabolism. Furthermore, ceRNA regulatory networks related to abdominal adipose development were constructed. The results of this study indicated that circRNAs can regulate lipid metabolism, adipocyte proliferation and differentiation, and cell junctions during abdominal adipose tissue development in chickens through complex ceRNA networks between circRNAs, miRNAs, genes, and pathways. The results of this study may help to expand the number of known circRNAs in abdominal adipose tissue and provide a valuable resource for further research on the function of circRNAs in chicken abdominal adipose tissue.

This study investigated fire resistance of strain-hardening cementitious composite (SHCC) incorporating Class C fly ash. The fly ash used is a local industrial byproduct. Adopting the local industrial byproduct would reduce the cost of SHCC significantly and reliance on overseas sources of fly ash. The results indicated that heat treatment up to 200 °C had negligible effect on strain capacity and strength of the SHCC specimens. Both compressive and tensile strengths began to deteriorate from 300 °C onwards. The SHCC specimens lost its strain-hardening feature at 300 °C and exhibited strain-softening behavior up to 600 °C. PVA fibers were found capable of increasing permeability of SHCC significantly before reaching melting point and reducing the risk of spalling under fire. This paper shows promising applications in introducing local industrial byproduct to produce green SHCC with excellent fire resistance.

This paper presents an experimental and analytical programme conducted on a total of seven reinforced concrete (RC) short beams, including one test at ambient temperature and six others at elevated temperatures. This study investigates experimentally the behaviour of RC short beams when subjected to elevated temperatures under the effect of shear-span-to-effective-depth (a/d) ratio and thermal-induced axial restraint. From the literature, this type of study on short beams has not been conducted before. It is experimentally shown that, for unrestrained short beams, as a/d increases, mid-span deflections at failure also increase and failure mode changes from diagonal splitting to shear tension. Besides, the influence of axial restraint on short beams is dependent on a/d ratio. For short beams of small a/d ratios (a/d ≤ 2.00), axial restraint increases mid-span deflections and flexural cracking, whereas it restrains deflections and shortens the failure duration of short beams with a/d ratio of 2.50. Furthermore, regardless of a/d, addition of axial restraint generally shifted the failure mode to a more brittle shear mode at elevated temperatures. Secondly, a simplified analytical model based on strut-and-tie-model (STM) is proposed and verified with test data to predict the performance of RC short beams at high temperatures. This model is applicable to both axially-restrained and unrestrained short beams subjected to elevated temperatures. The proposed STM is capable of providing consistently conservative and safe predictions of temperature profile, axial restraint force, load-carrying capacity and failure duration. Ministry of National Development (MND) National Research Foundation (NRF) The authors wish to acknowledge the first author’s scholarship and the funding for testing from the Singapore Ministry of National Development and National Research Foundation under L2 NIC Award No. L2NICCFP1-2013-4.

This paper introduces a preliminary numerical model used for simulation of reinforced concrete (RC) deep beams subjected to ambient and elevated temperature. A model for deep beams at ambient temperature condition is first proposed. Calibration of the model is achieved by comparing numerical predictions with test data collected from published literature. Subsequently, modifications to the model are adopted, including adjustments of material constitutive models, and considerations of thermal gradient and thermal restraint. Results from this study demonstrate that failure mode changes from shear to flexural-shear failure when temperature effect is considered. Strength reductions up to 67% are observed when the beam models are heated. Furthermore, diagonal concrete struts become wider in restrained beams compared to unrestrained beams. Improvement on beam strength and stiffness from unrestrained beams and change of failure mode to strut splitting are noted. The study also indicates that the strut-and-tie design approach in ACI 318 gives over-conservative predictions on shear strength of deep beams exposed to fire.