Search

Structural irregularity in new buildings is sometimes desired for aesthetic reasons. Often it is unavoidable due to different uses in adjacent spaces within the building. The seismic behaviour of irregular structures is harder to predict than that of regular buildings. More comprehensive analysis techniques are often required to achieve adequate accuracy. Designing irregular structures poses additional challenges as the structural characteristics are unknown. There is a lack of practical design methods that reliably produce economic and seismically robust design solutions for highly irregular RC structures. This paper presents an extension of the Effective Modal Design (EMD) method from asymmetric-plan RC wall buildings to vertically setback asymmetric-plan RC wall buildings. EMD is a generalization of the Direct Displacement-Based Design method for highly irregular ductile uncoupled RC wall structures. EMD reverse engineers a multi-degree of freedom Equivalent Linear System to produce the most economic design solution that achieves the target performance levels. The utility of EMD is verified for a wide range of setback asymmetric-plan reinforced concrete wall structures using nonlinear time history analysis of reasonably realistic 3D structural models. Advantages of EMD include explicit consideration of nonlinear, torsional and ‘higher mode’ effects. The method produces capacity-designed design actions for all reinforced concrete walls in the seismic structural system. EMD only requires three response spectrum type analyses. It does not require time history analysis or pushover analysis. EMD is a practical seismic design method for generally irregular RC wall buildings that uses analysis techniques that most engineering practitioners are familiar and confident with. It was found that for over 95% of the structures considered, EMD achieved critical mean peak responses between − 20 and + 15% of the target response values, with a median of − 5%. This significant improvement in design accuracy and reliability (compared to traditional force based design) was achieved at the relatively small additional computational effort of two Response Spectrum Analyses. This demonstrates the value that the proposed Effective Modal Design method adds to the current spectrum of seismic design methods for irregular ductile RC wall structures.

This paper presents a new direct deformation based seismic design method called Effective Modal Design (EMD). The method is applied in this paper to multistorey two-way asymmetric-plan reinforced concrete wall structures. EMD is a generalization of the Direct Displacement Based Design method based on an inverse version (formulated herein) of the Effective Modal Superposition analysis method. The proposed EMD method should only be used when DDBD is not applicable. The accuracy and reliability of the proposed design method is verified for a wide range of asymmetric-plan reinforced concrete wall structures using nonlinear time history analysis of reasonably realistic 3D structural models. Advantages of EMD include explicit consideration of nonlinear, torsional and ‘higher mode’ effects. The method is direct without iteration and generates ‘capacity-designed’ design moments for all regions of all reinforced concrete walls in the seismic structural system. EMD only requires two response spectrum type analyses. It does not require time history analysis or pushover analysis. It is therefore relatively practical, and is intended for use in structural design offices for routine seismic design of multistorey asymmetric-plan RC wall buildings.

This chapter presents a methodology for designing irregular 3D RC frame buildings by minimizing the total steel volume while satisfying inter-story drifts and material strains limits. Indirectly, this process leads to reduction on the base shear and over-turning moments. The methodology relies only on analysis tools, without any need for knowledge or tools of structural optimization. Although iterative, the methodology requires only a few iterations for convergence. This makes the methodology very attractive for practical use.

This paper presents a new displacement based seismic design method called Practical Modal Pushover Design (PMPD). The method is applied to multistory one-way asymmetric-plan RC wall structures. PMPD combines concepts from Direct Displacement-Based Design with an inverse version (formulated herein) of Practical Modal Pushover Analysis (PMPA). PMPD generates designs which achieve peak deformations exactly equal to the governing deformation limits when analyzed with PMPA. An alternative method, Modal Pushover Design (MPD), which is, to some extent, an inverse version of Modal Pushover Analysis, is also discussed. MPD is computationally more demanding than PMPD, but has improved performance in cases where yielding may occur due to ‘higher mode’ response. Advantages of PMPD include explicit consideration of nonlinear, torsional and ‘higher mode’ effects. Iteration is limited to the response spectrum level, so multiple analyses of Multi-Degree of Freedom systems are not required. Capacity design principles are implemented directly from the start of the design process. A significant advantage of PMPD is that the engineer can have the same confidence in the structure’s seismic performance as he has in PMPA’s ability to predict the structure’s peak seismic responses. Therefore PMPD can be used for the seismic design of any structure for which PMPA is expected to provide acceptably accurate predictions of peak seismic responses. The effort required to carry out PMPD is similar to that required for PMPA. The only additional work consists of specifying a relative flexural strength distribution and executing a small number of iterations at the Single Degree of Freedom level.

A significant proportion of students entering international colleges in Thailand lack both the English language skills and critical thinking skills necessary for them to succeed in higher education. The ability to think critically has been correlated with successful reading comprehension and grade point average (GPA); however, many high schools in Thailand fail to develop this ability. This paper is part of an ongoing investigation into the use of Facione’s Holistic Critical Thinking Scoring Rubric to assess the critical thinking skills of students enrolled in an intensive English program for students entering a Thai university. Students’ critical thinking was assessed at the beginning and end of a 10-week term, during which students received explicit instruction on critical thinking. Some students evidenced measurable improvements over the term, and the rubric seems appropriate for future use. As critical thinking has been linked with academic success, this topic is relevant in diverse contexts.

This paper presents an analysis–redesign-type approach for the efficient seismic design of three-dimensional (3D) irregular RC frame structures for bidirectional ground motions. The designs...

This paper describes a pilot scale treatment plant that has been designed and built for the thermal inactivation in pig slurry of two viruses that infect pigs--African swine fever virus (ASFV) and swine vesicular disease virus (SVDV). The plant treats pig slurry continuously at a rate of up to 100 litres/hour and functions by heating the slurry, maintaining at least 99.99% of the slurry at the required temperature for a minimum period of 5 minutes, and then recovering the heat to raise the temperature of the incoming slurry. Results obtained indicated that SVDV was inactivated in pig slurry to below detectable levels with an alkaline pH (pH 7.5 to 8, as is usually the case) at a temperature of between 50 and 55 degrees C. In acidified slurry (pH 6.4), inactivation occurred between 55 and 60 degrees C. The difference in inactivation temperatures was probably due to the presence of free ammonia in the unacidified slurry. ASFV was inactivated by operating the plant at a temperature of 53 degrees C at a pH of 8.

African swine fever (ASF) and swine vesicular disease (SVD) are virus diseases that threaten the pig populations in Europe. This paper examines the effectiveness of two methods used to inactivate these two viruses in pig slurry, and then describes the design of a pilot plant which makes use of one inactivation method. The first method is the addition of alkali, specifically NaOH or Ca(OH)2 at various concentrations. ASF virus (ASFV) required 1% of either NaOH or Ca(OH)2 for inactivation; SVD virus (SVDV) required 1.5% NaOH or Ca(OH)2 for similar inactivation. The second method was the application of heat. ASFV was inactivated to below detectable levels at 56°C within 90 seconds, whereas SVDV required 60°C for inactivation within 90 seconds. Heat was identified as the most suitable method, and a pilot plant was designed and assembled for the inactivation of viruses in pig slurry at a rate of up to 100 litres per hour.