In-Plane Nonlinear Stability Analysis of Shallow Arches with Elastic Supports

Classical buckling theory has been researched extensively to determine the in-plane buckling behavior of parabolic, circular and catenary arches. To simplify the analyses, several assumptions are made. However, these simplified assumptions are not valid for shallow arches under significant vertical load which are characterized by their high geometric non-linearity. Prebuckling displacements should be accounted for for accurate in-plane buckling analysis of shallow arches. In reality, the supports of arches are not necessarily pin- or fixed-connections. An arch may be supported by elastic foundations or other structural elements that provide elastic restraint at the supports. In this work, elastic foundations are represented by horizontal and rotational springs. These support restraints may have a significant influence on the in-plane buckling behavior. In-plane non-linear stability analysis of shallow arches is performed in this thesis. Energy equations are derived by considering the total potential energy of the arch structure. The vanishing of first variation of total potential energy characterizes the equilibrium state, while the second variation of total potential energy falling to zero represents the transition from a stable state to an unstable state, from which the critical condition may be obtained. Finally, this thesis discusses the effects of horizontal and rotational restraints in calculation of in-plane buckling strength of shallow arches. Several examples are considered to illustrate the application of the theory, presented in this research for general practice

Influence of Irreparability Fragility on Seismic Vulnerability Assessment of Buildings

The probability that a building is sanctioned to demolition following an earthquake depends on several geotechnical, structural, strategic and financial decision variables. This paper explores the literature on post-earthquake reparability assessment of buildings focusing on structural characteristics and evaluates their approaches for four midrise code-compliant structural systems, namely, steel moment frame, reinforced concrete moment frame, light frame wood, and steel braced frame. The structural responses are estimated using incremental dynamics analysis (IDA) in accordance with FEMA P-695 provisions and the IDA results are relayed to a building-specific loss assessment framework to estimate their seismic vulnerability in terms of monetary losses. To estimate the impact of irreparability fragility, the loss assessment framework evaluates the vulnerability for each reference model at four levels of irreparability thresholds as well as for a case which excludes irreparability. The results show that the projected losses for these reference models are very sensitive to the assumptions for irreparability fragility. The impact of irreparability fragility on the final loss estimates, while varying by reference model, is relatively limited at lower levels of shaking intensity and tends to grow when incrementing toward higher levels of shaking. The paper also discusses a potential numerical issue with the framework to include irreparability in loss estimation, called ‘irreparability anomaly’, which arises from merely linking irreparability to peak residual drift. The observations emphasize the significance of the underlying assumptions for irreparability fragility in seismic vulnerability and loss assessment of building and call for further studies to establish more robust procedures

Seismic Vulnerability Assessment of Buildings Using a Statistical Method of Response Prediction

The seismic vulnerability functions for portfolio-level loss estimation are typically developed for general classes of buildings which may not be suitable to assess building-specific risks. Performance-based earthquake engineering (PBEE) provides the means to conduct building-specific seismic risk assessments. However, such assessments often rely on computationally-intensive analytical frameworks such as incremental dynamics analysis (IDA) which poses a challenge for many types of risk assessment projects. To expand its accessibility, FEMA P-58 outlines a simplified method to predict the nonlinear responses of buildings in which the scope is limited to lower levels of inter-story drifts (less than 4%). This limitation restricts its application to ductile structures, particularly when predicting the vulnerability of modern special moment frame systems. To overcome this shortcoming, this paper proposes an enhanced methodology by which the nonlinear responses of some common structural systems can be predicted by interpolating from a structural response database, itself developed by IDA. The database adopted in the current study consists of structural responses of 61 distinct modern buildings with variety of heights (number of stories), construction material, and lateral load resisting systems. Two building reference models, light-wood frame and special reinforced concrete moment frame with varying heights, are selected to validate the performance of the proposed statistical method. The predicted structural responses for these buildings are benchmarked against the corresponding IDA results. The estimated vulnerability of buildings based on the enhanced simplified method is in good agreement with IDA results. The proposed framework can be used in expedited seismic risk evaluations to estimate the losses of buildings in a large portfolio of diverse structures

Spatiotemporal transcriptomic atlas of mouse organogenesis using DNA nanoball-patterned arrays.

