Ahead of the Curve: Innovative Cold Bent & Insulated Glass Entry Wall

The owner of a 1970s, 24-story commercial office tower in Ottawa, Canada sought to rejuvenate their main lobby with a new glass entry wall.  The wall’s purpose is to provide a notable, grand entryway for the re-development of a commercial podium on a main thoroughfare.  The final design featured a 12 m tall by 35 m long curving glass fin wall.  The height of the wall is broken up into two sections. The first is a 9 m tall section between the ground floor and a third-floor terrace that provides the main building with a new front entrance, including a double-height space. The second is a cantilevered 3 m tall balustrade that creates a new third floor terrace.  The glass fins between the ground floor and third floor terrace are continuous, triple-laminated panels free of splices.  The curved panels have a 30 m curvature radius and feature a ceramic frit to prevent bird strikes and promote environmental sensitivity.  In addition, the panels are insulated glass units (IGUs) with a low-emissivity coating (low-e) to meet the City of Ottawa’s energy standards and the expected interior comfort of top tier retail and office space within the city.  Furthermore, the glass panels are supported at discrete points, so the team used a composite resin as the laminate for the interior and exterior lites to maintain the cold bent curvature radius. &nbsp

Prevention of Additional Building Settlement Due to Adjacent Construction at St. Francis Hospital and Medical Center in Hartford, CT

During excavation for the foundation of the new John T. O’Connell North Tower at St. Francis Hospital and Medical Center (SFHMC), in Hartford, Connecticut in 2008, Building 3, an immediately-adjacent five-story brick masonry building suddenly settled up to 1.5 in. and moved laterally about 5/8-in., resulting in severe cracking of interior and exterior bearing walls and floor slabs. The excavation was immediately backfilled within 30 feet of Building 3 and all construction activities were stopped until the condition of Building 3, which provided critical laboratory, pharmacy, and administrative support functions to the hospital, was evaluated and the cause of movement determined. SFHMC retained Simpson Gumpertz & Heger Inc. (SGH) to perform an investigation of the cause(s) of the building settlement and lateral movement, and to perform a condition assessment of the affected building. SGH determined that the building settlement was due to bearing failure of the Connecticut Valley Varved Clay (CVVC) stratum underlying the soil nailed excavation support wall installed below the perimeter soil bearing foundation of Building 3. In addition, it was concluded that Building 3 would not be able to sustain additional settlement, and alternate construction processes were needed to allow construction of the North Tower foundations to resume. SFHMC retained SGH to design the alternate construction processes needed. This paper presents the results of the forensic investigation and condition assessment of the distressed building as background for a detailed discussion of the alternate construction processes implemented to control further movement. This paper will present the design, monitoring, and construction considerations for new jacked pile underpinning of a portion of Building 3, a new cross lot braced soldier pile and lagging excavation support system adjacent to Building 3, and new micropiles to replace driven H piles specified for the North Tower foundation in the immediate vicinity of Building 3, all selected to minimize additional damage to the adjacent building. We will also discuss the challenges faced by Moretrench, the subcontractor engaged to implement the work, during construction of these systems and how these challenges were successfully overcome

Reusing Brick: Properties of Brick to Mortar Bond Strength

Brick and mortar is one of the most common wall systems used in the past several thousand years. These two components have evolved over the centuries as h as our scientific understanding of their performance. As brick and mortar wall science develops industry professionals need to reevaluate the design criteria, means and methods of construction and the performance expectations for these advanced wall systems. Building with used bricks was last critically evaluated over 80 years ago and based on the findings at that time; the industry has generally avoided rebuilding with used bricks. However, much has changed since then and this thesis revisits the topic of reusing bricks. This thesis addresses the performance of brick to mortar bond strength when reusing the same brick. This study aims to clarify the role of brick cleaning methods on flexural bond strength and to provide information that will improve the performance of brick to mortar building construction. Based on the results obtained, the following conclusions were made 1. New bricks had the highest initial rate of absorption (IRA), followed by reclaimed bricks cleaned via Stage 1, Stage 2 and Stage 3 procedures. 2. The flexural bond strength of brick to mortar increases as brick is cleaned more forcefully. Washing bricks with acid proved to be the most effective in increasing bond strength. 3. Flexural bond strength decreases as the average IRA of bricks increases. 4. Flexural bond strength of reclaimed brick is higher than that of new brick. Flexural bond strengths increased after mortar was applied for the second time

Concrete Deterioration and Diagnosis

Built primarily in the 1960’s, mid-century modernist concrete buildings are now at the age when we regard many as historic or architecturally significant (and thus as deserving of careful restoration and stewardship), but also at an age where many now exhibit significant deterioration. In this presentation, Matthew Bronski describes the most common maladies and deterioration mechanisms that can befall exposed concrete facades, outlines investigative and diagnostic approaches, and discuss the pros and cons of different rehabilitation treatment options, and the importance of tailoring the treatment to the malady

The old municipal chambers building: damaged but nor destroyed : will it be there in another 125 years?

