Evaluation and Retrofit of Masonry Building Envelope

Assignment 8

 Evaluation and Retrofit of Masonry Building Envelope

Multistory Structure Evaluation of Disque Hall

[pic 1][pic 2]

AE544

RIKKI MOORE

December 1st, 2015

Table of Contents

1.0 INTRODUCTION3

2.0 EVALUATION3

2.1 ARCHITECTURE3

2.2 STRUCTURAL4

2.3 ENVIRONMENTAL5

3.0 QUALITY ASSESSMENT6

4.0 REMEDIAL ACTIONS & CERTIFICATIONS6

1.  INTRODUCTION

The goal of this assignment is to look into a multistory building with brick veneer in our locality and evaluate the façade considering architectural, structural, and environmental considerations/requirements.  In addition, assess the quality of materials used to construct the building as well as the windows.  Furthermore, suggestions will be made for remedial actions to improve the structures overall performance, and finally, LEED certification criteria will be identified.  The building being evaluated is Disque Hall located at Market and JFK Boulevard on Drexel University’s campus.  

1.  EVALUATION

The following sections describe the many design considerations of a structure that must be considered in order to achieve a high performance, effective, and sustainable building envelope.  Through evaluating the components of Disque Hall’s architecture, structural design, and behaviors due to environmental factors, the overall performance of the façade can be determined.  

1.  ARCHITECTURE

When looking into architectural considerations for Disque Hall, it will be important to look at the building’s layout and shape, its overall efficiency, fenestration, detailing and movement joints.  The building’s footprint is roughly 165’ x 78’ with lecture halls attached at the back that are approximately 40’ x 140’.  It is a 9-story building with lobby and lecture hall space on the ground floor, basement space below, and 8 floors used for laboratory work.  When evaluating the building’s overall efficiency, for our purposes the 9-story section will be considered, i.e. the 165’ x 78’ x 108’ of the building assuming that floor to floor heights are approximately 12 ft.  Using the A/E ratio equation, for the footprint of Disque Hall, an approximate efficiency of 85% was calculated.  This directly relates the usable floor area (A) to the building envelope area (E) when comparing to a 100% efficient circle.  

In regards to fenestration, the total window area is miniscule (about 10%) as compared to the surface area of the building itself, thus limiting the amount of ambient light.  This, without a doubt, plays a major role in the overall thermal behavior of the spaces, and how much artificial lighting is needed within the building.  The windows consist of strings of small, geometric configurations that run top to bottom of central wall areas of the building.  Detail wise, the building is a small mix of three materials, concrete paneling, brick, and glass.  The two longer walls of the building contain the concrete panels while the smaller walls are strictly brick.  All walls utilize the window configuration as explained previously.  [pic 3]

Movement joints occur horizontally at each floor, which is visible on the outer brick veneer, while vertical joints occur between where the brick veneer meets the glass windows as well as where the glass meets the concrete panels.  These joints can be seen in the figure above.[pic 4]

1.  STRUCTURAL

Structurally it is important to consider how loads are determined and distributed through the building as well as calculating the internal forces of the envelope.  The basic structural systems at play within this building are steel columns, encased in concrete with cast-in-place concrete floor slabs.  It is suspected that based on the figures below, that the façade consists of hung panels, both brick and concrete.  These panels are hung from the floor slabs and then a CMU infill, backup wall allows the panels to be anchored to the structure along with shelf angles at the horizontal movement joints as seen in Figures 2 & 3 below.

[pic 5]

Figure 2: Original construction of the building with floor slabs and internal columns exposed.

[pic 6]

Figure 3: Typical Shelf Angle Detail which is the assumed method of hanging the brick veneer panels. (Source: International Masonry Institute)

These panels most likely are Non-Load Bearing (NLB) and carry all loads to the main structural system, which then transfer the loads through the floor slabs to the columns and down into the foundation of the building.  Internal force calculations must consider all applied building loads as well as wind loads.  With a basic understanding of envelope demand principles, it is understood that the windward wall (WWW) will experience the greatest internal forces as compared to the leeward wall (LWW) and the sidewalls (SW).  Furthermore, member resistance based on material properties, serviceability, and strength are also pertinent to gain a full understanding of internal calculations of the building envelope.  

Member resistance depends on material properties, overall geometry, and boundary conditions.  In addition, the material properties of Disque Hall are most approximately ones of large stiffness values which in turn enhance the serviceability and strength of the structure.  Although, there is a chance that based on the back up wall construction and its anchoring to the brick/concrete veneer that there is a larger chance for differential movement when outside forces are applied to the façade due to environmental factors which can cause brittle failure of the façade components through freeze-thaw, cracking, and water penetration.  To truly test serviceability of the building an in-depth analysis must occur.  The only way for this to truly be evaluated is if the actual construction methods of the building were known.  

1.  ENVIRONMENTAL

When considering the environmental impacts imposed on the building due to its location being in Philadelphia, in order to provide a valid evaluation of the façade, it is key to look into the thermal, moisture/air, sound, and fire properties of the building envelope.  The main objective of thermal design is to control heat flow, therefore with the veneer design as it is, assuming there is a rigid insulation of some thickness between the brick veneer and the CMU backup wall, the overall heat gains/losses of the building will be minimized.  The overall lack of fenestration will also help limit the amount of thermal energy lost throughout the day, therefore if the building is experiencing high traffic volume, it would not be surprising if occupants felt “warmer” than usual due to the buildup of thermal energy in the space.