Spatially resolved transcriptomic technologies are promising tools to study complex biological processes such as mammalian embryogenesis. However, the imbalance between resolution, gene capture, and field of view of current methodologies precludes their systematic application to analyze relatively large and three-dimensional mid- and late-gestation embryos. Here, we combined DNA nanoball (DNB)-patterned arrays and in situ RNA capture to create spatial enhanced resolution omics-sequencing (Stereo-seq). We applied Stereo-seq to generate the mouse organogenesis spatiotemporal transcriptomic atlas (MOSTA), which maps with single-cell resolution and high sensitivity the kinetics and directionality of transcriptional variation during mouse organogenesis. We used this information to gain insight into the molecular basis of spatial cell heterogeneity and cell fate specification in developing tissues such as the dorsal midbrain. Our panoramic atlas will facilitate in-depth investigation of longstanding questions concerning normal and abnormal mammalian development.This work is part of the ‘‘SpatioTemporal Omics Consortium’’ (STOC) paper package. A list of STOC members is available at: http://sto-consortium.org. We would like to thank the MOTIC China Group, Rongqin Ke (Huaqiao University, Xiamen, China), Jiazuan Ni (Shenzhen University, Shenzhen, China), Wei Huang (Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China), and Jonathan S. Weissman (Whitehead Institute, Boston, USA) for their help. This work was supported by the grant of Top Ten Foundamental Research Institutes of Shenzhen, the Shenzhen Key Laboratory of Single-Cell Omics (ZDSYS20190902093613831), and the Guangdong Provincial Key Laboratory of Genome Read and Write (2017B030301011); Longqi Liu was supported by the National Natural Science Foundation of China (31900466) and Miguel A. Esteban’s laboratory at the Guangzhou Institutes of Biomedicine and Health by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA16030502), National Natural Science Foundation of China (92068106), and the Guangdong Basic and Applied Basic Research Foundation (2021B1515120075).S

Strength and Serviceability Performances of Southern Yellow Pine Cross-Laminated Timber (CLT) and CLT-Glulam Composite Beam

Cross-Laminated Timber (CLT) is a relatively new engineered mass timber construction material in the North America. While CLT was invented roughly three decades ago in Europe, it was not popular in the North America until recent years, in which there has been a surging demand for mass timber construction in the North American market. The advantages from the material itself and the level of pre-fabrication offers a flexible system suitable for large and tall wood buildings. However, the design provisions for CLT have not been developed for the building codes of the United States (US). Thus, the use of CLT is limited to custom projects. There were two phases in this research. During the inception of this research, there was no commercial production of structural grade CLT panels in the US using local wood species. The first phase of the research investigated the manufacturing process of CLT panels in a pilot scale using Southern Yellow Pine (SYP), a group of tree species native to the Southeast US. Tests were conducted to evaluate the adhesive and structural performances of CLT panels in flexural and shear. The test results showed that SYP can be used to produce CLT panels that meet and exceed the product standard requirements for CLT in the North America. The results generated from the pilot study were used in the second phase of the research to design, fabricate and test a full-scale 5 ft. wide and 40 ft. long CLT-Glulam composite floor system designed for long span applications. The proposed CLT-Glulam composite section is analogous to a typical precast concrete box girder, which is designed to improve the material efficiency. The CLT panels and Glulam beams in the composite floor system were fastened by screws installed at an incline angle. To investigate the feasibility of using the CLT-Glulam composite section for floor system in residential/office construction, a non-destructive vibration (modal) test was conducted to evaluate the serviceability behavior and destructive structural tests were performed to evaluate the flexure and shear strengths. The modal test utilized an instrumented heel-drop excitation to simulate the impact from human footsteps and accelerometers to record the vibration responses. The vibration test results revealed that the composite floor could produce vibration sensitive to building occupants. The results of the destructive tests verified that the composite floor system could safely carry the design load in terms of bending and shear strengths. Based on the findings of the experimental study, it was found that the design of the CLT-Glulam composite system is governed by serviceability and not ultimate strengths. It is recommended that, in addition to designing for the ultimate strengths, the serviceability criteria be considered with equal important as the strength design for improved occupant comfort

Detection of cervical high-grade squamous intraepithelial lesions and assessing diagnostic performance of colposcopy among women with oncogenic HPV

Abstract Background HPV screening tests may improve cervical cancer risk stratification and better guide decisions about follow-up with colposcopy/biopsy. This study aimed to estimate the risk of cervical intraepithelial neoplasia grade 2 or worse (CIN2+) among women with oncogenic HPV types and evaluate the performance of colposcopy in the diagnosis of histologic CIN2 + at Putuo Hospital, Shanghai, China. Methods This cross-sectional survey was conducted from February 2020 to December 2022 among women who were referred to colposcopy. Women with high-risk (HR) HPV-positive, cytology testing and colposcopy-directed biopsy were included. Results Univariate and multivariate analysis indicated that high-grade colposcopic impression ((OR, 17.61%, 95%CI: 11.54–26.85%) was associated with the highest risk for detecting CIN2+, followed by HSIL + cytology (OR, 6.90%, 95%CI: 3.56–13.37%) and HPV16/18 positive (OR, 2.91%, 95%CI: 2.12–3.99%). Overall, CIN2 + was detected in 14.6% of 2007 women. HPV16/18 had higher CIN2 + risks than other HR-HPV genotypes (30.1% vs. 10.2%, P 0.05). The diagnostic performance of colposcopy in diagnosis of CIN2 + by senior and junior colposcopists was comparable. Conclusions The results indicated that referral to colposcopy is recommended in managing women with HR-HPV positive, and colposcopic impressions provide key clues for identification CIN2+