The Old Municipal Chambers is a Category I heritage building situated in Worcester Street, Christchurch. It was designed by architect Samuel Hurst Seager in the Queen Anne Arts and Crafts Style and was opened in 1887. The two storey building is constructed in solid brick and incorporates several decorative features, and it is an important part of the cultural heritage fabric of Christchurch. Some securing works were undertaken in 1989 to improve its performance under seismic loads. This paper will outline damage during the earthquake on 4 September 2010, subsequent aftershocks and the 22 February 2011 earthquake which resulted in some localised zones of collapse. The structure of the building has been stabilised externally, to secure or allow retrieval of very significant heritage features. The high cost to repair the building makes the future of the building uncertain despite its very significant heritage value.In response to the building’s seismic vulnerability and possible retrofitting, finite element and simplified equivalent frame models were used for pushover analysis, enabling a complementary seismic evaluation from both approaches. The predictions identify the weak parts of the building and its expected failure modes, which are in agreement with the observed damage. The computations appear conservative, because the computed capacity curves provide insufficient capacity of the building to survive the recorded earthquakes. Given that there was uncertainty on the constitution of the floors, they were assumed as unidirectional by default, bidirectional diaphragm floors were also simulated in the simplified model, reflecting the securing works undertaken in 1990. In this case, a significantly better behaviour is observed. This paper will examine the seismic performance of the building, comparing results of analysis including both in-plane and out-of-plane behaviour, with actual damage. It will then consider conceptual scenarios for the future of the building, including comparison of performance and cost of both conventional and base isolation retrofit

Collections Sustainable Storage Initiative

The Worcester Art Museum is seeking a Planning Grant to develop its Collections Sustainable Storage Initiative (CSSI), an updated comprehensive Report and Master Plan of its collections storage spaces, environmental control and safety systems. A multi-disciplinary team is assembled to perform this work including consulting architects and engineers. As part of this effort the Museum will also implement the environmental data logging and analysis recommended by team consultant Image Permanence Institute (IPI). The planning goal is to develop ecologically sound, efficient, and sustainable guidelines supporting the Museum's collections storage spaces, storage furniture systems, environmental monitoring and control systems, as well as safety and protection systems. The CSSI Report will then form the basis for rethinking the existing connections between storage and permanent collections, and guide the way to more efficient and sustainable collections preservation

New Finite Element Models and Seismic Analyses of the Telescopes at WM Keck Observatory

On 15 October 2006 a large earthquake damaged both telescopes at Keck observatory resulting in weeks of observing downtime. A significant portion of the downtime was attributed to recovery efforts repairing damage to telescope bearing journals, radial pad support structures and encoder subsystems. Inadequate damping and strength in the seismic restraint design and the lack of break-away features on the azimuth radial pads are key design deficiencies. In May, 2011 a feasibility study was conducted to review several options to enhance the protection of the telescopes with the goal to minimize the time to bring the telescopes back into operation after a large seismic event. At that time it was determined that new finite element models of the telescope structures were required to better understand the telescope responses to design earthquakes required by local governing building codes and the USGS seismic data collected at the site on 15 October 2006. These models were verified by comparing the calculated natural frequencies from the models to the measured frequencies obtained from the servo identification study and comparing the time history responses of the telescopes to the October 2006 seismic data to the actual observed damages. The results of two finite element methods, response spectrum analysis and time history analysis, used to determine seismic demand forces and seismic response of each telescope to the design earthquakes were compared. These models can be used to evaluate alternate seismic restraint design options for both Keck telescopes

Development of seismic design methodologies for rigid wall-flexible diaphragm structures

Evidence indicates that the dynamic behavior of Rigid Wall – Flexible Diaphragm (RWFD) structures is dominated by the diaphragm’s response instead of the walls’ response, and this is a significant departure from the underlying assumptions of the widely used equivalent lateral force method in current building codes. RWFD buildings are common in North America and other parts of the world, and incorporate rigid in-plane concrete or masonry walls and flexible in-plane wood or steel roof diaphragms. With the use of a numerical computer modeling framework developed specifically for this type of building, this study sets out to investigate the seismic response of a variety of building archetypes with the intent to develop a simpler, more rational approach to the engineering design of RWFD buildings. A representative list of building archetypes is developed accounting for a variety of common parameters found in North America involving the building size, shape, diaphragm material, and diaphragm connections. Archetype designs are developed under ASCE/SEI 7-10 and this study’s proposed approach to develop design methodologies uses the FEMA P-695 methodology to evaluate building performance. In addition, two separate seismic force levels were utilized during the assessment representing both moderate and high seismic exposures to evaluate the impact of these parameters